Authors:Michael E. El-Kommos, Niveen A. Mohamed, Hassan R.H. Ali and Ahmed F. Abdel Hakiem
A new spectrodensitometric method was developed for the simultaneous determination of a quaternary mixture of antihyperlipidemics containing niacin, atorvastatin, and bezafibrate with either ezetimibe or simvastatin. Densitometric analysis was carried out using high-performance thin-layer chromatographic (HPTLC) silica gel 60G F254 plates as the stationary phase. The plates were developed with benzene—ACN—n-butanol (7:2:1, v/v) + 1.50%, v/v, glacial HOAC in absorbance mode at 242 nm. The retention factors of niacin, atorvastatin, bezafibrate, ezetimibe, and simvastatin were 0.17, 0.38, 0.51, 0.65, and 0.66, respectively. The method was validated according to the United States Pharmacopeia and National Formulary (USP 31—NF 26) and the International Conference on Harmonization (ICH) guidelines. Linearity ranges of all studied drugs were found to be in the range of 15–650 ng band−1 with correlation coefficient values of 0.9975 or more. Limits of detection and quantitation were 5–50 and 15–150 ng band−1, respectively. Upon applying polynomial regression to the same concentration ranges of standard solutions of all investigated drugs as well as spiked bezafibrate samples to rabbit plasma, correlation coefficient values had greatly improved. The proposed method was successfully applied for the simultaneous determination of the studied antihyperlipidemic drugs in plasma and in their pharmaceutical formulations. The developed method was utilized to study the pharmacokinetic behavior of bezafibrate and its drug—drug interaction with atorvastatin in rabbit males. This study has proven the increased myotoxicity risk upon coadministration of atorvastatin with bezafibrate.
Authors:Sadia Shakeel, Somia Gul, Aqib Zahoor, Saleha Suleman Khan, Zeeshan Ahmed Sheikh, Safila Naveed and Khan Usmanghani
The technological improvement in the structural elucidation of natural compounds has made it probable to generate appropriate strategies for the analysis and standardization of plant-based medicines. An appliance of highly oriented hyphenated techniques provides a definite tool for herbal investigations. Therefore, the present study was directed towards the standardization of biomarkers gallic acid and berberine in polyherbal formulation Entoban capsules to ensure the quality of the herbal drugs. A rapid, simple, accurate, and specific high-performance thin-layer chromatography (HPTLC) method for the quantitative estimation of biomarkers berberine and gallic acid has been developed. HPTLC was performed to evaluate the presence of gallic acid and berberine applying toulene—ethyl acetate—formic acid—methanol (12:9:4:0.5 v/v) and ethanol—water—formic acid (90:9:1 v/v), as the mobile phase, respectively. The RF values (0.58 for gallic acid and 0.76 for berberine) in both sample and reference standard were found comparable under ultraviolet (UV) light at 273 nm and 366 nm, respectively. The method developed resulted in good-quality peak shape and enabled high-quality resolution of biomarkers. The present standardization undertaken reveals compliance with the analytical procedure; therefore, it is concluded that Entoban capsule is a well-standardized product. Standardization falls under the specific guidelines of quality herbal medicine following the prerequisite for global harmonization.
Despite the fact that many researchers have developed different methods for the determination and detection of bile acid sequestrant, the analytical instruments are still quite costly, and expertise is usually required. In order to avoid the above-mentioned problems, simple, rapid, effective, and inexpensive methods to evaluate bile acid-binding are essential. The purpose of this study was to develop a simple and rapid thin-layer chromatography (TLC)—image analysis method to quantitatively determine the bile acid-binding activity of ten edible ethanolic plant extracts. The method was carried out by using TLC silica gel 60 F254 plate with the mobile phase composed of chloroform, methanol, and acetic acid (7:2:1 v/v). The chromatograms were analyzed with image analysis software (ImageJ). The method provided good linearity, accuracy, reproducibility, and selectivity for the determination of bile acid-binding activity. Litsea petiolata extract was found to show the most potent bile acid-binding activity compared to other extracts. Moreover, some extracts exhibited selective binding ability to bile acid; for example, extracts of Careya sphaerica and Polygonum odoratum could selectively bind rather to taurocholic acid than glycodeoxycholic acid. This study shows a simple method for the evaluation of potential edible plants to be used as cholesterol-reducing agents due to their bile acid-binding activity.
Authors:Dmitriy R. Gimranov, Aisylu F. Abdullina, Ekaterina V. Sevast’yanova and Yuliya Yu. Petrova
The thin-layer chromatography (TLC) procedures of metal cations, modified with amines and cationic surfactant micelles, followed by the sorption-catalytic detection of cobalt(II) and copper(II) directly into the thin layer were presented. It has been shown that the addition of hexamethylenediamine to the mobile phase acetone—3 M HCl and the impregnation of TLC plates with cetyltrimethylammonium bromide micelles and triethylamine followed by separation in 5% NaCl (pH 2.3) improves the separation efficiency of divalent metal cations mixture. A new highly sensitive detection of copper(II) and cobalt(II) after modified TLC with sorption-catalytic method was proposed. The TLC modifiers enhance the catalytic effect of copper(II) and cobalt(II) in the indicator reactions and detection selectivity. The detection limit was 0.1 ppb for copper(II) and 0.02 ppt for cobalt(II). It should be noted that cobalt(II) does not interfere with the determination of copper( II) in a 200-fold excess. The possibility of using the developed procedures in the analysis of natural water and food was shown.
Authors:Santosh R. Kote, Manoj R. Bhandarkar and Nitin L. Chutke
Imidacloprid is a member of chloronicotinyl neonicotinoid compounds. It is the most important systemic insecticide and has a wide diversity of uses: in agriculture, on turfs, on pets, and for household pests. During the last decade, Forensic Science Laboratories of Maharashtra State, India, detected a large number of human poisoning cases with imidacloprid. Since a large number of biological samples were received for toxicological analysis, thin-layer chromatography (TLC) was the method of choice. This study reports that cobalt thiocyanate was found to be a selective and sensitive spray reagent for imidacloprid in routine analysis by TLC. Imidacloprid reacts with cobalt thiocyanate which gives intense blue-colored compound. The cobalt thiocyanate reagent does not react with the organochlorine insecticides, organophosphorus insecticides, and pyrethroids. Visceral constituents (amino acids, peptides, proteins, etc.) do not interfere.
Authors:J. Wang, M. Liu, X. Tong, W. Peng, H. Cao and W. Su
Shenqi Fuzheng Injection (SFI) is a traditional Chinese medicine injection, widely used to enhance immune function of clinical cancer patients undergoing chemotherapy. In this study, a high-performance liquid chromatography-diode array detection-evaporative light scattering detection (HPLC-DAD-ELSD) method was established for quality control of SFI, which could simultaneously semiquantitatively reflect the constituents displayed in the chromatographic profile of SFI. The relative retention time and relative peak areas of the 21 common peaks related to the reference peak were calculated. The validity and advantage of this method were validated by systematically comparing chromatograms of 10 batches of SFI samples with the analytical methods of principal component analysis and angle cosine method recommended by the State Food and Drug Administration of China. Moreover, a total of 21 constituents of SFI were identified or tentatively characterized in the fingerprint via ultrafast liquid chromatography-diode array detection-quadrupole time-of-flight (UFLC-DAD-Q-TOF) tandem mass spectrometry technique on the basis of the retention time, ultraviolet spectra, fragmentation patterns, and reported literatures. All the results proved that the technique was useful in comprehensive quality evaluation of SFI and further study.
