A new and enantioselective liquid chromatographic method was developed for estimation of S-Linagliptin in Linagliptin (LINA) drug substances. The desired enantiomeric separation was achieved on Chiralpak AD-H (250 * 4.6 mm * 5 µm) column with the mobile phase composition of ethanol, methanol and diethylamine in a ratio of 90:10:0.1 (v/v/v) with flow rate of 0.5 mL•min −1 and column oven temperature 30˚C and the eluted compounds were monitored at 225 nm. In the proposed chiral method, USP resolutions between both the enantiomers were more than 5.0. Limit of detection and Limit of quantitation of S-LINA was found to be 0.03 µg•mL −1 and 0.10 µg•mL −1 respectively. Linearity study was conducted from LOQ to 150% and correlation coefficient found to be 0.9997. Accuracy was within the range of 98.6% to 101.5%. To prove selectivity power of the method specificity study was conducted by subjecting drug substance to acid, base, hydrolysis, oxidation and photolysis and ensured the peak purity of analyte in degraded samples. Moreover, the method has been fully validated as per ICH guidelines. The proposed method is precise, accurate, linear, rugged, robust and suitable for accurate quantification of S-LINA in LINA drug substance.

A quick and simple isocratic stability indicating method has been developed for the quantification of Ixabepilone in active pharmaceutical ingredient and injection dose formulation using reversed phase‐high‐performance liquid chromatography. Based on the response of Ixabepilone and impurities, the method was developed on a Symmetry C18 (150 × 4.6) mm, 5‐micron (Waters) column. An isocratic mobile phase consisted of pH 4.7 acetate buffer (10 mM) and acetonitrile in the composition of 60:40 v/v at 1.0 ml/min flow rate with a run time of 15 min, and Ixabepilone was eluted at about retention time of 5.1 min. The developed method is validated to meet International Conference on Harmonization standards. Linearity of Ixabepilone was established for the concentration range 0.050 to 0.15 mg/ml (r2 > 0.999) with respect to working concentration 0.10 mg/ml. Recovery was established from 50% (0.050 mg/ml) to 150% (0.15 mg/ml) of the target concertation (0.10 mg/ml). Precision and Intermediate precision met the acceptance criteria as per International Conference on Harmonization Q2(R1). It was proved that the stability indicating nature for quantifying Ixabepilone in Ixabepilone active pharmaceutical ingredient and drug product. As a result, the assay of Ixabepilone can be analyzed using this method for pharmaceutical development and quality control.

The aim of this study was to develop a simple and derivatization free method for the Quantification of S-Epichlorohydrin in R-Epichlorohydrin by using a gas chromatography coupled with flame ionization detector (FID). Enantiopure epichlorohydrin was a valuable epoxide key starting material for preparing optically active Rivaroxaban. The enantiomeric separations of S-Epichlorohydrin and R-Epichlorohydrin were achieved on Gamaa-Dex-225 (30 meters × 0.25 mm I.D, 0.25 µm) column with a total run time of 30 min. Nitrogen was used as a carrier gas with constant pressure 25.0 psi. The critical experimental parameters such as, column selection, flow rate, injection volume and diluent were studied and optimized. Excellent correlation coeffient between peak responses and concentrations was >0.9998. The recoveries of S-Epichlorohydrin spiked in R-Epichlorohydrin were in the range from 98.2% to 102.8%. Limit of quantitation for S-Epichlorohydrin was sufficiently lower than limits specified by ICH. The method has validated as per International Conference on Harmonization (ICH) guidelines. A precise, accurate, linear and robust Gas Chromatography method was developed for the quantification of S-Epichlorohydrin in R-Epichlorohydrin for Rivaroxaban.

The aim of this study is to develop a stability‐indicating, reversed‐phase HPLC method for the quantification of assay and organic impurities (process and degradation) of doxycycline hyclate in a doxycycline injectable formulation. Both the active and dosage forms are officially present in the USP monograph, and assay and impurity methods are provided by separate UPLC techniques, which are highly sensitive to the flow rate and temperature, considering the quality control requirements and user‐friendliness. A simple stability‐indicating HPLC method with a shorter run time was developed for the simultaneous quantification of assay and impurity. The method was developed using HPLC with a gradient program and a reversed‐phase Waters XBridge BEH C8 column (150 × 4.6 mm, 3.5 μm i.d.). Mobile phase A consisted of phosphate buffer (pH 8.5, 25 mM potassium phosphate, 2 mM ethylenediaminetetraacetic acid, and 0.5 ml of triethylamine). Mobile phase B consisted of methanol with a flow rate of 1.7 ml/min, a column temperature of 55°C, a UV wavelength of 270 nm, and an injection volume of 25 μl. Modern research represents a concomitant method for quantifying assay and organic impurities of doxycycline hyclate (active form) and doxycycline for injection (dosage form). The assay and impurity method were validated per United States Pharmacopeia (USP) 1225 and International Conference on Harmonization (ICH) guidelines. The retention time of doxycycline and degradation impurity, 4‐epidoxycycline, was about 9.8 and 6.4 min, respectively. The linearity range of doxycycline and 4‐epidoxycycline was 0.5–150 and 0.5–18 μg/ml, respectively. The percentage of recovery of doxycycline and 4‐epidoxycycline was 98.7–100.6% and 88.0–112.0%. Validation of the analytical method demonstrated that the method is suitable, specific, linear, accurate, precise, rugged, and stability indicating for estimating the assay, known and degraded impurities of doxycycline, and doxycycline for injection.