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Summary

A reversed-phase high-performance liquid chromatographic method was developed for the first time to simultaneously determine salicin and eight flavonoids in leaves of Salix matsudana, that is salicin, luteolin-7-O-glucoside, myricetin, apigenin-3′-oxyethyl-7-O-glucoside, rutin, quercetin, luteolin, kaempferol and apigenin. The separation of these compounds was achieved on a reversed phase C18 column (250 × 4.6 mm, 5 μm), with linear gradient of methanol in 0.2% phosphoric acid solution with a flow rate of 1.0 mL/min with UV detection at 246 nm. The calibration curves for the determination of all analytes showed good linearity over the investigated ranges (r > 0.999). The % relative standard deviation (% RSD) values were less than 0.34%, and the recoveries were between 95.79% and 99.94%. The values of luteolin-7-O-glucoside, salicin, myricetin, apigenin-3′-oxyethyl-7-O-glucoside, rutin, quercetin, luteolin, kaempferol, and apigenin were 1.0 μg g−1, 20.0 μg g−1, 32.9 μg g−1, 2.0 μg g−1, 29.5 μg g−1, 6.0 μg g−1, 1.0 μg g−1, 3.5 μg g−1, and apigenin was not found in the sample. This developed method can be used for evaluating the quality of different plant materials.

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A sensitive and stereoselective high-performance liquid chromatography (HPLC) method based on diastereomer formation was developed and fully validated for the simultaneous determination of the two enantiomers of Baclofen. (S)-Naproxen was used to prepare three chiral derivatizing reagents (CDRs) which were used for synthesizing diastereomers of Baclofen. The diastereomers so synthesized were separated on C18 column under reversed phase conditions using a binary mixture of acetonitrile and triethylammonium phosphate, with UV detection at 220 nm. The results obtained for enantioseparation of Baclofen using the three CDRs have been compiled and compared. The conditions for derivatization and chromatographic separation have been optimized. The method was validated for linearity, repeatability, limits of detection, and limit of quantification.

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A stability-indicating liquid chromatographic (LC) method with UV detection was developed for the determination of doripenem in the marketed formulation (Doribax® 500 mg, powder for injection). A forced degradation study was conducted according to available guidelines and main references. Thermal, oxidizing, acidic and basic stress conditions were assayed to show the stability-indicating power of the method. Chromatographic separation was achieved using an isocratic elution method in a reversed-phase system using a mobile phase prepared from phosphate buffer and acetonitrile. Extensive degradation was observed under thermal, oxidative and basic treatment, and the products formed were detected without interference in the analysis of doripenem. To verify the efficiency of chromatographic run, the system suitability was studied. The theoretical plates (N = 5498.3) and tailing factor (tf = 0.951) were constant during repeated injections. The retention time of doripenem was 7.35 min and the method was validated within the concentration range 5–50 μg mL−1 (r = 0.999). Adequate results were obtained that indicate repeatability (RSD % = 1.03–1.37), inter-day precision (RSD % = 0.51) and accuracy. In comparison to spectrophotometric and microbiological methods, statistical analysis showed no significant difference between the obtained results. The proposed method was successfully applied to doripenem quantification, showing it is applicable to determine the antibiotic in the presence of degradation products and also that is a reliable method for routine analysis.

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The present study reports the dissolution method for a novel fixed dose combination (FDC) containing etodolac (ET) and propranolol hydrochloride (PH) developed utilizing USP Apparatus 1 (basket) at 100 rpm with 1000 mL of phosphate buffer (pH 6.8; 0.05 M) medium at 37°C. An isocratic reversed-phase liquid chromatographic (RPLC) method was also developed for the simultaneous determination of ET and PH on an octadecylsilica column using phosphate buffer (pH 5.5) and acetonitrile (60:40, υ/υ) as the mobile phase with ultraviolet (UV) detection at 292 nm. Validation data were obtained, which demonstrated that the dissolution methodology is accurate, precise, linear, and rugged for the combination tablets.

