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Summary

A simple, selective, precise, and reproducible high-performance thin-layer chromatography (HPTLC) method for the analysis of vicine in herbal extracts and formulations containing Momordica charantia was developed. The study was performed on aluminum-based pre-coated TLC plates (silica gel 60F254). The chromatograms of samples were developed in twin trough glass chamber pre-saturated with mobile phase comprised of ethyl acetate-methanol-water-formic acid (7.5:3:1:0.1, v/v/v/v) at room temperature (25 ± 2°C). The densitometric analysis was carried out in absorbance mode at 278 nm. The optimized mobile phase showed a compact spot of vicine (R F = 0.31 ± 0.02) from the other constituents present in the samples. The linear regression analysis data for the calibration plots showed good linearity (r 2 = 0.9990) with respect to peak area in the range of 200–1400 ng spot−1. The method was validated as per International Conference on Harmonization (ICH) guidelines. The limits of detection and quantification (50 and 150 ng spot−1, respectively) were also established. The proposed method has shown the excellent recovery (98.01–99.33%), which supports the suitability of the method for the analysis. Statistical analysis of the obtained data showed the selectivity of the proposed method for vicine estimation in the herbal samples.

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A high-performance liquid chromatographic (HPLC) method was developed for enantioresolution of amino alcohols using an indirect approach. Two sets of chiral derivatizing reagents (CDRs) having amino acids (CDRs 1–4; set A) and their amides (CDRs 5–8; set B) as chiral auxiliaries in cyanuric chloride (CC) moiety were synthesized and characterized. Diastereomers of eight amino alcohols were synthesized, under microwave irradiation, using each of the eight CDRs. The resulting diastereomers were separated by reversed-phase high-performance liquid chromatography (RP-HPLC) using C18 column and eluting mixtures of acetonitrile with aqueous trifluoroacetic acid (aq.TFA) in a linear gradient (45 min) with UV detection at 230 nm. The results (in terms of resolution Rs and retention factor k) obtained for the two sets of diastereomers were compared among themselves and among the two groups. The effects of chiral auxiliaries (in terms of acid and amides variants), constituting CDRs, on separation were also evaluated. The elution order for the diastereomers was determined. The separation method was validated for limit of detection (LOD), linearity, accuracy, precision, and recovery.

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Alcoholic-assisted dispersive liquid-liquid microextraction method (AADLLME) is used for the extraction, purification, and determination of bisphenol A in water samples by HPLC-UV. 1-octanol and methanol were selected as extraction and dispersive solvents of AA-DLLME procedure. The effects of several parameters of the AADLLME procedure (such as volume of extraction and dispersive solvents, amount of salt in sample solution, and extraction time) were investigated by a full factorial design. Then, the levels of significant factors were optimized using a central composite facecentered. The optimum conditions were obtained at 158 μL of extraction solvent, 500 μL of dispersive solvent, 1 min extraction time, and addition of 22% (w/v) of NaCl to the sample solution. Under optimum condition, the extraction recovery and the enrichment factor were determined, which were 91% and 65%, respectively. At these conditions, the limit of detection and the linearity were 0.10 and 1–100 μg L−1, respectively. The relative standard deviations for intra- and inter-day of extraction of bisphenol A (BPA) were 6.98% and 9.80%, respectively (for five measurements). Finally, the method was successfully applied for the determination of BPA in environmental water samples. In conclusion, it can be stated that the applied method is fast, simple, and environmentally friendly.

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Summary

The essential oil and the volatile compounds of Salvia aucheri Boiss. var. mesatlantica Maire were analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). The volatile compounds were detected using headspace-solid phase microextraction (HS-SPME) under optimized parameters. A comparative qualitative and quantitative study on the composition of the oils was carried out. For this, 38 compounds, constituting 95.40% of the oil, were identified in the essential oil by hydrodistillation (HD), and 32 compounds, representing 93% of the oil, were characterized by HS-SPME. The major components identified are camphor (49.80%, 51.80%), 1,8-cineole (9.50%, 9.40%), viridiflorol (8.80%, 1.40%), camphene (7.80%, 10.60%), α-pinene (2.90%, 4.50%), and p-cymene (1.50%, 2.40%) of essential oil and volatile compounds detected in HS-SPME, respectively. Quantitative but not qualitative differences have been found in the chemical composition of both analyzed samples depending on the extraction method. For these reasons, HS-SPME can be considered as an alternative technique for isolating volatiles from aromatic plants.

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Summary

A simple, sensitive, and precise high-performance liquid chromatographic (HPLC) method for quantitation of montelukast in human plasma has been developed and validated. Commercially available candesartan cilexetil was used as an internal standard. After protein precipitation, montelukast and candesartan cilexetil (I.S.) in human plasma were analyzed using mobile phase containing 62% v/v acetonitrile and 38% v/v buffer (containing 1 mL L−1 triethylamine as peak modifier, final pH adjusted to 2.5 with orthophosphoric acid). Chromatographic separation was achieved on a BDS Hypersil-C18 column (50 × 4.6 mm i.d., particle size 5 μm; Thermo Electron Corporation, USA) using isocratic elution at a flow rate of 1.5 mL min−1. The signals were monitored using a fluorescence detector set at 350 nm for excitation and 400 nm for emission. The total time for a chromatographic separation was ∼3 min. The validated quantitation ranges of this method were 5–300 ng mL−1 with coefficients of variation between 1.75% and 9.38%. Mean recoveries were 91.8 ± 3.8%. The within- and between-batch precisions were 0.74–2.46% and 1.64–7.87%, respectively. The within- and between-batch relative errors (bias) were 0.14–3.3% and 0.08–4.6%, respectively. Stability of montelukast in plasma was >94.7%, with no evidence of degradation during sample processing and 30 days storage in a deep freezer at −70°C. This validated method is sensitive and simple with between-batch precision of <8% and successfully applied for the bioequivalence studies. The formulations were compared using the following pharmacokinetic parameters: AUC0−t, AUC0−∞, and C max. No statistically significant difference (p > 0.05) was observed between the logarithmically transformed AUC0−t, AUC0−, and C max values.

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A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of glycyrrhizin, formononetin, glycyrrhetinic acid, liquiritin, isoliquiritigenin, and licochalcone A in licorice. An Eclipse Plus C18 column (I.D. 4.6 × 100 mm, 3.5 μm particle size; Agilent) was used in the analysis. Electrospray ionization (ESI)-tandem interface in the negative mode was performed, and multiple reaction monitoring (MRM) was employed with the precursor multiple reaction monitoring production combination for the determination of six analytes. The average recoveries ranged from 98.30% to 100.13% with relative standard deviations (RSDs) ≤ 1.95%, and limits of detection (LODs) ranged from 2.1 to 3.6 pg. The applicability of this analytical approach was confirmed by the successful analysis of six samples. The results indicated that the established method was validated, sensitive, and reliable for the determination of six analytes in licorice.

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Authors: M. Zhu, J. A. Duan, Y. P. Tang, J. M. Guo, E. X. Shang and Z. H. Zhu

Summary

An efficient and robust method for analyzing constituents of a well-known traditional Chinese medicine (TCM) formula SiWu decoction (SWD) contains Angelicae Sinensis Radix (ASR), Chuanxiong Rhizoma (CR), Paeoniae Radix Alba (PRA), and Rehmanniae Radix Praeparata (RRP) by ultra high-performance liquid chromatography (UHPLC)/time-of-flight mass spectrometry (TOF-MS) was established. The method efficiently applied to the separation of 75 compounds, including organic acids, phthalides, phenylpropanoid glycosides, iridoid glycosides, monoterpene glycosides, and galloyl glycosides in the complex prescription, 52 compounds in this study can be unambiguously identified or tentatively characterized. The separation was achieved within 20 min at the optimized chromatographic conditions. Our study provided a reliable and high-efficient method for the understanding of the chemical basis of SWD.

