Trace analysis of the antihistamines methapyrilene hydrochloride, pyrilamine maleate and triprolidine hydrochloride monohydrate in animal feed, human urine and wastewater by high-performance liquid chromatography and gas chromatography with nitrogen-phosphorus detection.

Toxicological evaluation of the antihistamines methapyrilene hydrochloride, pyrilamine maleate, and triprolidine hydrochloride monohydrate using methapyrilene hydrochloride as the positive indicator was investigated as part of a structure-activity relationship study in rats and mice. Prerequisites for the toxicological tests were the development of analytical procedures to certify the dose, homogeneity and stability of the drugs in animal feed and to monitor human urine for possible exposure and to ensure removal of the test agents from wastewater prior to its discharge into the environment. A high-performance liquid chromatographic (HPLC) system was developed using a fluorescence detector for the determination of methapyrilene hydrochloride and pyrilamine maleate in feed at levels as low as 100 ng/g and in human urine as low as 1 ng/g. An HPLC-UV procedure was developed for the determination of triprolidine hydrochloride monohydrate in feed at levels as low as 10 micrograms/g. Data concerning p-values, extraction efficiencies from feed and stability experiments in feed are presented for these antihistamines. A gas chromatographic procedure using a nitrogen-phosphorus detector was also developed for determining the three antihistamines in admixture in wastewater at levels as low as 10 ng/g.