Authors:R. P. Mangukiya, R. A. Patel, P. A. Shah and K. G. Patel
Two simple, accurate, specific, and precise chromatographic methods, reversed phase high-performance liquid chromatography (RP-HPLC) and highperformance thin-layer chromatography (HPTLC), have been developed and validated for the determination of moxifloxacin hydrochloride and difluprednate in ophthalmic dosage form according to International Conference on Harmonization (ICH) guidelines. The separation of moxifloxacin hydrochloride and difluprednate in HPLC was performed on reverse phase (C18, 5 μm, 250 × 4.6 mm) column using isocratic condition, with acetonitrile, 5 mM disodium hydrogen phosphate buffer adjusted to pH 5, and methanol (50:25:25, v/v/v) as mobile phase. The flow rate for analysis was 1.0 mL min−1, and the selected chromatographic conditions effectively separated moxifloxacin hydrochloride and difluprednate with retention time of 3.6 and 6.6 min, respectively, at a detection wavelength of 254 nm. Chromatographic development in HPTLC was performed on precoated silica gel 60F254 aluminium plates with n-hexane, 6 M ammonia, and acetone (5:1.8:2, v/v/v) as mobile phase. The detection wavelength for simultaneous estimation of both drugs was 232 nm in HPTLC, and the Rf values for moxifloxacin hydrochloride and difluprednate were 2.2 and 7.1, respectively. The linear concentration range for HPLC method was 5 to 50 μg mL−1 and 1 to 10 μg mL−1; and for HPTLC method was 1200 to 2200 ng band−1 and 200 to 1200 ng band−1 for moxifloxacin hydrochloride and difluprednate, respectively. Moreover, Bartlett's test applied on the calibration peak areas revealed homoscedasticity of variance for both the methods. Both methods were validated with respect to system suitability, specificity, linearity, precision, accuracy, and robustness. The mean percentage recoveries for marketed formulation in terms of accuracy were found to be 100.53 and 100.58 for HPLC; and 100.56 and 100.30 for HPTLC for moxifloxacin hydrochloride and difluprednate, respectively. The pooled percent relative standard deviation (% RSD) value for repeatability, intermediate precision, accuracy, and robustness studies for both the methods were found to be less than 2. Result of paired t-test at 95% confidence level reveals that there is no significant difference between recoveries of drugs, using both methods. The results of the developed chromatographic methods were acceptable assuring that these methods can be successfully applied for routine quality control testing of both bulk and ophthalmic dosage forms, without any interference from the excipients.
Authors:Chunhui Dai, David R. Snead, Ping Zhang and Timothy F. Jamison
Flow chemistry has attracted significant interest in pharmaceutical development, where substantial efforts have been directed toward the design of continuous processes. Here, we report a total synthesis of atropine in flow that features an unusual hydroxymethylation and separation of several byproducts with high structural similarity to atropine. Using a combination of careful pH control in three sequential liquid—liquid extractions and a functionalized resin, atropine is delivered by the flow system with >98% purity.
Authors:K. K. Akula, B. Chandrasekaran, M. Kaur and S. K. Kulkarni
A new, rapid, and specific reversed phase high-performance liquid chromatographic (RP-HPLC) method involving precolumn derivatization with benzoyl chloride was developed and validated for the estimation of γ-aminobutyric acid (GABA) in rat brain tissue preparations. The derivatization product of GABA was identified by melting point, infrared, and proton nuclear magnetic resonance (1H NMR) spectroscopy to be n-benzoyl GABA. Various parameters which influenced derivatization and elusion were optimized. The chromatographic system consisted of C-18 column with ultraviolet (UV)—photodiode array detection ranging from 210 to 400 nm. Elution with an isocratic mobile phase consisting of 0.025 M disodium hydrogen phosphate buffer—methanol (65:35, v/v; pH 6) at a flow rate of 1 mL min−1 yielded sharp and specific peak of n-benzoyl GABA within 7 min. The method was validated with respect to the linearity, accuracy, precision, sensitivity, selectivity, and stability, wherein the benzoyl derivative of GABA showed stability for 2 months. The lower limit of detection was 0.5 nmol L−1. This novel derivatization procedure for the estimation of GABA with benzoyl chloride was also applied for rat brain tissue preparations that gave highly specific peak and good component recovery. The results show that the method for the determination of GABA by benzoylation using RP-HPLC has good linearity, accuracy, precision, sensitivity, and specificity and is simple and economical to perform.
Authors:A. Ahmad, R. M. A. Khan and K. M. Alkharfy
A rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination and quantification of glibenclamide and thymoquinone in rat plasma in the presence of internal standard (thymol). Chromatograms were developed with methanol, acetonitrile, and buffer (50:20:30, v/v/v) solvent system on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column, and pH was adjusted to 4.5 with orthophosphoric acid. Mobile phase was pumped at a flow rate of 1.5 mL min−1 with 254 nm ultraviolet (UV) detection. Validation of the method was performed in order to demonstrate its selectivity, linearity, precision, accuracy, limits of detection, and quantification (LOD and LOQ). Standard curves were linear (r2 = 0.996 and 0.999 for glibenclamide and thymoquinone) over the concentration range 0.5–50 μg mL−1. The coefficient of variation (CV) of < 6% and accurate recovery of 87.54–105.19% for glibenclamide and CV of <5% and accurate recovery of 86.08–103.19% for thymoquinone were found to be in the selected concentration range of 0.5–50 μg mL−1. The lower limits of detection and quantitation of the method were 0.109 and 0.332 μg mL−1 for glibenclamide and 0.119 and 0.361 μg mL−1 for thymoquinone, respectively. The within and between-day coefficients of variation were less than 7%. The validated method has been successfully applied to measure the plasma concentrations in a drug interaction study of glibenclamide with thymoquinone in an animal model to illustrate the scope and application of the method.
A new ultra-performance liquid chromatography method for the simultaneous determination of valsartan, amlodipine besylate, and hydrochlorothiazide in pharmaceutical formulations has been developed. Chromatographic separation was achieved within 1 min on a sub-2 μm RP18 column using an isocratic mode mobile phase consisting of a mixture of methanol and phosphate buffer (0.05 M, pH 3 ± 0.05) in the ratio 70:30 (v/v). The flow rate was set at 0.3 mL min−1 with a detection wavelength of 239 nm. The method was validated over the concentration ranges from 6.5 to 15.0 μg mL−1 for hydrochlorothiazide, from 5.0 to 12 μg mL−1 for amlodipine besylate and from 76.5 to 178.5 μg mL−1 for valsartan. Calibration plots were linear for valsartan, amlodipine besylate, and hydrochlorothiazide with a correlation coefficient greater than 0.99. Relative variation coefficients for repeatability and reproducibility were less than 3.0%. Recoveries from standard addition essay of individual component in pharmaceutical formulations were varied from 97.0% to 102.0%. The proposed method was successfully applied for the determination of valsartan, amlodipine besylate, and hydrochlorothiazide in pharmaceutical formulations with recoveries with respect to label amount in pharmaceutical formulations that varied from 98.0% to 102.9%. The low flow rate, short analysis time, and simple mobile phase composition make the method cost effective, rapid, nontedious, and successfully employed for simultaneous determination of these drugs in commercial pharmaceutical products.
Authors:Han Yueh, Anastasia Voevodin and Aaron B. Beeler
9-Hydroxymethylxanthene derivatives were optimized as a photolabile protecting group for amines in flow chemistry. 9-Methylxanthene and 2-methoxy-9-methylxanthene showed excellent deprotection yields in protic and aprotic solvents, respectively. The protecting group has good stability in acidic, basic, and thermal conditions and was successfully utilized for protection and deprotection of a variety of amines. A multistep continuous-flow synthesis of a piperazinylcarbonyl-piperidine derivative utilized the 2-methoxy-9-methylxanthene as the key protecting group utilized in an orthogonal manner.
Authors:H. M. Albishri, D. Abd El-Hady and Roaa A. Tayeb
Pharmaceutical industry concerned recently with eco-friendly analytical methods to reduce the environmental pollution. The using of toxic organic solvents for the analysis of drugs is critical. In the current work, several simple and less costly approaches such as micellar and/or cyclodextrin liquid chromatography were discussed. A new eco-friendly and simple chromatographic analysis of the ternary mixture of amiloride hydrochloride (AM), atenolol (AT), and hydrochlorothiazide (HZ) in urine by hydroxypropyl-beta-cyclodextrin (HP-β-CD) bonded stationary phase was investigated. The experimental conditions were optimized and validated based on International Conference on Harmonization (ICH) Q2R1 guidelines to detect analytes by isocratic mobile phase of phosphate buffer (5.0 mmol L−1, pH 7.0) in the presence of 0.5 mL min−1 flow rate, 25.0 °C, and 280 nm. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 0.05–20.0 μg mL−1 for AM, 0.05–50.0 μg mL−1 for AT and 0.05–50.0 μg mL−1 for HZ. The proposed method was precise, selective, and sensitive enough for the routine analysis of ternary mixture at therapeutic urine levels. The inclusion complexation and the appendant hydroxyl groups of HP-β-CD were considered the main reasons for assisting in adequate separation of the drugs. On the other hand, the presence of kosmotropic phosphate ions could solubilize the protein and could strengthen the selective inclusion of drugs inside HP-β-CD cavity. Urinary excretion studies showed that the detection of drugs is possible up to 24 h after their ingestion.