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Galantamine hydrobromide was subjected to oxidative stress degradation using hydrogen peroxide and analyzed as per the chromatographic conditions described in European Pharmacopoeia. The drug showed considerable degradation at ambient temperature resulting in the formation of two degradation products at relative retention times (RRTs) 0.63 and 2.52. The minor degradant at RRT 0.63 was identified as galantamine N-oxide. The principal degradant formed at RRT 2.52 was found to be unknown and has not been reported previously. The unknown impurity was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by isolation using semi-preparative high-performance liquid chromatography (HPLC). The isolated impurity was characterized using one-dimensional, two-dimensional nuclear magnetic resonance spectroscopy (1D and 2D NMR) and elemental analysis (EA). The principal degradant was found to be formed due to the generation of bromine and subsequent attack on the aromatic ring via in situ reaction between hydrogen bromide and hydrogen peroxide. The unknown impurity was characterized as (4aS,6R,8aS)-5,6,9,10,11,12-hexahydro-1-bromo-3-methoxy-11-methyl-4aH-[1]benzofuro [3a,3,2-ef] [2] benzazepin-6-ol.

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Chestnut exhibits anti-inflammatory, styptic, anti-diarrhea, and analgestic effects as a traditional Chinese medicine. There is increasing evidence that shows that the consumption of chestnuts has become more important in human nutrition due to the health benefits provided by the antioxidants. The phenolic compounds are responsible for major bioactivities, such as anti-tumor and anti-oxidation. A high-performance liquid chromatography (HPLC) method with diode array detection (DAD) was established for the simultaneous determination of six phenolic compounds (gallic acid, GA; protocatechuic acid, PR; catechin, CA; epicatechin, EP; quercetin, QU; kaempferol, KA) in Chinese chestnut (Castanea mollissima blume) kernel. The sample followed by separation on Eclipse XDB-C18 column (150 × 4.6 mm, id., 5 μm) with gradient elution of methanol-1.0% acetate acid solution as a mobile phase, at a temperature of 30°C, under the ratio of 1.2 mL min−1, with 5 μL injection volume, and multi-wavelength synthesis was used with DAD. The correlation coefficients were larger than 0.999, the recoveries were 97.58% for GA, 100.41% for PA, 96.23% for CA, 101.38% for QU, 99.15% for EP, and 98.60% for KA, relative standard deviation (RSD) were 1.04% for GA, 1.21% for PA, 1.09% for CA, 1.19% for QU, 1.06% for EP, and 1.20% for KA. This method was applied for the determination of phenolics in chestnut kernel and was found to be fast, sensitive, and suitable.

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Authors: Aiichiro Nagaki, Kana Akahori, Yusuke Takahashi and Jun-ichi Yoshida

Living anionic polymerization of perfluoroalkyl methacrylates initiated by 1,1-diphenylhexyllithium was conducted without adding lithium chloride in an integrated flow microreactor system. The high degree of polydispersity index (PID) control was achieved at 0 °C (2-(nonafluorobutyl)ethyl and 2-(tridecafluorohexyl)ethyl methacrylates) or −40 °C (2,2,2-trifluoroethyl methacrylate). The subsequent reaction of a reactive polymer chain end with alkyl methacrylates or tert-butyl acrylate led to the formation of fluorine-containing block copolymers with narrow PDI.

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A facile and reproducible method based on microreaction technology has been developed for the continuous preparation of layered double hydroxides (LDHs) with narrow particle size distribution. Mg–Al–CO3, Mg–Al–NO3, Mg–Al–Cl, and other different kinds of LDHs containing binary, ternary, and quadruple metal cations were successfully prepared. Due to the enhanced mixing, a high slurry throughput of 300 mL/min in a single reaction channel was obtained.

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Plain and N-doped carbonaceous particles are synthesized from biomass resources such as glucose via continuous hydrothermal carbonization (HTC) process at 200 °C and 250 psi for the first time using a microfluidic system in a fast and continuous manner. The continuous HTC is controlled by reaction time (3.7–30 min) and concentration (0–10 wt.%) of ethylenediamine as a nitrogen additive to produce a series of the plain carbonaceous and N-doped carbonaceous particles with size range from 0.8 to 1.2 um. The as-synthesized and the pyrolyzed particles are characterized by various analytical instruments to understand their chemical structures with elemental compositions, morphology of particles, and thermal defunctionalization.

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The present paper describes various application possibilities of high-performance thin-layer chromatography (HPTLC) for qualitative and quantitative toxicological-chemical analysis. Exemplified by 115 toxicological relevant drugs, a simple and fast two-dimensional HPTLC procedure is presented, suited for the undirected qualitative toxicological-chemical analysis. Here, we demonstrate that the separation performance can be increased significantly by identifying substances on the basis of the two migration distances together with the remission spectra maxima, measured with a HPTLC scanner (densitometer). The values calculated for the discrimination power and the identification power were found to be comparable with those of other chromatographic procedures, commonly used for toxicological-chemical analysis (high-performance liquid chromatography [HPLC], gas chromatography-mass spectrometry [GC-MS], and liquid chromatography-mass spectrometry [LC-MS]). While a scanner increases clearly the efficiency of qualitative analysis, it is indispensable for quantitative analysis. The broad applicability of the HPTLC-densitometry for the directed quantitative toxicological-chemical analysis has been shown by the description of methods for 144 drugs. Particularly, it has to be emphasized that the suitability of the two-dimensional HPTLC has been demonstrated also for quantifications with internal standard for a large number of determinations of relevant drugs, leading to a significant increase in efficiency. For sample preparation of biological material, seven methods have been used for the tested drugs. With a total of ten mobile phases (solvent mixtures), it has become possible to determine all 144 substances by HPTLC. The advantages of HPTLC (low price, high variability), but also its indisputable disadvantages in its application in the toxicological-chemical analysis are discussed. HPTLC in the presented form is suitable for both qualitative and quantitative analysis and may well be of benefit to resolve specific problems, even in the presence of more sophisticated analytical methods in a toxicological laboratory.

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Two methods were described for the simultaneous determination of ciprofloxacin HCl (CIP) and moxifloxacin HCl (MOX) in their binary mixture present in industrial wastewater. A solid-phase extraction procedure (SPE) based on retention on HLB OASIS cartridges and elution with a mixture of methanol-water in acidic medium was preformed, and then both fluoroquinolones were separated using two chromatographic methods. The first method was based on high-performance liquid chromatographic separation of the two drugs on reversed-phase Zorbax C18 column. The mobile phase consisted of monobasic potassium phosphate (50 mM, pH 2.5, adjusted with phosphoric acid) and acetonitrile (80:20, v/v). Flow rate was 1 mL min−1. Quantitation was achieved with ultraviolet (UV) detection at 278 nm. Linearity was found to be over the concentration range of 1–50 μg mL−1 for both CIP and MOX. The second method was based on the thin-layer chromatographic (TLC) separation of the two drugs followed by densitometric measurements of their bands at 278 nm. The separation was carried out on silica gel 60 F254 plates, using methanol, ammonia, and methylene chloride (55:35:20, v/v) as a developing system. The linearity was found to be in the range of 0.25–2.5 μg band−1 for both CIP and MOX. Both methods were optimized and validated as per International Conference on Harmonization (ICH) guidelines. Separation was developed on spiked water samples and checked on process wastewaters of industrial origin after SPE sample pretreatment.

