A new ultra-performance liquid chromatography (UPLC) with photodiode array was proposed for the quantitation of Brimonidine Tartrate (BRI) and Timolol Maleate (TIM) in eye drop using experimental design and optimization methodology. A 3 full factorial design was applied to uncover the effects of the selected factors and their interactions on the chromatographic response function for the optimization of experimental conditions in the development of a new UPLC method. As a result, the optimal chromatographic conditions giving a better separation and short analysis time were found to be 49.2°C for column temperature; 0.38 mL/min for flow rate and 56.7 % (v/v) for 0.1 M CHCOOH used in mobile phase. The elution of BRI and TIM was reported as 0.508 and 0.652 min within a short runtime of 1.5 min, respectively. Calibration graphs for BRI and TIM were obtained by the regression of the concentration on the peak area, which was detected at 246 and 298 nm, respectively. The method validation was performed by the analysis of the synthetic mixtures, intra-day and inter-day samples and standard addition samples. This study shows that the optimized and validated UPLC method is very promising and available for the quantification of BRI and TIM in an eye drop formulation.

No abstract

A new application of continuous wavelet transform (CWT) to overlapping peaks in a chromatogram was developed for the quantitative analysis of amiloride hydrochloride (AML) and hydrochlorothiazide (HCT) in tablets. Chromatographic analysis was done by using an ACQUITY ultra-performance LC (UPLC) BEH C18 column (50 x 2.1 mm id, 1.7 pm particle size) and a mobile phase consisting of methanol-0.1 M acetic acid (21 + 79, v/v) at a constant flow rate of 0.3 mL/min with diode array detection at 274 nm. The overlapping chromatographic peaks of the calibration set consisting of AML and HCT mixtures were recorded rapidly by using an ACQUITY UPLC H-Class system. The overlapping UPLC data vectors of AML and HCT drugs and their samples were processed by CWT signal processing methods. The calibration graphs for AML and HCT were computed from the relationship between concentration and areas of chromatographic CWT peaks. The applicability and validity of the improved UPLC-CWT approaches were confirmed by recovery studies and the standard addition technique. The proposed UPLC-CWT methods were applied to the determination of AML and HCT in tablets. The experimental results indicated that the suggested UPLC-CWT signal processing provides accurate and precise results for industrial QC and quantitative evaluation of AML-HCT tablets.

Two-way and three-way calibration models were applied to ultra high performance liquid chromatography with photodiode array data with coeluted peaks in the same wavelength and time regions for the simultaneous quantitation of ciprofloxacin and ornidazole in tablets. The chromatographic data cube (tensor) was obtained by recording chromatographic spectra of the standard and sample solutions containing ciprofloxacin and ornidazole with sulfadiazine as an internal standard as a function of time and wavelength. Parallel factor analysis and trilinear partial least squares were used as three-way calibrations for the decomposition of the tensor, whereas three-way unfolded partial least squares was applied as a two-way calibration to the unfolded dataset obtained from the data array of ultra high performance liquid chromatography with photodiode array detection. The validity and ability of two-way and three-way analysis methods were tested by analyzing validation samples: synthetic mixture, interday and intraday samples, and standard addition samples. Results obtained from two-way and three-way calibrations were compared to those provided by traditional ultra high performance liquid chromatography. The proposed methods, parallel factor analysis, trilinear partial least squares, unfolded partial least squares, and traditional ultra high performance liquid chromatography were successfully applied to the quantitative estimation of the solid dosage form containing ciprofloxacin and ornidazole.

No abstract