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A rapid, sensitive and stability indicating high performance liquid chromatographic method was developed and validated for the analysis of dehydroepiandrosterone (DHEA) in pharmaceutical tablet formulation. The analysis was done on a Supelcosil C18 column (25 cm × 4.6 mm i.d., 5 µm). The mobile phase consisted of methanol:sodium acetate buffer solution (5 g/L):acetic acid (500 mL/L), 57:42:1, v/v/v, adjusted to pH 5 at a flow rate of 1 mL/min. Detection was carried out at a wavelength of 258 nm. The polynomial regression data for the calibration curve showed good linear relationship in the concentration range of 0.2–1 mg/mL with r = 0.9996. The method was validated for precision, accuracy and recovery. The limit of detection was found to be 50 ng/µL. The method was applied for the analysis of DHEA in its pharmaceutical tablet formulation. The effects of different buffers and alcohols on the retention of DHEA were studied and the role of acetic acid as an organic phase modifier was also investigated. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A sensitive enantioselective high-performance liquid chromatography (HPLC) method was developed and validated to determine S-(+)- and R-(-)-arotinolol in human plasma. Baseline resolution was achieved by using teicoplanin macrocyclic antibiotic chiral stationary phase (CSP) known as Chirobiotic T with a polar organic mobile phase consisting of methanol:glacial acetic acid:triethylamine, 100:0.1:0.1, (v/v/v) at a flow rate of 0.8 mL/min and UV detection set at 317 nm. Human plasma was spiked with stock solution of arotinolol enantiomers and labetalol as the internal standard. The assay involved the use of liquid–liquid extraction procedure with ethyl ether under alkaline condition for human plasma sample prior to HPLC analysis. Recoveries for S-(+)- and R-(-)-arotinolol enantiomers were in the range 93–103% at 200–1400 ng/mL level. Intra-day and inter-day precision calculated as %RSD was in the ranges 1.3–3.4 and 1.9–4.5% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percentage error were in the ranges 1.2–3.5 and 1.5–6.2% for both enantiomers, respectively. Linear calibration curves in the concentration range 100–1500 ng/mL for each enantiomer showed a correlation coefficient (r) of 0.9998. The limit of quantitation (LOQ) and limit of detection (LOD) for each enantiomer in human plasma were 100 and 50 ng/mL (S/N = 3), respectively. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Impregnated silica TLC plates with L-(−)-serine and L-(−)-threonine and a mixture of L-(−)-serine and L-(−)-threonine (1:1) as chiral selectors were prepared to use as chiral stationary phases (CSPs) in thin layer chromatography. The resolution of the enantiomers of 2-arylpropionic drugs, including ibuprofen, ibuproxam, ketoprofen, pranoprofen, benoxaprofen, flurbiprofen and tiaprofenic acid was investigated on these CSPs. A mobile phase system of acetonitrile–methanol–water (16:4:0.5, v/v/v) was used. The spots were detected with iodine vapours and the detection limits were found to range between 0.25 and 0.5 µg/mL for all racemic compounds investigated. The effect of temperature, pH and concentration of the impregnating chiral selectors on resolution has been studied. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]