Authors:Buchi Reddy Vaddula, Swathi Yalla and Michael A. Gonzalez
A simple and rapid one-step continuous-flow synthesis route has been developed for the preparation of chromene derivatives from the reaction of aromatic aldehydes, α-cyanomethylene compounds, and naphthols. In this contribution, a one-step continuous-flow protocol in a ThalesNano H-Cube Pro™ has been developed for the preparation of these chromene derivatives. This arises from the multicomponent one-step reaction of aromatic aldehydes, α-cyanomethylene compounds, and naphthols. This flow protocol was optimized in 2-methyltetrahydrofuran, which is a more environmentfriendly solvent. The faster residence times (<2 min) coupled with elevated pressure (∼25 bar) results in an efficient, safer, faster, and modular reaction. Results obtained illustrate that this base-catalyzed reaction affords the respective chromene derivative products in very high yields. The products can then be easily purified by recrystallization, if desired.
Authors:Anne-Catherine Bédard, Jeffrey Santandrea and Shawn K. Collins
The continuous-flow synthesis of a series of 11- to 26-membered macrocycles via copper-catalyzed azide-alkyne cycloaddition is reported. The approach employs homogeneous catalysis to promote formation of triazole-containing macrocycles in good to excellent yields (65–90%) at relatively high concentration (30–50 mM) using a phase separation strategy.
Authors:M. R. Hadjmohammadi and S. S. S. J. Nazari
Description of the retention of five aromatic diamines in high submicellar liquid chromatography was carried out through several hyperbolic and logarithmic retention models using the retention data of mobile phases consisting of sodium dodecyl sulfate (SDS) (0.09–0.15 M) and methanol (50–70% v/v) at pH 3. Among the investigated models, the logarithmic retention model 0.5 log k = c0 + c1ϕ + c2[M]+ c12(ϕ[M])0.5 showed the best prediction capability and used to predict the solutes retention factors. The mean relative error of the prediction of retention factors of five aromatic diamines in the selected variables space was lower than 0.5%. Based on the best retention model, a grid search program was used to predict the retention times of each solute for all combinations of SDS and methanol concentrations in the factor space. In order to find optimal separation condition, two different chromatographic goals, analysis time and retention differences between adjacent peaks, were evaluated simultaneously using Derringer's desirability function for each mobile phase composition. At the optimal conditions (0.143 M SDS, 53% v/v methanol), a good agreement was observed between predicted and experimental values of the retention times (R2 = 0.9999 and mean relative error of 0.96%).
Authors:Alex D. Martin, Ali R. Siamaki, Katherine Belecki and B. Frank Gupton
A highly efficient continuous synthesis has been developed for telmisartan, the active ingredient in the antihypertensive drug, Micardis. This synthetic route employs a convergent strategy that requires no intermediate purifications or solvent exchanges. The key step in the reaction scheme is a Suzuki cross-coupling reaction between two functionalized benzimidazoles that is catalyzed by a solid-supported Pd catalyst. This flow-based approach utilizes a tubular reactor system coupled with a plug flow packed bed cartridge unit that produces telmisartan in an 81% isolated yield.
The composition of the essential oils obtained by hydrodistillation from flowers of Chrysanthemum coronarium L. has been investigated by gas chromatography-mass spectrometry (GC-MS). A total of 105 different constituents were identified, representing an average of 97.71–99.95% of the total oil composition. The oil obtained from flowers propagated conventionally contained the higher amounts of cis-chrysanthemol, cischrysanthenyl isovalerate, camphor, and virdiflorol, while the higher concentration of bornyl acetate, cis-chrysanthenyl acetate, and 2-(2,4-hexadiynylidene)-1,6-dioxaspiro[4.4] non-3-ene was noted in the oil obtained from flowers propagated in vitro.
Significantly higher amounts of essential oil were obtained from flowers of plants derived for in vitro propagation (0.58%) in comparison with conventional cultivation (0.50%).
Authors:K. Pramod, U. K. Ilyas, M. Singh, Y. T. Kamal, S. Ahmad, S. H. Ansari and J. Ali
High-performance thin-layer chromatography (HPTLC) method for the quantification of eugenol from nanostructured drug delivery systems was successfully developed and validated. The mobile phase consisted of n-hexane:acetone (7:3, v/v), and the densitometric scanning was performed in the absorbance mode at 280 nm. The method was valid with respect to linearity and range, accuracy, precision, specificity, detection limit (DL), and quantitation limit (QL). The linearity of the method was established by a correlation coefficient value of 0.9930 ± 0.0013. The precision was tested by checking intra-day (repeatability) and inter-day (intermediate precision) variations. The method was established to be precise by low relative standard deviation (RSD) values for different concentration of eugenol. The results of the recovery studies of eugenol from preanalyzed samples demonstrated the accuracy of the method. The specificity of the developed method for the analysis of eugenol in the nanoemulsion gel and nanoparticles samples was confirmed by comparing the spectra obtained in standard and sample analysis. The DL and QL were determined to be 31.41 and 95.17 ng band−1, respectively, for the HPTLC method. The forced degradation studies revealed on eugenol established the effectiveness of the developed and validated method. The developed and validated HPTLC method was found to be a stability-indicating one, as indicated by the results of forced degradation studies, for its use during the accelerated stability studies of the nanoemulsion gels and nanoparticles of eugenol.
In this section of the journal, the literature on continuous-flow synthesis (primarily organic synthesis and functional materials) from the period of April to June 2015 is presented. All the publications are listed and ordered by journal name, with a review article appearing at the end. With a few special issues on flow synthesis that would be appearing in other journals in coming months, the list of publications in this area is expected to grow rapidly towards the end of this year.
Authors:X. X. Yu, J. W. Wu, Z. K. Liang, M. Q. Zhao and X. J. Xu
A high-speed counter-current chromatography (HSCCC) method was established for the isolation and purification of isochlorogenic acid A from Lonicera japonica Thunb. The two-phase solvent system was composed of n-hexane:ethyl acetate: isopropanol:water (2:3:2:5, v/v/v/v). From 150 mg of the ethyl acetate fraction of L. japonica Thunb, 19.65 mg of isochlorogenic acid A was obtained in a one-step HSCCC separation, with a purity of 99.1%, as determined by high-performance liquid chromatography (HPLC). The structure was further identified by ultraviolet (UV), mass spectrometry (MS) and nuclear magnetic resonance (NMR).
Authors:María José Nieves-Remacha and Klavs F. Jensen
Ozonolysis of alkenes in liquid phase is conducted from micro scales to milli scales using a multichannel microreactor, a Corning low-flow reactor (LFR), and a Corning advanced-flow reactor (AFR). For the mass transfer limited test case of ozonolysis of 1-decene, maximum conversions that depend on the ozone availability in the gas phase are achieved regardless of the operating conditions, proving an excellent mass transfer in all three reactors. Ozonolysis of Sudan Red 7B dye provides visualization of the completion of the reaction in the glass-made AFR and LFR. Overall mass transfer coefficients are estimated to be on the order of 1/s in both the LFR and AFR, increasing with both liquid and gas flow rates. These values are within the same range observed in microchannels and one order of magnitude larger than in other conventional contactors.
Authors:Nathaniel B. Zuckerman, Maxim Shusteff, Philip F. Pagoria and Alexander E. Gash
The secondary high explosive 2,6-diamino-3,5-dinitropyrazine-1-oxide, or LLM-105, has been synthesized using a commercially available flow microreactor system. Investigations focused on optimizing flow nitration conditions of the cost effective 2,6-diaminopyrazine-1-oxide (DAPO) in order to test the feasibility and viability of flow nitration as a means for the continuous synthesis of LLM-105. The typical benefits of microreactor flow synthesis including safety, tight temperature control, decreased reaction time, and improved product purity all appear to be highly relevant in the synthesis of LLM-105. However, the process does not provide any gains in yield, as the typical 50—60% yields are equivalent to the batch process. A key factor in producing pure LLM-105 lies in the ability to eliminate any acid inclusions in the final crystalline material through both a controlled quench and recrystallization. The optimized flow nitration conditions, multigram scale-up results, analyses of sample purity, and quenching conditions for purity and crystal morphology are reported.