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Authors: Djavanshir Djozan, Ghader Karimian, Abolghasem Jouyban, Fahime Iranmanesh, Hooshangh Gorbanpour and Ali Alizadeh-Nabil

This paper presents a new method based on thin-layer chromatographic separation, and image analysis (TLC-IA) of saffron colorant compounds for the discrimination of saffron from different origins. The color compounds of dried and ground saffron stigmas are extracted and separated by thin-layer chromatography at optimum conditions. After chromatographic development, the chromatograms are photographed, and intensity profiles of RGB characteristics are produced and processed by specially designed image analysis software. The main factors such as the extraction procedure of color compounds, chromatographic system (stationary and mobile phase), and designing of image analysis software are described. This method includes a new and fast data acquisition and does not require expensive instruments. The method also allows for comparison of different types of saffron using R F values, color range, and intensity of the separated color components. This method is successfully applied to determine the saffron from different regions of Iran and various adulteration colorants.

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Author: Bernd Spangenberg
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There is a large chemical variability between commercially available Echinacea for both research and consumption impacts on the quality and efficacy of these products. Globally, herbal industries are largely unregulated, leaving manufacturers responsible for quality control. Several recent efforts to improve regulation have created a need for rapid, accurate, and reliable assays suitable for a quality control setting. Thus, the aim of this study was to develop and validate a high-performance thin-layer chromatographic (HPTLC) method for the quantitative analysis of commercial Echinacea products. HPTLC and high-resolution plate imaging were used to separate and quantify the amounts of three phenylpropanoid compounds which were used then as markers in product quality assessment. The developed method was validated according to the current International Conference on Harmonization (ICH) guidelines in terms of accuracy, precision, linearity, specificity, limits of quantification and detection, and robustness and was used to quantify these markers in three commercial Echinacea formulations. The method achieved better limits of detection than previous assays, despite exhibiting lower repeatability, particularly when quantifying cichoric acid. This work has demonstrated that high-resolution plate imaging can be used as a reliable method for the quantitative analysis of commercial Echinacea products.

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In view of high pharmacological significance and urgent need to identify high-yielding plant sources of betulin (1) and betulinic acid (2), quantitative high-performance thin-layer chromatographic (HPTLC) analysis has been done on various parts of Diospyros sylvatica. For separation of both compounds, HPTLC silica gel 60 F254 plates were used with chloroform-methanol-formic acid (98:2:2) as the mobile phase. The method was validated for selectivity, sensitivity, accuracy and precision. While betulin was found in maximum amount in stems (0.08%), betulinic acid accumulates maximally in roots (0.29%). The developed HPTLC method is simple, rapid, and highly suitable for the quantification of betulin and betulinic acid in various related species and genera.

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A high-performance thin-layer chromatography (HPTLC) method for the analysis of seven fructooligosaccharides (FOS, DP3-9) in Morinda officinalis How. (M. officinalis) and Arctium lappa Linn. (A. lappa) has been established. The chromatographic analysis was developed twice with a mobile phase consisting of n-butanol-isopropanol-water-acetic acid in volume composition 7:5:2:1 and obtained on silica gel 60 plate. The chromatograms were visualized with 1-naphthol-sulfuric acid reagent. Densitometric detection was performed in visible light at 585 nm for seven FOS. The analytical range was set as 131–1050 ng for FOS. Calibration was linear within the selected range (R 2 > 0.9901). The developed method was applied for the simultaneous determination of seven FOS in M. officinalis and A. lappa. The results indicated that the contents of FOS are variant in different M. officinalis samples, but constant in different A. lappa samples. This HPTLC method was found to be simple, stable, and reproducible. Hence, the developed HPTLC method would be an important tool for the quality control of FOS in medicinal plants.

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Authors: Satyabrata Mohapatra, Nishant Manglani, Dilmel Krishnan, Ilavarasu Arumugam, Madhavan Vijayakumar and Uddagiri Babu

Arnebia nobilis has gained an increasing popularity for the recently recognized various pharmacological activities. The root part of A. nobilis is a useful source for the naphthoquinones. For their identification and quantification, a high-performance thin-layer chromatographic (HPTLC) method was established. Chromatography was performed on silica gel HPTLC aluminum plates with toluene-ethyl acetate-formic acid (80:19:01, v/v) as mobile phase leading to sufficient separation of the components. HPTLC analysis proved to be an inexpensive method for the quantification of arnebin-1.

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A simple, sensitive, and precise high-performance thin-layer chromatographic method has been developed for the estimation of torsemide and amiloride hydrochloride in the pharmaceutical dosage form. Thin-layer chromatographic (TLC) aluminum plates precoated with silica gel 60 F254 were used as the stationary phase, while chloroform-methanol-ammonia (7.5: 3.5: 1, v/v) as mobile phase was used. The R F values observed were 0.46 ± 0.01 and 0.24 ± 0.01 for torsemide and amiloride hydrochloride, respectively. The densitometric analysis was carried out in absorbance mode at 286 nm. The method was linear in the range of 100–600 ng spot−1 for torsemide and 50–300 ng spot−1 for amiloride hydrochloride. The method was validated as per the International Conference on Harmonization (ICH) guidelines. The limit of detection and limit of quantitation were found to be 19.94 ng spot−1 and 100 ng spot−1, respectively, for torsemide. The limit of detection and limit of quantitation were found to be 12.86 ng spot−1 and 50 ng spot−1, respectively, for amiloride. The proposed method was successfully applied to the estimation of torsemide and amiloride hydrochloride in the pharmaceutical dosage form.

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Standardization has become mandatory for global acceptance of herbal oriental medicines which lack validated methods of analysis due to their complex nature. Thus, a simple and fast method was developed for the simultaneous quantitative determination of three biologically active flavonoid compounds, i.e., kaempferol, rutin, and quercetin in extracts and marketed formulations containing Phyllanthus niruri (Bhuiamla) and Emblica officinalis (Amla). The separation was performed on thin-layer chromatography (TLC) aluminum plates precoated with silica gel 60 F254. Good separation was achieved in the mobile phase composed of chloroform-methanol-formic acid and detected at wavelength 254 nm in reflectance-absorbance mode. The developed method was well validated by different parameters mentioned in International Conference on Harmonization (ICH) guidelines such as linearity, accuracy, precision, etc. The linear regression data for the calibration plots showed a good linear relationship with r = 0.9997, 0.9998, and 0.9998 for kaempferol, rutin, and quercetin, respectively. The validated method was successfully applied to determine the contents of three biomarkers in a single run in Bhuiamla Vati and capsule (Ayurvedic and modern solid dosage form, respectively) and Amla Vati and Amla tincture (homeopathic preparation). The present high-performance thin-layer chromatographic (HPTLC) method, which was used for the standardization of various marketed traditional medicines of two different medicinal plants, is being reported the first time with these three biomarkers.

