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- Author or Editor: S. Sultana x
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Abstract
A simple, sensitive, and rapid RP-HPLC method for analysis of enalapril in the presence of H2-receptor antagonists has been developed and validated. Enalapril maleate was separated from H2-receptor antagonists by use of a 250 mm × 4.6 mm, 5-µm particle, C18 column with 86:14 (υ/υ) methanol-water, pH adjusted to 3.5, as mobile phase, at a flow rate of 1.5 mL min−1. UV detection was performed at 227 nm. The retention times of enalapril maleate, ranitidine, cimetidine, and famotidine were 3, 5, 7, and 7.5 min, respectively. The detection limit for enalapril was 10 ng mL−1 and the calibration plot was linear in the range 2.5–50 µg mL−1. In-vitro interaction of enalapril with the commonly administered H2-receptor antagonists cimetidine, ranitidine, and famotidine in simulated gastric juice at different pH and 37°C was also studied by use of this method. These studies clearly indicated that most of these H2-receptor antagonists bind to enalapril causing drastic changes in the availability of the drug. The HPLC method is accurate, selective, sensitive, and reproducible.
Summary
A simple, selective, precise, accurate, and cost-effective thin-layer chromatographic (TLC) method for analysis of psoralen in different brands of babchi (Psoralea corylifolia) oil has been developed and validated. Aluminium TLC plates precoated with silica gel 60F254 were used as the stationary phase and n-hexane-acetone-formic acid 2:1:0.025 (v/v) as mobile phase. A compact, resolved psoralen peak (R F value 0.32 ± 0.02) was observed by densitometric analysis in absorbance mode at 250 nm. Calibration data revealed a good linear relationship (r 2 = 0.9956) between peak area and concentration in the range 20–200 ng per spot. Mean ± SD values of slope and intercept were 11.35 ± 0.36 and 14.64 ± 0.31, respectively. Statistical analysis proved the method to be a repeatable, selective, and accurate means of estimation of psoralen in different brands of babchi oil.
Summary
A simple, rapid, and sensitive high-performance liquid chromatography method was developed and validated for the simultaneous determination and quantification of fusidic acid and steroids (prednisone, betamethasone valerate, hydrocortisone acetate, and dexamethasone sodium) from bulk drugs and human plasma. A RP-HPLC, operated at ambient temperature, was equipped with a UV detector for monitoring the effluents at 235 nm. The mobile phase consisted of methanol, acetonitrile, and 0.05 M phosphoric acid (10:60:30, v/v/v), and separation was achieved on a Medeterrane, C18 (5 μm, 12.5 × 0.46 mm) column at a flow rate of 1.7 mL min−1. Calibration curves were linear over concentration range 0.625–10 μg mL−1 with correlation coefficient (r 2) greater than 0.9999. The coefficient of variation (CV) and relative error (RE) for intra- and interassay were <2% and <1%, respectively. Interference of other already administered common medicaments, such as aspirin, paracetamol, caffeine, nicotine, and other plasma components, were not found.
An alkaline thermotolerant lipase of Bacillus coagulans BTS1 was successively purified by ammonium sulfate precipitation and DEAE anion exchange chromatography. The purified lipase immobilized in alginate beads showed an optimal activity at pH 7.5 and 55ºC. A pH of 5.0 or 10.0 completely quenched the activity of immobilized lipase. The alginate-bound lipase retained its activity following exposure to most of the organic solvents including amines, alkanes and alcohols. Chloride salt of Al3+, Co2+, Mg2+ and NH4+ modulated the lipase activity of alginate-immobilized enzyme. The alginate entrapped lipase showed a preferentially high activity towards p-nitrophenyl palmitate (C: 16) and activity of matrix increased following exposure to SDS. Moreover, the immobilized lipase retained more than 50% of its activity after 3rd cycle of reuse.
