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Summary

Two simple and accurate reversed-phase high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) methods for simultaneous determination of atorvastatin calcium and losartan potassium in tablet dosage forms have been established and validated. The HPLC separation was achieved on a Phenomenex Luna C18 column (250 mm, 4.6 mm i.d., 5 μm) with 0.05 M potassium dihydrogen phosphate buffer (pH 5.4)-acetonitrile 45:55 (%, v/v) as isocratic mobile phase at a flow rate of 1 mL min−1. The retention times were approximately 7.56 and 3.73 min for atorvastatin calcium and losartan potassium, respectively. Quantification was achieved at 238 nm with a photodiode-array (PDA) detector over the concentration range 0.5–5 μg mL−1, for each compound, with mean recoveries of 100.67 ± 0.58 and 100.51 ± 0.63% for atorvastatin calcium and losartan potassium, respectively. The HPTLC separation was achieved on silica gel 60 F254 HPTLC plates with methanol-carbon tetrachloride-ethyl acetate-glacial acetic acid 8:63.6:28:0.4 (v/v) as mobile phase. The retardation factors (R F) were approximately 0.45 and 0.30 for atorvastatin calcium and losartan potassium, respectively. Quantification was achieved by ultraviolet (UV) detection at 238 nm over the concentration range of 50–500 ng band−1 for each, with mean recoveries of 100.59 ± 0.47 and 100.48 ± 0.81% for atorvastatin calcium and losartan potassium, respectively. Both methods were validated, and the results were compared statistically by use of a paired t-test. The methods were found to be simple, specific, accurate, precise, and robust, and were successfully used for analysis of the drugs in tablet dosage forms without interference from common excipients.

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A simple, sensitive, and accurate liquid chromatographic method with photodiode array detector was developed for the determination of andrographolide, phyllanthin, and hypophyllanthin. The separation was carried out on a reverse-phase 250 mm × 4.6 mm, 5μ symmetry C8 column (Waters). The gradient was prepared from 0.1% orthophosphoric acid (solvent A) and (1:1) acetonitrile:methanol (solvent B) as mobile phase delivered at a flow rate of 1 mL min−1. A linear behavior was observed between observed peak area response, and concentration of analytes was investigated, with good correlation coefficient. The method established was successfully applied to quantify andrographolide, phyllanthin, and hypophyllanthin from the herbal hepatoprotective formulation.

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A simple and selective liquid chromatographic method was developed for the simultaneous determination of tenofovir disoproxil fumarate (TEN) and emtricitabine (EMT) in combined tablets. The method is based on separation of TEN and EMT on a Zorbax SB-C8 column, 5 μm, 4.6 × 250 mm, with a mobile phase consisting of 50 mM disodium hydrogen phosphate-acetonitrile (50:50, v/v). The mobile phase contains 0.1% triethylamine (TEA) and was adjusted to pH 6.0. Quantification of the analytes is achieved with diode array — ultraviolet detector (DAD-UV) at 260 and 280 nm for TEN and EMT, respectively, based on peak area. Different variables affecting the method were carefully investigated and optimized. Reliability and analytical performance of the proposed method, including linearity, range, precision, accuracy, and detection and quantitation limits, were statistically validated. The high-performance liquid chromatography (HPLC) method was successfully applied for determination of each drug in their binary tablets.

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Vicia faba, also known as “bakla” in Turkey, is a species of Fabaceae family that is widely grown in Africa and Asia. It is rich in levodopa, a medicinal substance used to treat Parkinson's disease. Levodopa produced by chemical synthesis is expensive and causes various side effects. Therefore, it is recommended to use natural levodopa sources to prevent possible side effects. A Central Composite Design technique has been used in this study to optimize levodopa extraction from Vicia faba. First, a single factor analysis examined 3 variables such as extraction temperature, extraction time, and concentration of acetic acid. The purpose of this study was to assess the effects of variables chosen on levodopa's extraction performance. By using variance and regression analyses, a second-order regression equation was determined as a predicted model. The value of R 2 is 0.9882, which shows that the equation fits well. The best conditions are as follows: a temperature of 59.85 °C, an extraction time of 18.74 min, and an acetic acid content of 0.28%. Under optimum conditions, the maximum levodopa yield calculated from the predicted module was 4.53%. Extraction efficiency was determined as 4.54% experimentally under optimum conditions. A good relationship has been found between the experimental result and the predicted value.

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Under artificial Fusarium infection the total glutenin content determined by chromatographic (RP-HPLC) method was significantly reduced in comparison to gliadins which were increased. Among protein types, α-GLI and HMW-GS were the highest affected. Artificial Fusarium infection significantly increased GLI/GLU ratio when compared with the natural infected samples. Artificial Fusarium infection dramatically decreased the dough mixing tolerance and had a considerable negative effect on dough energy, maximum resistance, and resistance/extensibility ratio. Disturbed GLI/GLU ratio and an increased amount of mycotoxin DON under artificial Fusarium infection showed a strong negative impact on affected functional properties of dough and bread. Total and γ-GLI as well as GLI/GLU ratio were significantly positively affected by mycotoxin DON in contrast to total GLU, HMW-GS and LMW-GS which were negatively affected. Results indicated that the stability of baking quality parameters of cultivars more tolerance to the Fusarium infection can be well define by lower accumulation of mycotoxin DON.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Erzsébet Háznagy-Radnai, Klára Pintye-Hódi, Szilvia Czigle, Tamás Martinek, Gábor Janicsák, Imre Máthé, and István Erős