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Phyllanthus amarus, a well-known drug of the Indian Systems of Medicine, possesses a wide variety of pharmacological activities including anticancer, anti-inflammatory, hepatoprotective, immunomodulatory, nephroprotective, and radioprotective activity. The pharmacological activity of P. amarus is due to the presence of various lignans and flavonols, the major ones being phyllanthin, hypophyllanthin, and niranthin. A simple high-performance thin-layer chromatographic method has been developed for the simultaneous quantification of these three lignans from the whole plant of P. amarus. The optimized mobile phase n-hexane-ethyl acetate-glacial acetic acid (9:3:0.3, v/v) gave good separation of phyllanthin, hypophyllanthin, and niranthin on thin-layer chromatography (TLC) silica gel 60 F254 layers when quantified at 230 nm. The developed method was validated according to the International Conference on Harmonization (ICH) guidelines for precision, repeatability, accuracy, and linearity. Peak identity and purity were determined. This is the first report of simultaneous quantification of phyllanthin, hypophyllanthin, and niranthin from P. amarus using normal phase TLC silica gel 60 F254 plates. The developed method is simple, precise, accurate, cost-effective, and less time-consuming.

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Authors: Żaneta Rembisz, Robert Zakrzewski, Witold Ciesielski, Monika Skowron and Ramón Martínez-Máñez

A highly specific and sensitive chromatographic method for the determination of sulfide ions was developed. The procedure is based on the sensitive and specific reaction of sulfide ions with 4-[p-(N,N-dimethylamino)phenyl]-2,6-diphenylpyrylium cations. The product of the reaction is a thiopyrylium derivative which can be quantitatively determined. Separations were performed on cellulose thin-layer chromatography (TLC) plates with a mixture of phosphoric buffer (pH 3.0), propan-2-ol, and acetonitrile (4:4:0.5, v/v) as the mobile phase. The thiopyrylium derivative was visible in the form of blue spots against a colorless background, which were converted into a chromatogram using TLSee software. Linearity was obtained in the range of 40–500 pmol per spot. The limits of detection and quantification were 10 pmol per spot and 33 pmol per spot, respectively. The proposed method was successfully used for the detection and determination of sulfide ions in water samples from the Busko Zdrój health resort.

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Authors: Anshu Kumar, Jafar Hasan, Ashok Majji, Appasaheb Avhale, Sreelekha Gopinathan, Pritesh Sharma, Dattatray Tarange, Rishab Bajpai and Anil Kumar

Regioregular poly(3-hexylthiophene), rr-P3HT, has been commonly synthesized using Grignard metathesis (GRIM) polymerization and is used as an active material for large area printing of various optoelectronic devices. Batch to batch reproducibility which is very crucial for the development of a large area printing technology for any material still remains one of the major challenges for bulk synthesis. This is due to the insolubility of the GRIM catalyst (1,3-bis(diphenylphosphino)propane nickel(II) chloride) in polymerization solvents. In this article, we have successfully developed a continuous-flow process for the ultrafast syntheses of rr-P3HT with high throughput and low polydispersity index (PDI). The key to success was the use of 3,4-ethylenedioxythiophene, EDOT, as an inert solvent for dissolving the GRIM catalyst. We could successfully carry out the flow syntheses of rr-P3HT at high concentration (500 mM monomer solution) with low PDI (~1.2) along with good batch to batch reproducibility and high throughput of 32.8 g per channel per hour for rr-P3HT. The combination of higher monomer concentration with ultrafast polymerization resulted in an efficient process for the large-scale syntheses of rr-P3HT with reduced chemical waste. Furthermore, the optical studies along with electrical characterization indicated better packing and higher charge carrier mobility as compared to the commercial samples with high polydispersity index.

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In this study, two practical and scalable procedures were developed for the synthesis of N-arylacetyl oxazolidinone, which is an intermediate for the preparation of N-allyloxylcarbonyl 3,5-dihydroxyphenylglycine. The key sequence in the developed procedures was a photochemical Wolff rearrangement–nucleophilic addition in a micro-flow reactor. A power-saving, inexpensive, and readily available light source (4-W portable ultraviolet [UV] lamp) along with a fluorinated ethylene propylene copolymer (FEP) tube was employed in the developed procedures. The first-generation procedure afforded the desired N-arylacetyl oxazolidinone in the highest yield. The yield was lower in the second-generation procedure, but it afforded pure N-arylacetyl oxazolidinone without column chromatographic purification. The use of the two parallel channel tube reactors enabled the gram-scale preparation of N-arylacetyl oxazolidinone. N-Allyloxylcarbonyl 3,5-dihydroxyphenylglycine was successfully prepared via the second-generation procedure.

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Authors: László Pásztor, E. Dobos, G. Szatmári, A. Laborczi, K. Takács, Zs. Bakacsi and J. Szabó

The main objective of the DOSoReMI.hu (Digital, Optimized, Soil Related Maps and Information in Hungary) project is to significantly extend the potential, how demands on spatial soil related information could be satisfied in Hungary. Although a great amount of soil information is available due to former mappings and surveys, there are more and more frequently emerging discrepancies between the available and the expected data. The gaps are planned to be filled with optimized digital soil mapping (DSM) products heavily based on legacy soil data, which still represent a valuable treasure of soil information at the present time. The paper presents three approaches for the application of Hungarian legacy soil data in object oriented digital soil mapping.

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The present state of our landscapes is not only the result of various natural processes, but of the anthropogenic effect that humankind had since its occurrence within the landscape. These processes reach back as far as the beginning of the known archaeological eras. One of the major problems in the reconstruction of landscape evolution is bridging the gap between the archaeologically well-defined periods and the extensively documented last three centuries. Remains of the various archaeological periods are conserved in the soil and form part of the soil’s memory function; but soils develop and might get destroyed over time. However, soils also bridge the heritage of once lived cultures with those events of the last few centuries that are reconstructable, based on written and map sources. It must be noted that the possibility of human-induced soil destruction is significantly higher within the mentioned centuries, therefore the understanding of land-use changes, land-use trajectories are essential in assessing the possible degradation of soils, archaeological sites and heritage.The present contribution attempts to integrate the tools of geoarchaeology, soil science and landscape ecology with the archaeological knowledge of the Cikola valley (Mezőföld, Hungary). The historic land-use changes within the target area of the valley were detected and quantified with the trajectory tracking method. This was compared to soil conditions, geoarchaeological data and to information collected through on-site archaeological field walking. The comparisons of archaeological sites that have been less or more intensively used in the past, differ both in soil conditions, and in the condition of the archaeological phenomena they preserve. The trajectory values gave a good estimate on the possible and predictable disturbance of the archaeological phenomena preserved at the examined sites.

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Results of the performed preliminary particle size determination (PSD) experiments of soils show the importance of the preparation details of the laser diffractometer method (LDM). The analysis of the effect of each preparation factor on soil PSD data calls attention to the need for working out standard instructions defining the pre-treatments and settings for the LDM instrument. Further laboratory experiments involving larger soil datasets are required for the better understanding of the effects of soil pre-treatments and settings on PSD data. There is a practical reason of substituting the time-consuming pipette method with the LDM. In case of this substitution, linkages of the LDM PSD data and other soil properties are to be established. Correlation study of the LDM and conventional PSD data could make the harmonization of newly built and historical databases possible. Finally, the introduction of the LDM technique to soil physical methodology could generate the reevaluation of existing soil physical interrelations.