Authors:Olav Bleie, Michael F. Roberto, Thomas I. Dearing, Charles W. Branham, Olav M. Kvalheim and Brian J. Marquardt
The Moffatt-Swern oxidation (MSO) is a multistep, versatile, metal-free reaction by which alcohols are transformed into aldehydes and ketones. Batch MSO requires low temperatures (−70 °C) due to a highly exothermic reaction step that generates intermediates. This work shows that a rigorous investigation of the MSO in batch can be used as a stepping-stone to its implementation in a continuous-flow reactor (CFR). This work has two parts: the first part details the investigation of MSO in batch; the second covers the translation of the knowledge derived from batch to a CFR. The MSO batch reaction was performed under cryogenic conditions with real-time process monitoring. The reaction was monitored with Raman spectroscopy and could be tracked throughout the reaction. All concentrations were validated using offline high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Two configurations of the CFR were produced. Configuration 1 used the traditional batch methodology in terms of reagent addition and reaction conditions. Configuration 2 used the information derived from the batch reaction, changing the order of the reagent addition and increasing the temperature of the reactor. Real-time quantitative monitoring of chemical yield in the CFR was demonstrated via Raman spectroscopy and partial least squares (PLS) regression modeling. Reaction yield was accurately predicted every 15 s, reducing the need for chromatographic validation once the model was built. Configuration 2 was shown to perform comparably to configuration 1 at low temperature and far outperforming it at higher temperatures. Both CFR configurations performed significantly better than the batch setup in terms of temperature and yield, as was expected.
Authors:Meghan P. Negus, Andrew C. Mansfield and Nicholas E. Leadbeater
The catalyzed and uncatalyzed preparation of ethyl levulinate from levulinic acid and ethanol is presented. In the case of acid-catalyzed reactions, conditions were optimized in batch using microwave heating and then scaled-up using continuousflow processing. Both p-toluenesulfonic acid and sulfuric acid were used as catalysts, the latter proving most amenable. For the uncatalyzed reactions, all reactions were performed under continuous-flow conditions, using apparatus capable of operating at high temperature and pressure. Optimal conditions for the uncatalyzed process required heating a 3.6-M solution of levulinic acid in ethanol at 270 °C with a residence time of 30 min.
Authors:Meaghan M. Sebeika, Nicholas G. Gedeon, Sara Sadler, Nicholas L. Kern, Devan J. Wilkins, David E. Bell and Graham B. Jones
Interest in the field of antibody—drug conjugates (ADCs) has grown exponentially over the past decade. As the product pipeline grows, there is increasing need for robust chemistries which allow selective and efficient functionalization of the antibody cores for introduction of appropriate linkers and spacer groups. Under conventional bioconjugation conditions, product heterogeneity often results, and the drug-to-antibody ratios (DAR) are inconsistent. Based on our experience in protein derivatization, we have investigated the potential for continuous-flow microreactor technology to expedite and facilitate such processes. We demonstrate its potential using reagent proteins and the chimeric monoclonal antibody infliximab (Remicade™).
Authors:Levi Zane Miller, Jeremy J. Hrudka, Yuta R. Naro, Michael Haaf, Michael Shatruk and D. Tyler McQuade
A new method involving rapid flow of ligand solutions through a cartridge loaded with crystalline sodium diethylzinc hydride and subsequent isolation of three Zn—hydroxyquinoline complexes is described. The rapid-flow approach allowed the pyrophoric starting material to be used outside of the glovebox atmosphere and enabled fast mixing with ligand solutions for zinc complexation in seconds. The identity of all complexes was established by proton (1H) and carbon (13C) nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction.
This review focuses on the development of continuous rhodium-catalyzed hydroformylations in the past 15 years. Recent progresses are discussed and compared in detail, based on different types of catalyst handling including single-phase homogeneous system, multiphase system, immobilized catalysts on solid supports, supported ionic liquid phase catalyst, and scCO2—ionic liquid biphasic system.
Authors:T. S. Belal, M. M. Bedair, A. A. Gazy and K. M. Guirguis
This study presents a selective high-performance liquid chromatography (HPLC) with diode array detection (DAD) method for the simultaneous estimation of diclofenac sodium and lidocaine hydrochloride in presence of four of their related substances and potential impurities, namely, 2,6-dimethylaniline (DMA), 2,6-dichloroaniline (DCA), N-phenyl-2,6-dichloroaniline (PDCA), and N-chloroacetyl-N-phenyl-2,6-dichloroaniline (CPDCA). Some of these related substances are reported as degradation products as well. Effective chromatographic separation was achieved using Waters Symmetry C18 column, (3.9 × 150 mm, 5 μm particle size) with gradient elution of the mobile phase composed of 0.05 M orthophosphoric acid and acetonitrile. The gradient elution started with 5% (by volume) acetonitrile, ramped up linearly to 65% in 5 min then kept constant till the end of the run. The mobile phase was pumped at a flow rate of 1.5 mL min−1. The multiple wavelength detector was set at 220 nm, and quantification of both drugs was based on measuring their peak areas. The retention times for lidocaine and diclofenac were about 5.5 and 9.5 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 10–200 μg mL−1 for both drugs with correlation coefficients not less than 0.9998. The proposed method proved to be selective by resolution of the two drugs from their related substances and potential impurities. The validated HPLC method was successfully applied to the analysis of this binary mixture in the combined formulation (ampoules dosage form), and the assay results were favorably compared with a previously reported HPLC method. The proposed method made use of DAD as a tool for peak identity and purity confirmation.
Authors:R. Divišová, E. Vítová, P. Diviš, J. Zemanová and J. Omelková
An analytical method for simultaneous determination of 24 legislatively restricted fragrance allergens in various cosmetic products was developed and validated using a combination of solid-phase microextraction and gas chromatography with flame ionization detector. The divinylbenzene-polydimethylsiloxane (DVB-PDMS) fiber was evaluated as the best for extraction of all studied fragrance allergens at 40 °C and 20 min extraction time. All calibration curves showed good linearity in the range of 10−1 to 103 μg mL−1. Good repeatability and inter-day precision was determined for the proposed method. Detection limits for individual allergens ranged from 0.007 to 2.7 μg mL−1. The validated method was used to analyze real cosmetic samples. The obtained results indicated that not all of the analyzed cosmetic samples were labeled in accordance with European Cosmetic Directive.
Authors:Yizheng Chen, Jasmine C. Sabio and Ryan L. Hartman
Flow chemistry has emerged as the enabling field of high-throughput, data-driven discovery, and process chemistry, yet solids handling remains its key challenge. Insoluble salt by-products can stop flow, fluctuate reagent concentrations in reactors, and cost unexpected time and materials consumptions. The clogging of perfluoroalkoxy (PFA) tubing, stainless steel (SS) tubing, and a silicon microreactor by NaCl during a Pd-catalyzed amination using XPhos ligand was each studied. Our goal of understanding the appropriate reactor design provides in-depth analyses of constriction and mechanical entrapment. Calculations of Stokes number (St)>1 revealed that NaCl particle depositions were independent of the reactor materials. Analyses of the clogging time’s dependence on the residence time (τ) and particle volume fraction (ϕ) discovered commercial tubing to be inadequate for the decoupling of the kinetics. The results prescribe why fabricated microreactors with on-chip analytics, particle formations and dissolutions, and without fluidic connections are solutions to discover and develop ubiquitous reactions that form inorganic salt by-products.
