Quantitation and identification of organic N-chloramines formed in stomach fluid on ingestion of aqueous hypochlorite.

The chemical reactions that hypochlorite undergoes in the body when chlorinated water is ingested have received very little attention. Because amino nitrogen compounds are important components of the average diet, the reactions of hypochlorite with amino compounds in the stomach were investigated. Stomach fluid was recovered from Sprague-Dawley rats that had been fasted for 48 hr and administered 4 mL deionized water. The chlorine demand of the stomach fluid was determined. An average volume-independent demand of 2.7 mg chlorine was measured. At doses below 40 mg/L chlorine reducing reactions appeared to account for reduction of all oxidizing species within 15 min as measured by the FAS-DPD titrimetric method. At least part of the chlorine demand is associated with amino acids present in the stomach fluid. Amino acids were identified and quantified in the stomach fluid by precolumn derivatization with o-phthalaldehyde and high-pressure liquid chromatography (HPLC). When stomach fluid is chlorinated to concentrations of chlorine between 200 and 1000 mg/L, organic N-chloramines are formed. After derivatization of chlorinated stomach fluid with dansyl sulfinic acid, fluorescent derivatives of chloramines were separated by HPLC. Three chloramino acid derivatives, N-chloroalanine, N-chloroglycine, and N-chlorophenylalanine, were identified by cochromatography with known standards using two chromatographic methods. The yield of a chloramine that would form in stomach fluid on administration of hypochlorite to animals was determined using tritiated piperidine and doses of 200 and 1000 mg/L chlorine. Yields of tritiated N-chloropiperidine in recovered stomach fluid were 70% and 42%, respectively, of the theoretical amount expected.