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The objective of the present study was to report the stability of novel antiviral drug, valganciclovir based on the information obtained from forced degradation studies. Valganciclovir was subjected to forced hydrolytic (acidic, alkaline and neutral), oxidative, photolytic and thermal stress in accordance with the ICH guideline Q1A (R2). The drug showed labiality under only acidic and photoacidic conditions while it was stable to other stress conditions. Resolution of the drug and degradation products was achieved on a Hypersil Gold C-18 column (4.6 × 250 mm, 5 μm) utilizing acetonitrile (A) and potassium dihydrogen ortho phosphate buffer (pH 5.0; 0.01M) in the ratio of 5:95 (v/v) at a flow rate of 0.6 ml/min and at the detection wavelength 252 nm. The major acidic stress degradation product was characterized by LC-MS/MS and its fragmentation pathway was proposed. Validation of the LC-DAD method was carried out in accordance with ICH guideline. The method met all required criteria and was applied for analysis of commercially available tablets.

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The gluten proteins of 15 winter wheat cultivars grown in eastern Croatia were studied for their contribution to the bread-making quality. Composition of high-molecular-weight glutenin subunits (HMW-GS) was analyzed by SDS-PAGE, while the quantity of gluten proteins was determined by combined extraction/RP-HPLC procedure. The results of the linear correlation analysis carried out on the particular gluten proteins and technological properties showed that the amount of total gluten content highly correlates with protein content. Among gluten proteins, the glutenins showed higher correlation with protein content, with pronounced influence of HMW-GS, than gliadins. Wet gluten content was significantly correlated to total gliadin quantity. Gluten index as gluten quality parameter was positively influenced by total glutenins and low-molecular-weight glutenin subunits (LMW-GS), and negatively, by the ratios of gliadin to glutenin (Gli/Glu), whereas the amount of gliadins was not important. Dough development time was strongly correlated with total gluten content, total glutenins and the Gli/Glu ratio. Dough mixing resistance was strongly affected by total glutenin content with pronounced influence of HMW-GS. Degree of dough softening is mainly negative influenced by total glutenins and ratio of Gli/Glu. Farinograph quality number as flour quality index was highly positively correlated with total glutenins, with emphasized influence of HMW-GS. The Gli/Glu ratio had the highest influence on dough maximum resistance. Dough extensibility showed moderate correlation with total gliadins. The results of the linear correlation indicated that loaves volumes were significantly influenced by total gluten proteins, HMW-GS and LMW-GS.

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Acta Chromatographica
Authors: Mohammad Al Bratty, Neelaveni Thangavel, Ramalingam Peraman, Vinod Kumar, Padmanabha Reddy, Krishna Veni Nagappan, and Hassan Al Hazmi

identification of process impurities [ 18 ] and degradation products [ 19 ] for PTZ by reversed-phase HPLC (RP-HPLC) methods. Besides, several analytical studies are available for PTZ in the literature, but those methods are not realistic and logically

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Modifiedß-casein forms were prepared with acid/alkaline phosphatase. The choice between acid and alkaline phosphatases was critical for the physico-chemical properties ofß-casein. Removal of phosphoryl groups fromß-casein via alkaline phosphatase increased the retention time measured using RP-HPLC and did not change the second-derivative UV spectra. Moreover, the pI value shifted to neutral pH and the solubility decreased, especially at the alkaline pH range.ß-Casein modified enzymatically via alkaline phosphatase formed a foam with volume and stability similar to that formed with intact one. In turn, a dramatic decrease in foam stability was found forß-casein modified via acid phosphatase. Chromatographic, spectral and electrophoretic results suggest proteolytic acivity of acid phosphatase preparation.

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Summary

A simple, reversed-phase HPLC method has been developed for rapid, simultaneous quantification of phenylephrine hydrochloride, guaiphenesin, ambroxol hydrochloride, and salbutamol (as salbutamol sulphate) in a commercial cough-cold liquid formulation. The compounds were separated on a 250 mm × 4.6 mm C8 column with a gradient prepared from pH 3.0 phosphate buffer and 1:1 methanol-acetonitrile as mobile phase at a flow rate of 1.0 mL min−1. Elution of the analytes was achieved in less than 15 min. Detection was by UV absorbance at 273 nm for phenylephrine hydrochloride and guaiphenesin and 225 nm for ambroxol hydrochloride and salbutamol. Percentage recovery and RSD were, respectively, 100.09% and 0.22% for phenylephrine hydrochloride, 100.43% and 0.50% for guaiphenesin, 100.91% and 0.70% for ambroxol hydrochloride, and 100.54% and 0.55% for salbutamol. The components of the syrup formulation were quantified on the basis of the peak areas obtained from freshly prepared standard solutions. The method was validated in accordance with ICH guidelines.

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