Selection on the basis of grain yield per se for improved performance under excessive moisture stress has often been misleading and considered inefficient. We assessed the importance of secondary traits of adaptive value under waterlogging stress. During the 2000–2004 summer-rainy seasons twelve trials were conducted and a total of 436 tropical/subtropical inbred lines (S 4 –S n ) were evaluated under excessive soil moisture stress. Excessive moisture treatment was applied at V 6–7 growth stage by flooding the experimental plots continuously for seven days. Different phenological and physiological parameters were recorded before, during and either immediately or 1–2 weeks after exposure to stress. Excessive moisture conditions significantly affected all the morphological and physiological traits studied. However, there was significant genetic variability for various traits, especially for root porosity and brace root development that were induced under excessive moisture. Across the trials, significant genetic correlations (p<0.01) was obtained between grain yield and different secondary traits, including ears per plant, root porosity, brace root fresh weight, number of nodes with brace roots and anthesis silking interval. Broad-sense heritability decreased under excessive moisture stress conditions for most of the traits; however, it increased significantly for root porosity, nodal root development and ears per plant. Our findings suggest that consideration of these second-ary traits during selection of maize germplasm for excessive moisture tolerance can improve selection efficiency and genetic gains.
Summary
Formaldehyde in aquatic products was determined by micellar electrokinetic capillary chromatography (MEKC) after derivatization with 2,4-dinitrophenylhydrazine. Separation was carried out at 25 °C and 25 kV, using a fused silica capillary (75 µ internal diameter; 50.5 cm effective length) and an ultraviolet detector set at 360 nm. The optimal background electrolyte was 20 mM sodium tetraborate and 20 mM sodium dodecyl sulfate at pH 9.0 with 3 s hydrodynamic injection at 30 mbar. Electrophoretic analysis took approximately 6.5 min. The correlation coefficient of the calibration curve was 0.999 over the concentration range 2.0–100.0 mg L−1, and the LOD and LOQ values were 0.57 and 1.89 µg mL−1, respectively. The recoveries were from 83.7% to 97.2% with steam distillation as the sample pretreatment method.
Abstract
The solvent extraction behavior of radioioine and astatine has been investigated under various conditions in order to compare the extraction behavior of astatine with radioiodine at tracer concentration. In this study, basic tracer solutions of astatine and radioiodine were extracted into the CS2 solution under various conditions. Astatine existed as a pure species in the tracer solution and formed cationic compound in the acidic solution which was also extracted into the organic solvent instantaneously. On the other hand, radioiodine existed as a complex in the tracer solution and was partly extracted into the organic solvent at tracer concentration. The observed different extraction behavior of astatine and radioiodine were consistently explained by the respective proposed extraction reaction schemes.
Pollen morphology of 16 species belonging to 8 different families; Apocynaceae, Brassicaceae, Capparaceae, Euphorbiaceae, Fabaceae, Poaceae, Solanaceae and Zygophyllaceae were analysed from Khyber Pakhtunkhwa with the help of microscopic techniques. Both qualitative and quantitative features of pollen were examined including polar and equatorial diameter, colpus length and width, exine sculpturing, pores number, pollen shape, number of sterile and fertile pollen using Leica microscope (D1000) fitted with camera Meiji Infinity 1 and examined statistically by software IBM SPSS Statistics 20. Pollen observed were small to large with suboblate, oblate-spheroidal, prolate-spheroidal and subprolate shape. Exine ornamentations were reticulate and psilate type in all the studied plants. Colpi and pores of the selected plants observed are tricolporate, tricolpate and monoporate. The present study showed that both spring and autumn seasons are the prominent seasons for honey production and beekeeping industries in Khyber Pakhtunkhwa. Brassica camp-estris is the most visited species by honeybees in the study area. Melliferous plants gave knowledge about botanical origin of honey and geographical origin of honeybees. The current study identified numerous bee forage plants which may help to raise the concept of cultivation of melliferous herbaceous plants by the local people, to be used for honey production. The identification of these potential sources may help the beekeepers to increase the honey production and increase in agricultural yields through pollinations.
Summary
A new, simple, selective, precise, robust and stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been established for analysis of terbinafine hydrochloride (TH) in the bulk drug and in pharmaceutical formulations. Separation was achieved on aluminium plates precoated with silica gel 60F254, with toluene-ethyl acetate-formic acid 4.5:5.5:0.1 (v/v) as mobile phase. Densitometric analysis was performed at 284 nm. Compact bands of TH were obtained at R F 0.31 ± 0.02. Linearity (r 2 = 0.9985), limit of quantification (35 ng per band), recovery (97.6−101.6%), and precision (≤2.19) were satisfactory. The method was applicable for routine analysis and accelerated stability testing of TH in pharmaceutical drug-delivery systems. Because the method can effectively separate the drug from its degradation products, it can be used as a stability-indicating method.
