Simultaneous determination of tenoxicam and 2-aminopyridine using derivative spectrophotometry and high-performance liquid chromatography.

Derivative spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine tenoxicam and one of its decomposition products (2-aminopyridine) simultaneously and in the presence of each other. The derivative procedure was based on the linear relationship between the tenoxicam concentration and the second derivative amplitudes at 390-348 nm (peak-to-trough) measurement. The 2-aminopyridine was determined through measuring the second derivative amplitude at 241 nm (zero-crossing for tenoxicam).

Spectrophotometric determination of acrivastine in urine and capsules.

Three sensitive and accurate spectrophotometric methods are presented for the determination of the antihistaminic acrivastine (ACR) in capsules and urine. The first method utilizes the reaction of 2-nitrophenylhydrazine hydrochloride in presence of dicyclohexylcarbodiimide and pyridine. The violet colour of the resulting acid hydrazide is measured at 550 nm.

Detection and determination of interfering 5-hydroxymethylfurfural in the analysis of caramel-coloured pharmaceutical syrups.

A comparison between different caramels described for use in the pharmaceutical industry is presented. An interfering substance, 5-hydroxymethylfurfural (5-HMF), was detected in some caramels. Conditions and proofs for the formation of 5-HMF are presented.

Determination of mepyramine, aminophenazone, nialamide and chloroquine using the deltapj method.

Mepyramine maleate, aminophenazone, nialamide and chloroquine phosphate are examples of compounds which do not fulfil the requirements of the delta A method. By the proper choice of polynomial and wavelengths, the deltapj method has been successfully applied to their determination. The mean percentage recoveries were found to be 100.

Spectrophotometric determination of some preservatives in milk.

Benzoic acid, propyl p-hydroxybenzoate, and sorbic acid in milk have been determined by using the corresponding first derivative curves of absorption spectra of clarified milk samples. The delta A/delta lambda curves were computed and the concentration of each preservative was calculated using 1 point, 2 points, and/or 3 points. In all cases, the percentage error was within 2.