A novel voltammetry offline coupled MALDI/TOF MS characterization of electrochemical reaction products and the voltammetric determination of febuxostat in human plasma.

A simple offline coupling voltammetry-MALDI/TOF MS procedure is presented for studying electrochemical reactions. It was utilized for the characterization of the electro-reduction products of febuxostat in methanolic acetate buffer (0.1 M, pH 5).

Simultaneous determination of methocarbamol and aspirin in presence of their pharmacopeial-related substances in combined tablets using novel HPLC-DAD method.

Objective and Significance: Methocarbamol (MET) and aspirin (ASP) are widely used as a muscle relaxant combination. The USP reports guaifenesin (GUA) and salicylic acid (SAL) as related substances and hydrolytic products of MET and ASP, respectively. This work aimed at developing and validating a simple and sensitive RP-HPLC method for the determination of both drugs as well as their related substances (at their pharmacopeial limits) in their bulk powders, laboratory prepared mixtures, and MET-ASP combined tablets.

High-performance thin-layer chromatographic methods for the determination of febuxostat and febuxostat/diclofenac combination in human plasma.

Two simple, sensitive and specific high-performance thin-layer chromatographic (HPTLC) methods were developed for the determination of febuxostat (FEB) individually, and simultaneously with diclofenac (DIC) in human plasma. Method A presents the first HPTLC-ultraviolet attempt for FEB determination in human plasma. FEB was separated from endogenous plasma components (at hR = 70) with ethyl acetate-methanol-water (9:2:1, v/v) mixture as mobile phase and quantified by densitometry at its λ (315 nm).

HPTLC and Spectrophotometric Estimation of Febuxostat and Diclofenac Potassium in Their Combined Tablets.

An accurate, precise, rapid, specific and economic high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitative determination of febuxostat (FEB) and diclofenac potassium (DIC). The chromatographic separation was performed on precoated silica gel 60 GF254 plates with chloroform-methanol 7:3 (v/v) as the mobile phase. The developed plates were scanned and quantified at 289 nm.

Derivative-ratio spectrophotometric method for the determination of ternary mixture of aspirin, paracetamol and salicylic acid.

A derivative spectrophotometric method was developed for the assay of a ternary mixture of aspirin (ASP), paracetamol (PAR) and salicylic acid (SAL). The method is based on the use of the first and second derivatives of the ratio spectra and measurement at zero-crossing wavelengths. The ratio spectra were obtained by dividing the absorption spectrum of the mixture by that of one of the components.

Spectrophotometric determination of binary mixtures of pseudoephedrine with some histamine H1-receptor antagonists using derivative ratio spectrum method.

A derivative spectrophotometric method is developed for the assay of three binary mixtures of pseudoephedrine with fexofenadine (mix I), cetirizine (mix II) and loratadine (mix III). The method is based on the use of the first derivative of the ratio spectrum. The ratio spectrum was obtained by dividing the absorption spectrum of the mixture by that of one of the components.