Authors:Hanna Barchanska, Marcin Sajdak, Anna Wróbel and Celina Pieszko
The aim of this work was to determine the correlations between retention factors of selected triketone herbicides (mesotrione MES, sulcotrione SUL, and tembotrione TEMB), their derivatives (AMBA, MNBA, CMBA, CHD, and TEMB MET), and their physicochemical properties as well as chemical structures. Moreover, the comparison of chromatographic lipophilicity scales by means of principal component analysis (PCA) and hierarchical cluster analysis (HCA) was conducted. All experiments were conducted using thin-layer chromatography (TLC). Acetonitrile and 0.1% formic acid in water, as well as the mixtures of the above-mentioned solvents in the ratios 30:70, 50:50, and 70:30 (v/v) were used as mobile phases. Silica gel modified with alkyl chains of different lengths (C–2, C–8, C–18) as well as hydroxyl (OH) and amine (NH2) groups were employed as stationary phases. HCA and PCA were employed to investigate the influence of chemical properties and structures of triketones and their derivatives on chromatographic separations. The chemometric analysis applied in this study enables classification of the chemical and structural properties of the investigated compounds using solely information from thin-layer chromatography.
Authors:Nouruddin W. Ali, Eglal A. Abdelaleem, Ibrahim A. Naguib and Fatma F. Abdallah
A validated, sensitive, and highly selective stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been adopted for the quantitative determination of pyridostigmine bromide in the presence of its alkaline-induced degradation product and in pharmaceutical formulations. 3-hydroxy-N-methyl pyridinium bromide (3-OH NMP) is the metabolite, impurity, and alkaline-induced degradation product of pyridostigmine bromide (PB). Pyridostigmine bromide and its alkaline-induced degradation product were separated on silica gel HPTLC F254 plates using methanol–ethyl acetate–triethyl amine–glacial acetic acid (9:1:0.5:0.05 by volume) as the developing system followed by scanning of the separated bands at 270 nm over a concentration range of 2–10 μg band−1 with mean percentage recoveries of 99.84% (SD 1.384). The proposed method was successfully applied to the analysis of pyridostigmine bromide both in bulk powder and in pharmaceutical formulation without interference from other dosage form additives. The results obtained by the proposed method were statistically compared with those obtained by the reported HPLC method with no significant difference regarding both accuracy and precision, indicating the ability of the proposed method to be reliable and suitable for routine analysis of a drug product.
Authors:Bhagyashri Kumbhalkar, Shubhada Tamhankar and Anuradha Upadhye
Bottle gourd (Lagenaria siceraria (Molina) Standl.) is an important vegetable cucurbit cultivated in the warmer parts of the world. Forms bearing nonbitter fruits are used as vegetables, while those with bitter fruits are used in the Indian Traditional System of Medicine. The presence of cucurbitacins is probably the only distinguishing feature between the two forms. The present communication describes the development and validation of a high-performance thin-layer chromatographic (HPTLC)–densitometric method for the estimation of cucurbitacin B in bottle gourd using the International Conference on Harmonization (ICH) guidelines. The complete methanol extracts obtained by accelerated solvent extraction (ASE) were resolved in the mobile phase chloroform– methanol (9.5:0.5, v/v), wherein cucurbitacin B was resolved at RF 0.67 ± 0.02. Linear relationship was obtained between the values 200 and 1200 ng per spot (r = 0.9909). The limit of detection and limit of quantification were 40 and 200 ng per spot, respectively. The recovery of compound varied between 94 and 96%. Using the developed HPTLC method, the cucurbitacin B content in the vegetative parts (VP) and fruits (F) of the bitter form was found to be 0.017% and 0.062%, respectively, while it was not detected in the nonbitter form. The application of the method to study the accumulation of cucurbitacin B during progressive developmental stages of fruits of both forms revealed an increasing content of cucurbitacin B from 0.001 to 0.085% during the fruit development in the bitter form. In investigations of market samples, cucurbitacin B was detected in two out of six samples indicating admixture of bitter and nonbitter forms. To the best of our knowledge, this study is the first report of the evaluation of bitter and nonbitter forms of bottle gourd for cucurbitacin B using HPTLC. The developed method may be applicable in the routine quality control of marketed products and formulations of bottle gourd.
Authors:Jin Wang, Xianshuang Cao, Yadong Qi, Vanessa Ferchaud, Kit L. Chin and Feng Tang
The leaves of Hibiscus sabdariffa L. are one of the sources of food and traditional medicine. A combination of high-performance thin-layer chromatography (HPTLC) bioautographic assay with mass spectrometry (MS) has been performed to screen and identify the antioxidant compounds in the leaves of H. sabdariffa L. The crude extract of H. sabdariffa L. was separated on silica gel 60 HPTLC plates in an automatic developing chamber (ADC2) with toluene–ethyl acetate–formic acid–methanol (6:6:1.6:1, v/v) as the mobile phase. Antioxidant bands were visualized by dipping in 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagent. Five antioxidant compounds were identified as neochlorogenic acid (1), chlorogenic acid (2), cryptochlorogenic acid (3), rutin (4), and isoquercitrin (5), which could be the predominant contributors to the antioxidant activity of the leaves of H. sabdariffa L. Furthermore, principal component analysis (PCA) was carried out to discriminate ten accessions of H. sabdariffa L. using an image-processing software. This simple HPTLC fingerprint assisted by PCA can be used as a reliable method for the discrimination of different accessions of H. sabdariffa L.
Authors:Jing Zhang, Mei Meng, Ying Jiang, He Zhang and Fang Wang
A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of astragaloside IV and formononetin in Radix Astragali. Samples were employed to degrease the materials by petroleum ether (boiling point: 60–90°C) and extracted by methanol, and then were alkalized and extracted with n-butanol saturated with water. Separation was achieved on HPTLC plates using petroleum ether (boiling point: 60–90°C) and n-butanol saturated with water-glacial acetic acid as the mobile phase, the results of which were compared with HPLC. The well-resolved peaks for astragaloside IV and formononetin were observed at RF values 0.43 ± 0.02 and 0.75 ± 0.02, respectively. The calibration curves were found linear with a wide range of concentration 1.01–10.10 μg μL−1 with good correlation coefficient for astragaloside IV and formononetin. The method was validated for linearity, precision, reproducibility, accuracy, and limits of detection and quantification. This simple, rapid, sensitive, economic, and reliable HPTLC method is suitable for the routine quantitative analysis and quality control of traditional Chinese medicines (TCMs) such as Radix Astragali, which can be applied for the quality control of saponins and flavonoids in other plants or extracts.
Authors:Aziz Ahmed, Sayeed Ahmad, Mahfooz Ur-Rahman, Tamboli E. Tajuddin, Ranbir Verma, Mohd Afzal and Prahlad Singh Mehra
Bacoside A, a triterpenoid saponin, is a major constituent isolated from Bacopa monnieri (L.) Wettst. (Scrophulariaceae), used as a memory enhancer. Bacoside A and B are active ingredients in Bacopa herb and have antioxidant and hepatoprotective activities
A new rapid, simple, and economical high-performance thin-layer chromatographic (HPTLC) method was developed and validated for densitometric quantitative analysis of bacoside A in powdered leaves from different geographical regions of India.
Materials and methods
An amount of 10 mg mL−1 methanol extract of powdered leaves from different geographic regions was used for sample application on precoated silica gel 60 F254 aluminum sheets. Standard bacoside A (1 mg mL−1) was used for calibration curve. HPTLC separation was performed on percolated silica gel aluminum plate 60 F254 (20 cm × 10 cm with 0.2 mm thickness) as a stationary phase using ethyl acetate–methanol–water (4:1:1) as the mobile phase. Quantification was achieved by densitometric analysis at 598 nm over the concentration range of 500–4000 ng band−1.
Compact and well-resolved bands for bacoside A from powdered leaves of different geographic regions were found at retardation factor (Rf) 0.53 ± 0.02. The linear regression analysis data for calibration curve showed good linear relationship with regression coefficient r2 = 0.9996 and r2 = 0.99810 with respect to peak area and peak height. The method was validated for precision, recovery, and robustness as per the International Conference on Harmonization (ICH) guidelines. Variation in quantitative analysis of bacoside A in powdered leaves sample from different geographic regions was found by HPTLC method.
Discussion and conclusion
The highest and lowest content of bacoside A in powdered leaves sample from Jammu and Kerala regions, respectively. The variety of B. monnieri in Jammu is superior to other regions of India. The proposed developed HPTLC method can be applied for the quantitative determination of bacoside A in powdered leaves of plant and its formulation.
