A simple, rapid and robust LC method was developed and validated for the enantiomeric separation of metolazone. The enantiomers of metolazone were resolved on a Chiralpak AD-H (amylose based stationary phase) column using a mobile phase consisting of Hexane: 2-propanol: Methanol: Acetic acid (80:10:10:0.2, v/v) at a flow rate of 1.0 mLmin-1. The resolution between the enantiomers was found to be not less than 3.0 in optimized method. The presence of acetic acid in the mobile phase played an important role, in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was extensively validated and proved to be robust. The calibration curve for enantiomers showed excellent linearity over the concentration range of 5 μgmL-1 to 50 μgmL-1. The limit of detection and limit of quantification for enantiomers were 0.05 and 0.16 μgmL-1, respectively. The proposed method was found to be suitable and accurate for quantitative determination of enantiomers in bulk drug substance.

Um método de HPLC quiral em fase normal, simples, rápido, isocrático, foi desenvolvido e validado para a separação enantiomérica de repaglinida, ácido (S)-(+)-2-etóxi-4-N [1-(2-piperidinofenil)-3-metil-1-butil] aminocarbonilmetil] benzóico, uma substância antidiabética. Os enantiômeros de repaglinida foram resolvidos em uma coluna Chiralpak IA (fase estacionária a base de amilose imobilisada) usando uma fase móvel consistindo de n-hexano:etanol:ácido trifluoroacético (80:20:20, v/v/v) a uma vazão de 1,0 mL min-1. A resolução encontrada entre os enantiômeros foi maior do que 2 no método otimizado. O método desenvolvido foi extensivamente validado e mostrou-se robusto, enantiosseletivo, exato, preciso e adequado para determinação quantitativa de (R)-enantiômero na substância a granel e no produto formulado.

A simple, rapid, isocratic, normal phase chiral HPLC method was developed and validated for the enantiomeric separation of repaglinide, (S)-(+)-2-ethoxy-4-N [1-(2-piperidinophenyl)-3-methyl-1-butyl] aminocarbonylmethyl] benzoic acid, an antidiabetic drug substance. The enantiomers of repaglinide were resolved on a Chiralpak IA (immobilized amylose based stationary phase) column using a mobile phase consisting of n-hexane:ethanol:trifluoroacetic acid (80:20:0.2, v/v/v) at a flow rate of 1.0 mL min-1. The resolution between both enantiomers was greater than 2 in the optimized method. The developed method was extensively validated and proved to be robust, enantioselective, accurate, precise, and suitable for quantitative determination of (R)-enantiomer in bulk drug substance and product.

A simple, rapid, and precise method is developed for the quantitative simultaneous estimation of telmisartan and hydrochlorothiazide in combined pharmaceutical dosage form. A chromatographic separation of the two drugs was achieved with an ACE 5 C18 (250 x 4.6 mm) analytical column using buffer-acetonitrile (55:45 v/v). The buffer used in mobile phase contains 0.1M sodium perchlorate monohydrate in double distilled water pH adjusted 3.0 with trifluoroacetic acid. The instrumental settings are flow rate of 1.5 ml min-1, column temperature at 30ºC, and detector wavelength of 215 nm using a photodiode array detector. The resolution between hydrochlorothiazide and telmisartan founds to be more than 5. Theoretical plates for hydrochlorothiazide and telmisartan were 13022 and 6629 respectively. Tailing factor for hydrochlorothiazide and telmisartan was 0.94 and 0.98 respectively. Telmisartan, hydrochlorothiazide and their combination drug products stressed samples were analysed by the proposed method. The described method shows excellent linearity over a range of 70 to 130% of target analyte concentration. The correlation coefficient for telmisartan and hydrochlorothiazide are 0.9999. The relative standard deviation for six measurements in two sets of each drug in tablets is always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination and stability study of telmisartan and hydrochlorothiazide in pharmaceutical preparations.

A simple, rapid and robust LC method was developed and validated for the enantiomeric separation of dexrabeprazole in bulk drug and formulation. The enantiomers of dexrabeprazole were resolved on a Chiralpak AD-RH (amylose based stationary phase) column using a mobile phase consisting of water: acetonitrile (50:50, v/v) at a flow rate of 0.5 ml min¹. The resolution between the enantiomers was found to be more than 1.5 in optimized method. The developed method was extensively validated and proved to be robust. The calibration curve for (S)-enantiomer showed excellent linearity over the concentration range of 0.05 µg ml¹ (LOQ) to 1 µg ml¹. The limit of detection and limit of quantification for (S)-enantiomer were 0.015 µg ml¹ and 0.05 µg ml¹, respectively. The percentage recovery of the (S)-enantiomer ranged between 97 to 101 % in bulk drug samples of dexrabeprazole. The proposed method was found to be suitable and accurate for quantitative determination of (S)-enantiomer in bulk drug substance.