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In a long-term fertilization field experiment set up in Debrecen-Látókép in 1983 on calcareous chernozem soil the changes in the chemical and microbiological characteristics related to the carbon and nitrogen cycles of the soil are shown and evaluated. The soil samples were taken in the 26th and 27th years of the experiment, (in 2009, 2010) from maize monoculture and tri-culture. In addition to the effects of fertilizer doses, correlations among soil chemical and microbiological properties were established; and the various ratios among some microbiological parameters were also evaluated.The elements of NPK fertilizers increased together with the doses, so the elements’ effect cannot be separated, the minimum factor is not identifiable.With increasing fertilizer doses, the soil pH decreased in both the mono- and triculture, parallelly there was a significant increase in hydrolytic acidity. A close negative correlation was proved between the pH(H2O) and hydrolytic acidity and pH(KCl) and hydrolytic acidity. An increased soil nutrient content was recorded in each NPK treatment, the available phosphorus and nitrate content increased in a higher proportion than that of potassium.Among the measured parameters of the carbon and nitrogen cycles fertilization had a positive influence on the organic carbon (OC), organic nitrogen (ON), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) contents, the number of cellulose decomposing and nitrifying bacteria, the nitrate exploration and CO2-production, while it mainly had negative effects on the investigated enzymes (saccharase and urease) activity.Evaluating the ratios among the measured parameters, fertilization seems to have promoted the increase in nitrogen-containing organic compounds, because the OC/ON and MBC/MBN ratios decreased due to the effect of different doses of NPK fertilizers in both cultures.

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In water quality research the interest in online biofilm monitoring techniques has recently increased significantly. Christiani et al. (2008) presented a simple electrochemical technique to monitor electro-active biofilm in soil, based on the cathodic polarisation of stainless steel electrodes. Authors present an improved method, in which stainless steel was replaced by copper. By using copper-zinc electrodes authors have shown difference in the electrical potential between sterilized and native soils even at low moisture content.

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The effects of genotypes, nutrient and water supply on the dry matter production and potassium uptake dynamics of maize (Zea mays L.) were studied on chernozem soil in the Debrecen-Látókép long-term field experiment (Eastern Hungary).According to the experimental results and calculations it can be concluded that — in addition to the previously used and considered soil and plant nutrient contents — the calculation of the plant-extracted nutrient amount (depending on the applied hybrid, NPK nutrient levels and water supply) is suggested to enable the characterization of the growth and nutrient demand dynamics of maize genotypes. This parameter gives information not only about the available nutrient amount at a given sampling time, but about the supply level of plants up to the sampling time as well. For the proper characterization of the mentioned dynamics of maize plants authors suggest to take the following sampling times into consideration: the intensive vegetative growth period, the switch between the vegetative and generative growth phases (silking), and the grain filling phase.

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Winter wheat (Triticum aestivum L.) yield samples taken from a consecutive series of crop years representing drought, normal and moist conditions at the Nagygombos experimental site of the Szent István University have been evaluated. The impact of N topdressing and crop year conditions on the performance of protein and wet gluten content were studied.The results suggest that ascending levels of N topdressing, and increased number of applications had a beneficial effect on the protein content, as well as on wet gluten values. Crop year had a significant effect on quality manifestation. The drier the crop year, the better the recorded quality performance. The magnitude of changes was bigger in case of gluten than in that of protein values. There were minor differences between the two varieties examined, especially in their response patterns to nitrogen supply. Dough formation depends mainly on the gliadin/ glutenin ratio, but there is less information on the agronomic and climatic impacts that may cause alterations in that.

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The Sopron Wine Region is one of the most significant and historical wineproducing regions in Hungary, with a total area of 4300 hectares, out of which 1800 hectares are used for grapevine cultivation. The aim of the present research was to carry out basic measurements for soil, grape and wine in the Sopron Wine Region to obtain preliminary results for future investigations.The demonstrated methods are suitable for the combined analysis of soils, grape berry and wine. It was established that there are differences between the composition of grape berry and wine of the selfsame vine cultivar in the investigated areas. The terroir effects of the Sopron Wine Region have not been studied as yet extensively, although there are several international studies in this field (e.g. Hugget, 2006; Csikász-Krizsics & Diófási, 2008; Fernández-Marín et al., 2013). By future measurements carried out on a large number of samples and with sophisticated multivariate statistical analysis the relationships between measured physical and chemical parameters can be evaluated in the region, providing basis for establishing terroir aspects.

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Authors: Éva Lehoczky, M. Kamuti, N. Mazsu, J. Tamás, D. Sáringer-Kenyeres and G. Gólya

Plant nutrition is one of the most important intensification factors of crop production. The utilization of nutrients, however, may be modified by a number of production factors, including weed presence. Thus, the knowledge of occurring weed species, their abundance, nutrient and water uptake is extremely important to establish an appropriate basis for the evaluation of their risks or negative effects on crops. That is why investigations were carried out in a long-term fertilization experiment on the influence of different nutrient supplies (Ø, PK, NK, NPK) on weed flora in maize field.The weed surveys recorded similar diversity on the experimental area: the species of A. artemisiifolia, S. halepense and D. stramonium were dominant, but C. album and C. hybridum were also common. These species and H. annuus were the most abundant weeds.Based on the totalized and average data of all treatments, density followed the same tendency in the experimental years. It was the highest in the PK treated and untreated plots, and significantly exceeded the values of NK fertilized areas. Presumably the better N availability promoted the development of nitrophilic weeds, while the mortality of other small species increased.Winter wheat and maize forecrops had no visible influence on the diversity and the intensity of weediness. On the contrary, there were consistent differences in the density of certain weed species in accordance to the applied nutrients. A. artemisiifolia was present in the largest number in the untreated control and PK fertilized plots. The density of S. halepense and H. annuus was also significantly higher in the control areas. The number of their individuals was smaller in those plots where N containing fertilizers were used. Contrary to them, the density of D. stramonium, C. album and C. hybridum was the highest in the NPK treatments.

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The surplus of the NPK balances of Hungarian agriculture, appearing in the nutrient balance sheet is a consequence of intensive fertilization in the past. Hungary had a positive P-balance between 1960 and 1990 for 30 years, and a positive NK-balance between 1970 and 1990 for 20 years during the 20th century.Studying the long-term effects of superphosphate in a field experiment on calcareous chernozem soil, it was found that the “half life time” of residual P was 5–7 years. The trial, i.e. the P after-effect lasted for 20 years.Liming and fertilization are the main soil fertility improving considerations for acidic sandy soils. These soils are often poor in all major nutrients. Mineral fertilizers, mainly NH4NO3, acidify soil, the pH values sink in comparison to the unfertilized plot. Liming and use of dolomite powder may counterbalance the acidification.

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The current Hungarian Soil Classification System (HSCS) was elaborated during the 1960s, based on the genetic principles of Dokuchaev. It was developed before sufficient data and modern data processing tools were available and served different purposes than current users need or apply it for.The central unit is the soil type, grouping soils that were believed to have developed under similar soil-forming factors and processes. The major soil type is the highest category that groups soils based on climatic, geographical and genetic bases. Subtypes and varieties are distinguished according to the assumed dominance of soil-forming processes and observable/measurable morphogenetic properties. STEFANOVITS (1963) defined the 23 soil-forming processes that have a dominant impact on the differentiation of the 39 soil types of the system.Based on accumulated data and experience, as well as on numerical tools for defining taxonomic relationships a modernization process was carried out. The process included: linking processes to diagnostics, review and numerical study of similarities and dissimilarities of existing units, development of new central units, development of a computer assisted key, and definition of methodology to derive the lower level units. The new, 15 soil types are defined by stronger morphogenetic and measurable criteria, but with the application of legacy data and the developed key, the earlier units can be converted to the new ones, hence the value of legacy data can be preserved.