We have isolated five iridoids (harpagide, acetylharpagide, harpagoside, ajugoside, and aucubin) from St. recta L. by a combination of chromatographic methods-NP-TLC, RP-HPLC, and TLC-densitometry. The isolated iridoids were identified on the basis of their physical and spectroscopic properties. Basic information about their structures was obtained from their NMR spectra. X-ray fluorescence spectroscopy can be used for direct determination of inorganic elements in the leaves, stems, and inflorescences of Stachys recta L. We identified K, Ca, Mo, Fe, Co, Ir, Ga, Tl, and S.

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The hordein proteins of ten barley ( Hordeum vulgare L.) cultivars grown in region of eastern Croatia were studied for their contribution to the malting quality, particularly relating hordein influence on malt extract yield. The analysis of hordein proteins was carried out by reversed-phase high-performance liquid chromatography (RP-HPLC). The micromalting of investigated barley cultivars and malt analyses were done according to the EBC official methods. The quantitative analysis of hordein proteins has showed that B-hordein was major component, followed by C- and D-hordeins. Among investigated cultivars the malt extract yield varied from 76.8% (cv. Angora) to 82.6% (cv. Scarlett). Spring barleys had on the average higher malt extract yield in contrast to winter barleys. The significant negative correlation between the total hordein content and malt extract yield was found. Among hordein fractions the B-hordein and D-hordein significantly contributed to lower malt extract yield. RP-HPLC analysis of malt hordeins revealed that the amount of hordein degraded during malting significantly correlated with Kolbach index.

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Cereal Research Communications
Authors: D. Horvat, N. Ðukić, D. Magdić, J. Mastilović, G. Šimić, A. Torbica, and D. Živančev

Glutenin polymers composed of HMW and LMW subunits are important contributors to the wheat end-use properties. Twenty-six winter wheat cultivars differing in bread processing quality were collected at the experimental fields of the Agricultural Institute Osijek, Croatia and Institute of the Field and Vegetable Crops Novi Sad, Serbia, in 2008/2009 season. The HMW glutenins composition and glutenin proteins content were determined by SDS-PAGE and RP-HPLC, respectively, with aim to determine the relationship between glutenin protein fractions and wheat quality properties. Significant differences were found between Croatian and Serbian cultivars in several quality attributes (GI, WA, DDT, DS and R/EXT) as well as in the content of total glutenins and LMW glutenins and GLI/GLU ratio. The dominant HMW subunits in analyzed cultivars were 2*, 7 + 9/7 + 8 and 5 + 10. Principal component analysis (PCA) confirmed the presence of association between HMW glutenins composition and GI, dough E, R and R/EXT, while the glutenins quantitative data showed pronounced relation with P, DDT, DS, E, R and R/EXT. GLI/GLU ratio had the opposite effect on these parameters.

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A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous determination of doxazosin mesylate (DOX) and finasteride (FIN) in bulk powders and pharmaceutical formulations. The compounds were separated on a Pinnacle II C18 column (250 × 4.6 mm i.d.; particle size, 5 μm) with an isocratic mobile phase at a flow rate of 1.0 mL min−1. The mobile phase was a mixture of 25 mM ammonium acetate and acetonitrile in the ratio of 50:50 %v/v. The pH of the buffer was adjusted to 4.0 ± 0.05 with glacial acetic acid. The detection was performed at 230 nm. The total chromatographic analysis time per sample was 15 min with DOX and FIN eluting at 3.9 and 7.2 min, respectively. The accuracy, precision, specificity, linearity, and sensitivity of the method were validated according to the International Conference on Harmonization (ICH) guidelines. The calibration plots were linear (r 2 > 0.999) over the concentration range 24.25–291.0 μg mL−1 and 122.5–1470.0 μg mL−1 for DOX and FIN, respectively. The method was used for the simultaneous determination of DOX and FIN in capsules.

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Summary

In this chapter, an isocratic reverse phase HPLC determination of mimosine was developed and validated in an anti-psoriatic topically applied formulation “Lajjalu”. The chromatography was performed on a C18 column with water-orthophosphoric acid (98.8:0.2, υ/υ) as a mobile phase with a pH of 3.0 at a flow rate of 1.0 mL min−1. Detection was performed at 284 nm, and a sharp peak was obtained for mimosine at a retention time of 2.62 ± 0.01 min. Linear regression analysis data for the calibration plot showed a good linear relationship between response curve and concentration in the range of 0.050–5000 ng mL−1 and the regression coefficient was 0.9998 with the linear regression equation y = 4766.8x−17726. The detection (LOD) and quantification (LOQ) limits were 10.3 and 35.6 ng mL−1, respectively. The wide linearity range, sensitivity, accuracy, short retention time, and simple mobile phase imply the method is suitable for routine quantification of mimosine with high precision and accuracy.

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