Authors:Liangmiao Ou, Qiaoli He, Zhihong Ji, Keao Li and Shuge Tian
A simple, rapid, and effective high-performance thin-layer chromatographic method has been developed for the analysis and quantitative determination of ellagic acid, gallic acid, and methyl gallate in the galls of Quercus infectoria Olivier. Analysis was performed on silica gel G F254 TLC plates with toluene–ethyl acetate–formic acid (6:4.5:2, volume ratio) as the mobile phase. Densitometric detection was performed at 300 nm. The method was validated for linearity, precision, stability, recovery, and robustness. The limits of detection (LOD) and quantification (LOQ) were determined. The calibration curves showed a good linearity for ellagic acid, gallic acid, and methyl gallate with correlation coefficients of 0.9995, 0.9997, and 0.9996, respectively. The LOD and LOQ values were in the nanogram range for all three compounds. The average recovery was >96%. The amounts of ellagic acid, gallic acid, and methyl gallate in the galls of Q. infectoria were determined by using calibration graphs. The developed method is simple, with good precision, stability, recovery, and robustness. This method can satisfy the requirements for quantitative determination and provides a new and effective way for the quality monitoring and evaluation of galls of Q. infectoria.
Authors:Azza Aziz Moustafa, Hesham Salem, Maha Hegazy and Omnia A. Mahmoud
Simple, accurate, precise, sensitive, and validated high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC)–densitometric methods were developed for the simultaneous determination of carbinoxamine (CAR), pholcodine (PHL), and ephedrine (EPH) in antitussive syrup. In method A, reversed-phase (RP)-HPLC analysis was performed on an Inertsil CN-3 column (250 mm × 4.6 mm, 5 μm), using a mobile phase consisting of acetonitrile–distilled water (pH 3.5) using orthophosphoric acid in the ratio 70:30 (v/v) and flow rate of 1.5 mL min−1. Quantitation was achieved with ultraviolet (UV) detection at 220 nm. In method B, TLC analysis was carried out on an aluminum-backed sheet of silica gel 60 F254 layer using chloroform–propanol–ammonia (6:4:0.1, v/v) as the mobile. Quantification was carried out with UV detection at 245 nm. The validation of the proposed methods was applied according to the International Conference on Harmonization (ICH) guidelines. The suggested methods were successfully applied for the determination of the cited drugs in bulk powder and commercial dosage form.
Authors:Bokka Ramesh, Vanka Uma Maheswara Sarma, Katragunta Kumar, Katragadda Suresh Babu and Potturi Sita Devi
The isolation and characterization of bioactive compounds from medicinal plants is usually a significant challenge in phytochemical analysis because of the natural chemical complexity of plant extracts. However, there exists a need for analytical tools which can quantitatively separate and characterize the components from these biosources with greater chromatographic selectivity and lesser analytical run times that facilitate the evaluation with enhanced separation profiles. Hyphenation of thin-layer chromatography (TLC/HPTLC) with mass spectrometry (MS) is an alternative for screening herbal extracts because of its rapid analysis and ability to aid structural characterization with powerful analytical capacity. The aim of the present study was to develop a sophisticated analytical method which utilizes HPTLC–MS coupling for the chromatographic profiling and evaluation of the therapeutically important genus Piper (Piperaceae). In this study, six marker compounds, namely, trichostachine, piperine, 4,5-dihydropiperlonguminine, guineensine, pellitorine, and sesamin were analyzed and quantified in extracts of Piper nigrum L. and compared with those of Piper longum L. and Piper chaba Hunter. All the samples tested showed similar phytochemical profiles, but the contents of the active ingredients varied. Additionally, HPTLC–MS further allowed confirming the identification of the constituents in the analyzed samples with greater chromatographic selectivity where HPTLC facilitated a selective chromatographic resolution, while MS offered an efficient characterization of the target compounds in one analytical run. The study finds a potential utility in adopting HPTLC–MS as a rapid and high throughput method for the efficient quantification and identification of marker compounds from medicinal plants.
Authors:Viktor Misuk, Andreas Mai, Yuning Zhao, Julian Heinrich, Daniel Rauber, Konstantinos Giannopoulos and Holger Löwe
Fast mixing is essential for many microfluidic applications, especially for flow at low Reynolds numbers. A capillary tube-in-tube coaxial flow setup in combination with a glass microreactor was used to produce immiscible multiphase segments. These double emulsion segments are composed of an organic solvent as the shell (outer) phase and a completely fluorinated liquid (Fluorinert® FC-40) as the core (inner) phase. Due to the higher density of the core droplets, they are responsive to changing their position to the force of gravity (g-force). By gently shaking or jiggling the reactor, the core drop flows very fast in the direction of the g-field without leaving the shell organic phase segment. Furthermore, by shaking or jiggling the reactor, the inner droplet moves along the phase boundary of the shell segment and continuous phase. Computational fluid dynamics (CFD) calculations show an enhancement of the internal circulations, i.e., causing an exceptional mixing inside of the shell segment. For reactions which are limited by mass transfer, where the conversion significantly increases with improved mixing, these recirculation zones are decisive because they also accelerate the mixing process. With a common phase-transfer catalytic (PTC) etherification of phenol with dimethyl sulphate, a remarkable increase of yield (85% gas chromatography [GC]) could be achieved by applying active mixing within a segment in continuous flow.
Authors:Iva Rezić, Domagoj Mudronja, Marko Obranović, Tonči Rezić and Ksenija Škarić
The main goal of this work was to apply thin-layer chromatography (TLC) in the investigation of different binding media (proteins, sugars, waxes, resins, and oils) found on samples of two mummifed bodies of saints originating from 1200 AD and 1500 AD. The historical samples were compared by testing them for the presence of different inorganic and organic compounds. The chemical methods used were TLC, microscopy, X-ray fuorescence spectrometry, and Fourier transformed infrared spectroscopy. The detected similarities in the composition of the binding media coatings on two mummies indicated that those were not applied immediately after death but much later showing resemblance in their preservation treatments. Moreover, according to the composition of the materials detected, the coatings did not seem to have had considerable impact on the mummifcation of the bodies. The combination of TLC and other chemical methods proved to be an effective and low-cost tool for obtaining valuable information during the archeological investigations.
Napjainkban mind gyakrabban teszik fel azt a kérdést, hogy az intenzív agrotechnika és az ilyen körülmények között termesztett fajták genetikai adottságai következtében megváltozik-e a takarmányozási/táplálkozás-élettani minőség. A válasz megadását több tényező is nehezíti, hiszen nehéz évtizedekig archiválni a mintákat és azután egy időpontban ugyanazzal a műszerrel, módszerrel a mérést elvégezni. A szerzőnek, lehetősége volt arra, hogy a rendelkezésére álló, 1974–2006 között atomabszorpciós spektrofotométerrel, majd 1988-tól ICP-OES-sel, később ICP-MS-el mért minták adatait ilyen szempontok szerint is feldolgozza. Ehhez még sikerült néhány mintát elemeztetnie az 1839 és 1950 közötti évekből, a hazánkban fellelhető mintagyűjteményekből. A mért ásványielem-tartalmakat (P, K, Ca, Mg, Fe, Mn, Zn, Cu) a hazai irodalmi adatokkal hasonlította össze.
Az 1974–2006 között kapott nagyszámú adatot összevetve az 1839–1936 közötti eredményekkel megállapította, hogy a Cu, a Zn, a Mn és a Mg esetében figyelhető meg csökkenés. Ez a csökkenés az elemeként változott, hiszen a mangánnál és a réznél több mint 25%-os, míg a cinknél és a magnéziumnál pedig 15%-os. Ezzel szemben a Ca-tartalom mintegy 150 mg·kg-1-mal magasabb, míg a P-tartalom nem változott. A P- és K-tartalomban a korábban BARDÓCZ és PUSZTAI (2013) által kö-zölt nagymértékű csökkenés nem figyelhető meg.
A bioszén anyagában a tápanyagok három jellemző, hasznosulási sebességüket meghatározó formában lehetnek jelen. A hamu frakcióban lévő elemek gyakorlatilag azonnal, a labilis frakcióban lévők a mineralizáció után heteken, hónapokon belül, míg a perzisztens frakcióban lévők csak évszázadok során szabadulnak fel. A frakciók aránya a bioszén előállítási körülményeitől függ, így ezek alapvetően befolyásolják a végtermék tápanyag-szolgáltató képességét.