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Bedrock has an essential role in the formation of soils, it fundamentally determines mineral composition. The present research focuses on the minerals in forest soils formed in the Bükk Mountains (NE Hungary). The composition of soil minerals was in accordance with the geological features as well as with the changes in climate and vegetation, which provide a basis for tracking the past of the soil formation mechanisms (Nemecz, 2006). Thus, by studying the mineral composition the formation processes and development of the soils can be unveiled.According to the findings it can be assumed that the investigated soils, although formed primarily on solid limestone, cannot be the products of the weathering of limestone solely, as they also contain significant amounts of silicates. The major part of the soil forming materials presumably originates from earlier dust fallings or from alluvial deposits by erosion. The former assumption is confirmed by the fact that the investigated area is located at a high altitude, thus significant amounts of eroded material could only originate from a short distance, where the bedrock also consists of limestone. Further research is needed for more detailed knowledge on the mineral composition of the soils, thus on the development of the soils and the bedrock of the investigated area.

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The obtained results of the present study showed the good applicability of the van Genuchten equation for parameterizing NAPL retention data of soils (R2 = 0.99).Sufficient applicability of continuous PTFs for estimating the parameters of NAPL retention curves was found (R2 for α, n and θ s was 0.47, 0.84 and 0.86, respectively).The accuracy of parametric and point PTFs increased in case derived values of the independent variables in addition to the PSD (particle size distribution) fractions, bulk density, CaCO3 and organic matter content (R2 = 0.57–0.90 and RMSE = 2.43–5.67 vol%) were used, as compared to PTFs using only the original values of basic soil parameters as predictor variables (R2 = 0,48–0.86; RMSE = 3.56–6.83 vol%).According to the gained results, PTFs seem to be similarly accurate if the particle size distribution of soils — determined by different standard methods — are applied as independent variables.

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Three centrally edited nationwide soil maps were published in Hungary between 1953 and 1988. Each of these soil maps has advantages, but serious drawbacks as well. Authors’ hypothesis was that the drawbacks of the individual soil maps are correctable with the help of other soil maps and with ancillary data. Therefore, the oldest soil map was digitized and a study was conducted for the harmonization of data on a 266 km2 area at Keszthely (near Lake Balaton) by using the CHAID classification tree method. CORINE land cover database, digital map of surface geology, digital elevation model and derived slope categories were used as ancillary data.The seven source maps contained 7–38 categories. After the intersection of all seven maps, the resulting file contained more than 50,000 polygons and nearly 14,000 category combinations. A variable — showing the probability of the category combinations in relation to the expected areas — was calculated. This was the target variable for classification by the CHAID method, using categories of the seven original maps as independent variables.0.5% of the total area was grouped into 13 less probable classes, which represent the inaccuracies of the initial maps. 99.5% of the total area was classified into 19 classes and some of them were further subdivided on the basis of the geological map. These classes were interpreted as eight WRB soil categories. The final soil map had much better spatial resolution than any of the initial soil maps, non-soil categories were interpreted as soil categories and spatial accuracy was successfully corrected with the proposed method.

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Related to ongoing (re)forestation in the Great Hungarian Plain the short-term influence of changing land cover was studied on the grains of skeletal sandy soils. In three sampling areas with forest and grassy/arable control plots, the 0.1–0.2 mm grain size fraction of samples taken every 20 cm from the 0–100 cm sandy soil layer (totalling 22,509 grains) were separated and described with optical mineralogical microscope. In order to distinguish sand grains of forest-covered and control areas (grassland/arable land), the results of mineralogical and morphological observations were compared. It was revealed that the amount of feldspar grains is 8–9 times less than the amount of the quartz ones. The increase in the quartz/feldspar (q/fp) ratio is tied to the “consumption” of feldspars: the intense consumption of potassium by trees. Under the forest-covered fields, the number of in-situ crushed grains increased. Grains with etch pits are frequent in samples from the grasslands (except in Hajdúsámson). In samples of forest-covered areas a greatly increased number of brown grains with limonite and/or humus films were observed. The gained results can be useful in proving earlier land use in forested fields.

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Authors: Krisztina Végh, J. Csillag, A. Lukács, B Panwar and Gy. Füleky

Potassium uptake is the result of numerous simultaneous processes influencing the potassium dynamics in the rhizosphere.The presented research has focused on plant-soil interactions in the potassium supply of soil in the root environment of maize. It was assumed that: 1. roots promote the mobilization of K by the acidification of the rhizosphere soil, 2. roots increase wetting-drying cycles in their environment, and 3. soil total K content affects K release and fixation in the bulk of soil and the root environment.The promoting effect of root activity was detected on K release from soil when feldspar was added as K source to the root environment. A 2-unit reduction of soil pH multiplied K concentration in the soil solution, depending on the feldspar rate. Feldspar application significantly increased the solubility and release of potassium into the soil solution.The effect of pH reduction on the K concentration of soil solution was several magnitudes higher than that of the wetting-drying cycles both in the untreated and feldspar treated soils.Potassium uptake by maize over two generations greatly exceeded the exchangeable pool in the growing media. As a consequence of the exhaustive K uptake K release slowed down to the soil solution, as reflected in the H2O extractable K and ExK contents.Significant K fixation was detected after the K removal of maize in feldspar treated soils. On the contrary, in the treatments without plants increasing feldspar rates increased both H2O extractable K and ExK contents.One-term Langmuir equation, corrected with the originally sorbed amount of K, was fitted to measured data. The maximum amount of potassium adsorption (Kmax, mg∙kg−1) and the equilibrium constant (k) were calculated. The potassium buffering capacity was estimated at zero equilibrium concentration. Both K buffering capacity and the energy of K fixation were high for the rhizosphere soil. In rhizosphere soil samples the energy of K fixation was one magnitude higher as compared to the bulk soil and decreased substantially with feldspar addition. In soils without plants the k equilibrium constant did not change as the result of drying-wetting process only in the case of the 50% soil/feldspar mixture.In the liquid phase of the soil without feldspar application potassium concentration decreased in the one-year drying-wetting cycle, presumably it got into more strongly bounded forms in the low K status soil. In 50% feldspar enriched soil samples potassium concentration in the soil solution increased, likely as a consequence of a slow dissolution of the K content of feldspar.

