A liquid chromatographic method is described for the quantification of prednisolone, benzimidazoles, and preservatives using a C 18 analytical column as stationary phase. The mobile phase was 30:70 methanol:pH 2.5 phosphate buffer at a flow rate of 1.0 mL min -1 with absorbance detection at 235 nm. The method was linear for concentrations from 40 to 10,000 ng mL -1 . Low values of coefficient of variance were obtained when samples were analyzed as replicates. Excellent recovery values were recorded in commercial products and fortified samples. International Conference of Harmonization protocols were employed to perform comprehensive method validation. The reported method has applications for pharmaceutical and serum samples.

This paper demonstrates colorimetric visible spectrophotometric quantification methods for amino acid, namely, tranexamic acid and pregabalin. Both drugs contain the amino group, and when they are reacted with 2,4-dinitrophenol and 2,4,6-trinitrophenol, they give rise to yellow colored complexes showing absorption maximum at 418 nm and 425 nm, respectively, based on the Lewis acid base reaction. Detailed optimization process and stoichiometric studies were conducted along with investigation of thermodynamic features, that is, association constant and standard free energy changes. The method was linear over the concentration range of 0.02–200 µgmL−1 with correlation coefficient of more than 0.9990 in all of the cases. Limit of detection was in range from 0.0041 to 0.0094 µgmL−1 and limit of quantification was in the range from 0.0137 to 0.0302 µgmL−1. Excellent recovery in Placebo spiked samples indicated that there is no interference from common excipients. The analytical methods under proposal were successfully applied to determine tranexamic acid and pregabalin in commercial products. t-test and F ratio were evaluated without noticeable difference between the proposed and reference methods.

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This article pertains to development and validation of an economically fast, sensitive and accurate Rp-HPLC method for quantitative analysis of HZ. A Hibar® μBondapak® C 18 column as stationary phase and acetonitrile: methanol: buffer (500:200:300) as mobile phase were used to accomplish the separation, when drawn at a flow rate of 1.0 mL/min, with 235 nm as monitoring wavelength. Linearity was established by studying the drug over the concentration range of 10-10000 ngmL -1 , correlation coefficient of r = 0.9993, drug recovery (97 to 102%) and high reproducibility in serum samples (less than 2.5% R.S.D) displayed excellent linearity, accuracy and precision. Force degradation studies of the drug under various stress conditions (acid, base, oxidation, photo and thermal) proved the stability indicating power of the method. Substantial method validation study was carried out inline with ICH guidelines and was applied successfully to quantify the amount of HZ in bulk, pharmaceutical formulations and blood serum samples. Downloaded by [Erciyes University]

A precise, accurate and sensitive liquid chromatographic method is presented for the simultaneous analysis of moxifloxacin, levofloxacin, ciprofloxacin and dexamethasone in reference drugs, ophthalmic dosage form and in physiological fluids. Separation was achieved on a C 18 analytical column with acetonitrile-phosphate buffer (35:65 v/v) as mobile phase which was pumped isocratically at a flow rate of 1.0 mL min-1 and monitored at 254 nm wavelength. The calibration curve was linear in range of 40-10 000 ng mL-1. Test results in pharmaceutical and physiological samples showed excellent drug recovery (96.5-102.3 %) with good precision (0.81-2.3 % RSD). Test results were linear to sample concentration and correlation coefficient was more than 0.9990. The small value of quantification and detection levels showed the method to be sensitive enough for use in clinical and industrial investigations of all the mentioned drugs.