High-performance liquid chromatographic determination of memantine in human urine following solid-phase extraction and precolumn derivatization.

A validated HPLC-UV method is presented for the quantification of urinary memantine hydrochloride, a novel medication approved to treat moderate and advanced cases of Alzheimer's disease. The drug and amantadine hydrochloride, the internal standard, were extracted from human urine using SPE. The extract was then buffered and derivatized at room temperature using o-phthalaldehyde in the presence of N-acetyl-L-cyteine.

A rapid first-derivative spectrophotometric analysis of cephalexin and cephradine in human urine.

A rapid, simple, and accurate first-derivative spectrophotometric method has been established for the determination of either cephalexin or cephradine in urine. Quantitative analysis of each antibiotic was achieved by measuring the peak amplitude at 268 nm. The relative and absolute recoveries ranged from 98.

Application of some colorimetric methods for the spectrophotometric determination of phenylbutazone and oxyphenbutazone.

Two methods for determination of phenylbutazone and oxyphenbutazone are described. In the first, naphthoquinone reacts with the product of acid hydrolysis of phenylbutazone or oxyphenbutazone to give an orange colour, having maximum absorption at 480 and 465 nm respectively. In the second, lead tetra-acetate reacts with the hydrolysis product of phenylbutazone (benzidine) to develop a green colour which on heating or addition of excess of reagent changes to yellow, with maximum absorption at 340 nm.

Some spectrophotometric methods for determination of certain antipyretic and antirheumatic drugs.

Heating paracetamol in strongly alkaline medium with 4-nitrosoantipyrine gives a red colour with maximum absorption at 515 nm. Mefenamic and flufenamic acids can be determined colorimetrically after extraction as ion-pairs with Methylene Blue.