A foszfor és a kálium mindhárom frakcióban megtalálható, így a bioszén ezen elemek közvetlen forrása lehet a talajban. A nitrogén viszont csak a labilis és a perzisztens frakcióban található meg — koncentrációja a hamuban gyakorlatilag nullának tekinthető –, így a bioszén saját N-tartalmából növénytáplálási szempontból csak a labilis frakcióban lévő vehető számításba rövidtávon. Ezt figyelembe véve a bioszén alkalmazása mellett a nitrogén más forrásból történő pótlása szüksé-ges.
A bioszén azonban nem csak közvetlenül, saját tápelem-tartalma folytán, hanem közvetetten a talajtulajdonságokra (pH, kationcsere-kapacitás, vízgazdálkodás, stb.) és a mikrobiológiai folyamatokra gyakorolt hatása révén is befolyásolja a talaj táp-anyag-szolgáltató képességét. A közvetlen és közvetett hatás a tápanyagok felvehe-tősége szempontjából gyakran ellentétes irányú. A bioszénnel bevitt elemtartalom révén a talajban mért összes mennyiség megnőhet, de a fokozottabb tápelem-megkötő képesség miatt a könnyen felvehető, vízoldható mennyiségek lecsökken-hetnek. A két hatás eredője határozza meg, hogy egy adott elem felvehetősége javul-e a talajban.
Hosszú távon azonban csakis a közvetett hatásokkal számolhatunk, így a bioszén alkalmazásánál ezeket szem előtt tartva kell mérlegelni és dönteni a felhasználásáról.
A bioszén olyan mértékű alkalmazása, hogy az a Föld klímája szempontjából befolyásoló tényezőként jelentkezzen, egyelőre meglehetősen távolinak tűnik. A talajjavítási, tápanyag-utánpótlási szerepkörben azonban érdemes a bioszénnel foglalkozni. Az intenzív növénytermesztés során a bioszénnel történő tápanyag-utánpótlás nem biztosítható, de a konvencionális trágyaszerekkel együtt alkalmazva hasznos adalékanyag lehet, mivel azok hatékonyságának fokozása mellett talajjavító hatása is érvényesülni tud. A bioszén ezáltal a mezőgazdasági termelésben hosszú távú előnyöket biztosíthat.
A rendelkezésre álló szakirodalmi hivatkozások a bioszén széleskörű felhaszná-lási lehetőségeit jelzik a talaj-növény-mikroba kölcsönhatás alakulására. A bioszén kedvezően befolyásolhatja a talajok fizikai-kémiai tulajdonságait, pl. vízháztartását, agyag- és szervesanyag-tartalmát, a kémhatását, a N- és P-tartalmát, a mezo- és mikroelemek mennyiségét és porózus szerkezete miatt annak levegőzöttségét, az oxigéntartalmát vagy az oxigén relatív mennyiségét a pórustérben.
A növénytáplálásra kifejtett kedvező hatások közvetlenül és közvetve is meg-nyilvánulhatnak. A mikroorganizmusok intenzívebb szaporodása a bioszénnel kezelt területeken az irodalmi adatok alapján jól megalapozottnak tekinthető. A bioszén kiszáradástól való felületi védelmet, oxigéndúsabb környezetet, és adszor-beált szerves anyagokat is jelent a mikroorganizmusoknak; gombáknak és baktéri-umoknak egyaránt. A jobb mikrobiális ellátottság eléréséhez a talaj a fizikai-kémiai tulajdonságok mellett kedvező hőmérséklet és a kémhatás is hozzájárul.
A bioszén növénytermesztési technológiákba történő integrálásának eredményei így leginkább rövidtávon, de termésnövekedésről adnak számot. A növénytermesztés szempontjából hasznos mikroszimbionta nitrogénkötő baktériumok valamint a foszformobilizáló mikorrhiza gombák mennyisége és aktivitása ugyanakkor erősen dózis és termékfüggő. A növény-mikroba szimbiózis hatékonysága a leginkább szükséges és kritikus környezeti stressz-körülmények között rosszabbodhat. Aggó-dásra ad okot a helytelenül használt nagy bioszén-dózisok tápanyag- és/vagy vízle-kötő tulajdonsága és nem utolsó sorban a talajeredetű patogén mikroorganizmusok fokozott felszaporodási lehetősége is.
A bioszén tehát olyan értékes eszköz lehet a kezünkben, aminek előnyeit csak a megfelelő talajfizikai, -kémiai és -biológiai vizsgálatokra alapozottan, odafigyelés-sel és kellő szakmai ismeretekkel együtt használhatunk ki jól és biztonságosan.
Authors:Anita Lepossa, Sándor Hoffmann and Szabolcs Nagy
A talajokban élő cianobaktériumok és eukarióta algák edafonban betöltött szerepe kulcsfontosságú. Eddig megismert kölcsönhatásaik a talaj más szervezeteivel és a magasabb rendű növényekkel, valamint hozzájárulásuk a talajok mikroszerkezetének kialakulásához és a nitrogénellátáshoz a legismertebbek.
A talajalgák mennyiségi és minőségi kimutatására meglehetősen kevés közvetlen és közvetett sejtszámolási módszer és adat áll rendelkezésre.
Jelen munkánkban Ramannféle barna erdőtalajon őszi búza, bíborhere, kukori-ca és szója parcellákból gyűjtött talajminták cianobaktérium és eukarióta mikroalga sejtszám vizsgálatát végeztük el egy — ezen a téren még újnak számító — nagysebes-ségű, automatizált sejtanalitikai módszer, az áramlási citometria alkalmazásával.
A négy növénykultúrából 2013 júliusában, Keszthelyen, a felszíni öt centiméte-res talajrétegből hat ismétlésben vett talajmintákból vizes szuszpenziót készítettünk, majd mértük azok aktív algasejt-tartalmát. A cianobaktériumokat és az eukarióta algákat klorofill-a és fikoeritrin autofluoreszcencia alapján különböztettük meg a szuszpenzió egyéb elemeitől. A mérésekhez Beckman Coulter FC–500 áramlási citométert használtunk, mintánként öt perc futtatási idővel. A műszer által rögzített eseményszámból következtettünk az algasejtszám-értékekre.
A citométeres ábrákon — megfelelő beállítások után — jól elkülönülő alga sejtpopulációk jelentek meg. Valamennyi mintában a cianobaktériumok domináltak, legalább 60%-os aránnyal. A kukorica talajában mutattuk ki a legnagyobb alga jelenlétet (2,4·105 sejt·g−1 száraz talaj), míg a búzáéban a legkevesebbet, alig 50%-ot (1,1·105 sejt·g−1 száraz talaj). A cianobaktériumok becsült sejtszámát tekintve a kukorica és a szója talajában jelentősen nagyobb abundancia mutatkozott a bíborhere és őszi búza talajához viszonyítva. Szignifikáns különbséget találtunk a becsült eukarióta alga sejtszámban a kukorica- és szója talaja között, a kukorica javára.
Eredményeink igazolták, hogy az áramlási citometria megfelelő és hiánypótló módszer lehet a talajok kvantitatív mikrobiológiai vizsgálatai során, különös tekin-tettel a fotoszintetizáló szervezetekre.
Authors:Omnia A. Mahmoud, Maha A. Hegazy, Hesham Salem and Azza A. Moustafa
Simple, sensitive, selective, and precise stability-indicating thin-layer chromatography (TLC)—densitometric and reversed-phase high-performance liquid chromatography (RP-HPLC) methods were developed and validated for the determination of citicoline sodium (CT) in the presence of its alkaline degradation products (CT Deg.) and in pharmaceutical oral solution. TLC—densitometry employs aluminum TLC plates precoated with silica gel 60 F254 as the stationary phase and ammonia—ethyl acetate—triethylamine (6:3.5:0.5, v/v) as the mobile phase to give compact spots for citicoline sodium (RF = 0.35) and its degradation product (RF = 0.1); the chromatogram was scanned at 272 nm. RP-HPLC utilizes a C18 column and a mobile phase consisting of methanol-water-acetic acid (60:40:0.1, v/v); the pH level was adjusted to 4 using 0.1% orthophosphoric acid, at a fow rate of 1 mL min−1 for the separation of citicoline sodium (tR = 1.801) and its degradation product (tR = 3.422). Quantitation was achieved by ultraviolet (UV) detection at 272 nm. Citicoline sodium was exposed to alkaline hydrolysis, and a comparative study was carried out to show the advantages of the proposed chromatographic methods in determination of citicoline sodium in the presence of its alkaline degradation products. The chromatographic methods were developed and validated as per the International Conference on Harmonization guidelines. As the methods could effectively separate the drug from their degradation products, these techniques can be employed as stability-indicating methods that have been successively applied to pharmaceutical formulations without interference from the excipients.