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Roadside dusts were studied to explain the spatial variation, and present level of contaminant elements (including Pt, Pd and Ir) in Budapest and Seoul, the capitals of Hungary and Seoul. Road dust samples were obtained twice from traffic focal points in Budapest centre (four bridges, Margaret Island, two main railway stations, main roads) and the agglomeration (suburbs) of Budapest. Similarly, samples were collected from six sites having high traffic volumes in Seoul metropolitan city and from two control sites within the suburbs of Seoul, for comparison. The samples were analysed for contaminant elements by ICP-AES and for Pt, Pd and Ir by ICP-MS.The level of contaminant elements in road dusts were in the range of 67.6 g∙kg−1 and 0.6 μg∙kg−1 for Budapest; 50.2 g∙kg−1 and 0.5 μg∙kg−1 for Budapest suburbs; 43.5 g∙kg−1 and 3.3 μg∙kg−1 for Seoul samples. The Geo-Accumulation Indexes (GAI) of contaminant elements for Budapest, Budapest suburbs and Seoul ranged between 3.88 and −0.03; 2.74 and −0.13; 4.23 and 1.22; Pollution Indexes (PI) of the contaminant elements were in the range of 4.2 and 0.6; 0.9 and 0.4; 7.8 and 2.7; Contamination Indexes (CI) of the contaminant elements ranged from 27.1 to 3.3; 4.9 to 2.7; 21.8 to 10.2, respectively.Pt, Pd and Ir concentration levels (μg∙kg−1) were in the range of 133 and 1.9, 170 and 12.8, 4.5 and 0.4 for Budapest; 37 and 3.6, 39.4 and 11.3, 0.8 and 0.2 for Budapest suburbs; 98.5 and 25.6, 148 and 30.6, 5.6 and 2.1 for Seoul.Correlations between the Pollution Index (PI) and Contamination Index (CI) of the platinum metals in road dust samples were: −0.4090 (Ir), −0.3098 (Pd), −0.1994 (Pt) for Budapest centre; 0.8343 (Ir), −0.7652 (Pt), −0.7626 (Pd) for Budapest bridges; 0.5266 (Ir), −0.2863 (Pd), −0.0333 (Pt) for Budapest suburbs; and 0.3193 (Pd), 0.2874 (Ir), −0.0017 (Pt) for Seoul, respectively. The highest Pt, Pd and Ir levels in road dusts were found in samples originating from the major roads with high traffic volume. Significant differences in Pollution Index (PI) and Contamination Index (CI) between Seoul and Budapest were 4.0 and 5.9 for heavy traffic roads; 2.9 and 11.0 for roads with light traffic. Light traffic roads reflect that an important source of Pt, Pd and Ir in roadside environment is the automobile catalytic converter. Road dusts with high Pt, Pd and Ir levels were enriched with traffic-related contaminant elements as well.

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The aim of the present study is a better understanding of the distribution and formation of salt efflorescences by mineralogical examination. Dominant sodium sulphate and sodium chloride surface efflorescences were selected for investigation. 24 samples were collected between 1999 and 2005 from 16 sites. The soil types were solonchak and meadow solonetz.Basic soil and groundwater analyses were performed according to the standard methods. Minerals were determined by X-ray diffractometry and SEM combined with microanalysis. The evaporation experiments were carried out in a Sanyo Versatile 350 HT environmental test chamber.It was concluded that common sulphate salts form rare and unique mineral associations on salt affected soils in Hungary.Comparing the groundwater compositions and the mineral associations of surface efflorescences or that of precipitated evaporites of groundwaters, the conclusion can be drawn that groundwater composition is reflected much better by the mineral association of experimentally precipitated evaporates of the groundwater than by the mineral associations of surface efflorescences. These differences suggest that the soil matrix may have an effect on the crystallization of minerals (e.g. gypsum, thenardite) in the efflorescences. The differences also suggest that in the surface efflorescences the precipitation process does not come to the end in all cases (minerals with high solubility are missing).Concerning the data on groundwater level depths in case of different (sodium carbonate versus sodium sulphate and sodium chloride) efflorescences, there is a tendency of declining groundwater table in the sequence of these soils. This difference can be explained by the difference (increase) in the solubility of various salt minerals.It was recognized that the change in the major component of surface efflorescenes in time (i.e. the sodium carbonate and sodium carbonate chloride versus sodium sulphate efflorescences before and after 1998) can be explained by the decline of the groundwater level and by the decreasing hydromorphic influence in the lowland area during the 19th and 20th century.Finally it can be stated that the presented research — which mainly focused on mineralogical aspects — has contributed to the earlier knowledge on surface salt efflorescences, which was based only on their chemical composition.

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Authors: Dambarudhar Parida, Christophe A. Serra, Rigoberto Ibarra Gómez, Dhiraj K. Garg, Yannick Hoarau, Michel Bouquey and René Muller

We report on the synthesis of 2-(dimethylamino)ethyl methacrylate by atom transfer radical polymerization (ATRP) in tubular microreactors. Different process parameters, temperature, pressure, and shear rate, were considered to accelerate the reaction. Increase in temperature induced a faster reaction, but controlled nature of ATRP decreased past a threshold value that can be increased up to 95 °C by reducing the residence time. Positive effect of pressure was observed since significant increases in monomer conversion (+12.5 %) and molecular weight (+5,000 g/mol) were obtained. Moreover, polydispersity index was found to decrease from 1.52 at normal pressure to 1.44 at 100 bars. Benefit of pressure was more visible in smaller reaction space (smaller tube diameter). Finally, shear rate has quite an influence on the early stage of the polymerization and is expressed by an increase in the reaction rate. However, the effect was dimed for long residence times.

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Authors: Patrizio Salice, Emiliano Rossi, Alessandro Pace, Prasenjit Maity, Tommaso Carofiglio, Enzo Menna and Michele Maggini

The covalent chemistry of carbon nanostructures has put forth a wide variety of interesting derivatives that widen their potential as functional materials. However, the synthetic procedures that have been developed to functionalize the nanostructures may require long reaction times and harsh conditions. In this paper, we study the continuous flow processing of single-wall carbon nanotubes with azomethine ylides and diazonium salts and demonstrate that this approach is effective to reduce reaction times and tune the properties of the functionalized carbon materials.

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Authors: Isabelle Kraus, Shuning Li, Andrea Knauer, Marc Schmutz, Jacques Faerber, Christophe A. Serra and Michael Köhler

This paper presents a new route to the synthesis of uniform and size-controlled inorganic/organic composite microparticles by means of microreaction technology. Au-nanoparticles in the range of 3 to 14 nm are synthesized by reduction of tetrachloroauric acid, while ZnO-nanoparticles (200–2000 nm) are synthesized in a continuous-flow two-step process using microtube arrangements for microsegmented flow. Both inorganic nanoparticles have a well-controlled size and narrow size distribution. Upon surface modification, the nanoparticles are then mixed on one hand with an acrylate-based monomer and, on the other hand, with an aqueous solution of acrylamide. Both solutions were then emulsified into uniform core-shell droplets by means of a capillary-based microfluidic device. Droplet's shell was hardened through UV-induced polymerization, whereas the core led to a hydrogel upon thermal-induced polymerization. Core-shell polymer microparticles (200–300 µm) with inorganic nanoparticles selectively incorporated into the core and the shell are thus obtained as proven by extensive morphological characterizations using electronic and optical microscopies.

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In this section of the journal, the continuous-flow chemistry literature of the preceding months is presented. Included are articles published in the period October–December 2013 and January–March 2014. Some key examples are highlighted in the form of graphical abstracts. The remaining publications in the field are then listed ordered by journal name, with review articles grouped at the end.

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The real-time monitoring of the adsorption kinetic of antibody onto polyethylene terephthalate (PET) modified with gold nanoparticles (NPs) is performed into a dielectric flow microchannel. The principle is based on the microelectrode–dielectric interface excitation by a modulated voltage excitation through the dielectric layer with high frequency range. The set-up configuration using a homemade current-to-voltage converter has been developed for fast monitoring of biomolecule adsorption without direct electrical contact of microelectrodes with the microchannel flow. The change in the interfacial admittance, related to the output voltage measured through the microchip, during antibody incubation, gives information on the kinetics involved while antibodies are adsorbed at the interface. An example of adsorption on PET modified with gold NPS was taken. Experimental data were fit with the Langmuir equation and a good correlation was obtained with this latter, where the equilibrium constant, K, was found as 1.55 × 108 M−1 with a limit of detection for antibody concentration without depletion equal to 8.25 nM.

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Authors: Omar Pandoli, Tommaso Del Rosso, Ricardo Queiroz Aucélio, Alessandro Massi, Chen Xiang and Shu-Ren Hysing

A novel micromixer concept for generation of concentration gradients, inspired by a Chinese design, the traditional Chinese knot “中国结”, which features a core mesh structure allowing for a very compact design, is presented. The new concept has been designed using modern computer-aided design (CAD) and computational fluid dynamics (CFD) simulation software and validated by performing multiple experiments. The final design is found to be significantly more compact than conventional ones and allows the use of up to 15 outlet channels.

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Authors: Giancarlo Pascali, Mariarosaria De Simone, Lidia Matesic, Ivan Greguric and Piero A. Salvadori

Nucleophilic [18F]-fluorination reactions traditionally include a drying step of the labeling agent in order to achieve a successful substitution. This passage extends the time and complexity required for the whole radiotracer production, with increased hardware and detrimental effects on the radioactive recovery of such a short-lived (t ½=109 min) isotope. Because the performance of radiofluorination reactions conducted under microfluidic flow conditions have been demonstrated to be more effective in terms of reaction time and yields, we have tested the tolerance to water present in this specific reaction condition, in view of eliminating the drying step in the process. To this purpose, we tested different substrates selected from typical radiofluorination intermediates. Our results show that water could be tolerated in a microfluidic environment; in particular, we observed a slight decrease in the labeling of aromatic precursors and a significant increase for iodonium salts, whereas the radiochemical yields of the other compounds studied were virtually unchanged. These findings may open the way to the possibility of simpler and faster processes for the production of new 18F-fluorinated positron emission tomography tracers.

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The diastereodifferentiating [2+2] photocycloaddition of a chiral cyclohexenone with cyclopentene was performed in supercritical carbon dioxide (scCO2) using a flow microreactor. In all cases examined, the microreactor gave higher conversions than the batch system because of the very short path length of the microreactor. Additionally, by using the microreactor, accurate temperature control produced higher diastereoselectivity. These distinguished findings can be attributed to the synergistic effect of superior light penetration in the microreactor and the unique solvent property (clustering effect) of scCO2.

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Authors: Toshiya Yoshiiwa, Satoshi Umezu, Manabu Tokeshi, Yoshinobu Baba and Mitsuru Shindo

We report a method for the generation and subsequent reaction of ynolates in a flow microreactor via a stop-flow process. This procedure allowed for the synthesis of ynolates at ambient temperature within 11 min via a Li–Br exchange reaction with sec-butyllithium, whereas the corresponding batch process generally requires low temperature control and extended reaction times of up to 1 h. The stop-flow method is especially useful for optimizing the reaction time without having to use various microtube lengths. The resulting ynolates were applied to the olefination of carbonyl compounds and to pyrrole synthesis. These results indicate the practical utility of the ynolate reaction and should contribute to progress in flash chemistry.

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Abstract

This study is devoted to the thin-layer chromatographic demonstration of spontaneous chiral conversion of l-hydroxyproline (l-Hyp) to d-hydroxyproline (d-Hyp), and to its spontaneous peptidization, when dissolved in 70% aqueous methanol and stored at room temperature in a stoppered glass vessel. The adopted enantioseparation conditions were the same ones, as employed earlier for a successful enantioseparation of l- and d-proline. To this effect, we used microcrystalline cellulose as stationary phase and a quaternary mixture composed of 2-butanol:pyridine:glacial acetic acid:water (30:20:4:24, v/v) as mobile phase. Structural difference between proline and hydroxyproline consists in the presence of one hydroxyl group per molecule of the latter amino acid, which makes the respective enantioseparation a more difficult task. Consequently, the obtained separation effect was not a complete (i.e., a baseline) resolution of the two Hyp antimers yet a sufficient enough proof of the appearance of d-Hyp, apparently due to spontaneous chiral conversion taking place in the course of the l-Hyp solution storage and ageing period. The condensation products were discovered both in the fresh and the aged l-Hyp solution, yet in the aged sample, the condensation product yields were considerably higher than in the freshly prepared one (as convincingly demonstrated by mass spectrometry). Demonstration of the condensation products was performed with the aid of thin-layer chromatography (TLC), liquid chromatography-mass spectrometry (LC-MS), and thin-layer chromatography-mass spectrometry (TLC-MS).

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Summary

The major objective of the present work was to compare the kinetic study of alcoholic fermentations conducted in the presence of wheat supported biocatalysts in laboratory scale and in a scale-up system of 80 L and to compare these results with those reported in literature. The kinetic study of fermentation processes was accomplished with the technique of reversed flow gas chromatography (RFGC), which is a version of inverse gas chromatography. The wine yeast species used was Saccharomyces cerevisiae AXAZ-1, and fermentations were conducted between 20 and 2°C. At low temperatures, maximal ethanol productivity and fermentation rate were reduced. The rate constants, determined through a mathematical model obtained from RFGC, were higher in the laboratory scale comparing to the scale-up system at the temperatures of 20 and 15°C. However, with the reduction of temperature, both systems presented almost similar values proving the great fermentative ability of immobilized cells even at extremely low temperatures. Activation energies of the alcoholic fermentations in the two systems presented their higher values at the second phase (stationary) compared to those observed at the other two phases (growth and decline).

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Authors: K. Wróblewski, A. Petruczynik and M. Waksmundzka-Hajnos

Summary

Psychotropic drugs: desipramine, olanzapine and mitrazapine were chromatographed on cyanopropyl-silica and Diol-silica thin layers using various nonaqueous and aqueous eluents.

The best results were obtained with addition of ammonia to nonaqueous eluent on both adsorbents. On the basis of the optimization, systems for extraction from human plasma and quantitative determination of investigated drugs were selected.

RP18 encaped SPE columns conditioned and pre-eluted with acetonitrile:water:ammonium buffer at pH 8.6 (5:5:2) and eluted with methanol:water (9:1) containing 2% acetic acid were used for sample preparation with high recoveries of all investigated drugs. Diol and CN plates with mixture of 15% methanol in diisopropyl ether + 1% ammonia were used for quantitative analysis by a calibration curve method.

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Summary

A rapid, selective, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay has been proposed for the determination of aripiprazole in human plasma. The analyte and propranolol as internal standard (IS) were extracted from 200 μL of human plasma via liquid-liquid extraction using methyl tert-butyl ether under alkaline conditions. The best chromatographic separation was achieved on an Aquasil C18 (100 × 2.1 mm, 5 μm) column using methanol-deionized water containing 2 mM ammonium trifluoroacetate and 0.02% formic acid (65:35, v/v) as the mobile phase under isocratic conditions. Detection of analyte and IS was done by tandem mass spectrometry, operating in positive ion and multiple reaction monitoring (MRM) acquisition mode. The method was fully validated for its selectivity, interference check, sensitivity, carryover check, linearity, precision and accuracy, reinjection reproducibility, recovery, matrix effect, ion suppression/enhancement, stability, ruggedness, and dilution integrity. The assay was linear over the concentration range of 0.10–100 ng mL−1 for aripiprazole. The intra-batch and inter-batch precision (%CV) was ≤4.8%, while the mean extraction recovery was >96% for aripiprazole across quality control levels. The method was successfully applied to a bioequivalence study of 10 mg aripiprazole orally disintegrating tablet formulation in 27 healthy Indian subjects under fasting and fed condition. The reproducibility in the measurement of study data was demonstrated by reanalysis of 260 incurred samples.

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