Authors:Sebastiaan A. van den Berg, Raoul A.M. Frijns, Tom Wennekes and Han Zuilhof
Alcohol protection and deprotection reactions, catalyzed by solid-supported sulfonic acid, have been investigated under continuous-flow conditions. Primary, secondary, benzylic and phenolic alcohols can be protected under these conditions by tetrahydropyranyl and several silyl ether moieties, generating synthetically useful amounts of material in short time. Furthermore, the described setup can be used to deprotect protected alcohols and be used in selective protection reactions. Because the solid-supported acid catalyst is continually reused in a packed-bed approach, workup is greatly simplified and in most cases only solvent removal is necessary, while reaching high turn-over numbers.
Authors:Omer A. Basudan, Perwez Alam, Nasir A. Siddiqui, Mohamed F. Alajmi, Adnan J. Alrehaily, Saleh I. Alqasoumi, Maged S. Abdel-Kader, Prawez Alam and Abd El Raheim M. Donia
A simple and sensitive high-performance thin-layer chromatographic (HPTLC) method was developed for the evaluation of biomarker β-amyrin in the leaves of fve different species of genus Ficus (Ficus carica, Ficus nitida, Ficus ingens, Ficus palmata, and Ficus vasta) grown in the Kingdom of Saudi Arabia. Chromatography was performed on glass-backed silica gel 60 F254 HPTLC plates with solvents toluene–methanol (9:1, v/v) as the mobile phase. After development, the HPTLC plate was derivatized with p-anisalde-hydereagent to give well-resolved and compact spot of β-amyrin. Scanning and quantifcation were done at 550 nm. The system was found to give compact spot for β-amyrin at RF = 0.58. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.998 with respect to area in the concentration range of 100–900 ng. The regression equation for β-amyrin standard was found to be Y = 5.835X + 87. The precisions (n = 6) for β-amyrin were found to be 1.64–1.77% and 1.68–1.84%, respectively, for intra-day and inter-day batches, and the recovery values were found to be 97.6–98.3%. β-Amyrin was found to be present in three species, i.e., F. carica (0.29%, w/w), F. nitida (0. 5 4% w/w), and F. p almata (0.31%, w/w), while it was absent in F. vasta and F. ingens. The statistical analysis proves that the developed method for the quantifcation of β-amyrin is reproducible; hence, it can beemployed for the determination of β-amyrin in plasma and other biological fuids as well as in fnished products avai lable in the market.
Authors:Tibor Tóth, Sándor Molnár, Kitti Balog and Zsófia Bakacsi
A Duna–Tisza közi hátságban az elmúlt évtizedekben jelentős változások zajlottak le a terület hidrológiai viszonyaiban történt változások miatt. A hátság egyik legérzékenyebb természeti képződményei a szikes tavak. Ezek állandóságához nem csupán megfelelő vízellátottság, de megfelelő mennyiségű és minőségű oldható só is szükséges. A hátságban zajló regionális és lokális vízforgalom tér- és időbeli koncepcionális modellje alapján, a Szappanostó példáján számszerűen jellemeztük az elmúlt 31 év folyamán a talajok sótartalom-változását. Ehhez négy, 1983-ban már vizsgált mintapontban a talajvíz szintjét, összetételét és a talajt is elemeztük — lehetőség szerint ugyanolyan módszerrel.
A területen a talajvízszint süllyedt és a felszíni vízborítás jelentősen csökkent, valamint csökkent a talajvíz sótartalma, lúgossága és nátriumtartalma. A talaj felszínközeli rétegeiben csökkent a sótartalom, a pH és a nátriumtartalom.
A CaCO3-tartalom mélységi lefutási görbéi átrendeződtek, ebben a kilúgzás mellett a tómederben és a partján működő ráhordás/lehordás is jelentős szerepet játszhatott.
A tómedret teljesen benőtték a növények, az 1983-ban jellemző sókedvelő, nagy sótartalmat is tűrő növényekhez képest 2014-re a kis talajsótartalmat kedvelő növé-nyek terjedtek el, teljesen beborítva a felszínt. Megnövekedett a talaj humusztartal-ma és kiterjedt a füvek kaszálása.
Authors:He Zhang, Mei Meng, Li Chen, Fang Wang, Jing Zhang, Ying Jiang and Wen Wang
The newly emerged chromatographic fngerprint analysis represents a rational approach assessment of Traditional Chinese Medicine (TCM) and its preparations. In the present paper, a quick and reliable analytical method was developed for the quality assessment of QiYi capsules (QY) using high-performance thin-layer chromatography (HPTLC) with the reference of Tripterygium wilfordii. The unique properties of the HPTLC fngerprint were validated by analyzing 10 batches of QY samples. The 9 common peaks of the HPTLC images of QY and the different RF and peak area ratios of the chemical distribution could directly discern the stability by comparison of 10 samples, and also, the 9 common peaks were selected to evaluate the similarities of QY; the similarities of 10 batches of QY were more than 0.960, which indicated a standardized consistency and reliable quality of QY. Therefore, the newly developed HPTLC fngerprint method provided an easy way for sample characterization and differentiation; it allowed for the quality assessment of QY capsules with the reference of T. wilfordii.
Authors:Alastair Baker, Michael Graz, Robert Saunders, Gareth J. S. Evans, Ilaria Pitotti and Thomas Wirth
Rapid alkylations of thiols are performed in a packed-bed flow reactor where potassium carbonate acts as a heterogeneous base in anhydrous solvents at ambient temperature. The reaction also has a high efficiency as the removal of the solvent is the only work up required to isolate the product. The products can be used in a subsequent oxidation which was performed sequentially in semibatch mode. The alkylations of phenol and benzyl amine have been demonstrated on an array of bases, but higher temperatures and longer reaction times are required than with thiols.
Közismert, hogy a tápanyag-gazdálkodásban a foszfor problematikája kiemelt szerepet játszik, mivel a foszfor tápanyagellátás nem csupán a talaj növények szá-mára felvehető P-tartalmát növelheti, hanem egy kritikus koncentráció fölött környezeti kockázattal járhat. A hatékonyságot a környezetkímélő tápanyag-gazdálkodásban növelni kell, a műtrágya hatóanyag érvényesülés javításán és a környezet terhelését okozó veszteségek csökkentésén keresztül. A talajok foszfordinamikájának számszerűsítése ebben kulcsszerepet tölt be.
Kísérletsorozatunkban tenyészedény- és inkubációs kísérleteket végeztünk tartamkísérletek talajaival, tanulmányoztuk a különböző talajtípusok foszfordinamikájának mennyiségi viszonyait, az egyes talajtípusok foszfor retencióját és szolgáltató képességét. Célunk volt a műtrágyával kijuttatott foszfor utóhatásának, valamint az oldhatósági viszonyok megváltozásának tanulmányozása is. Dolgozatunkban kísér-letsorozatunk azon részének eredményeiről számolunk be, amelyet Keszthelyen, Ramannféle barna erdőtalajon (homokos vályog) és Szentgyörgyvölgyön, pszeudogleyes barna erdőtalajon (agyagos vályog) folytatott foszfortrágyázási tartamkísérletek talajaival végeztünk. A 10 évig (1963–73 között) intenzív, növekvő adagú feltöltő foszfortrágyázás eredményeként a talajokban három növekvő foszfor ellátottsági szint alakult ki. A talajmintavétel a 10 évig folytatott trágyázás beszüntetése után 30 év elteltével történt.
Megállapítottuk, hogy a foszfor utóhatása még 30 év elteltével is érvényesült, amely a vízoldható-, AL- és Olsen-P tartalomban is megmutatkozott. Inkubációs kísérleteink eredményei alapján kimutattuk, hogy a kedvező nedvességállapot a talajban alacsony hőmérsékleten elősegíti a kivonható P-tartalom rövid távú mobilizácóját, míg a magasabb hőmérséklet e formák immobilizációját fokozta.