Determination of phosgene in methylene chloride after cyclisation with a 2-hydroxyamine and gas chromatography with nitrogen-selective detection

Abstract

A convenient and simple method for the determination of phosgene in methylene chloride has been developed. An aliquot of the sample is mixed with a solution of metoprolol or 2-aminophenol, in an excess. After a reaction time of 10 min the solution is taken to dryness and the cyclic derivative analysed by gas chromatography with nitrogen-selective detection. The precisions (relative standard deviation) at the 40 and 10 ng ml^–1 levels were 3.9 and 7.3% for metoprolol and 3.3 and 3.6% for 2-aminophenol, respectively. The absolute yields at the 40 ng ml^–1 level were 91 and 95%, respectively. The present limit of detection is approximately 1 ng ml^–1. Phosgene appeared in methylene chloride (>2 ng ml^–1) stabilised with 20 p.p.m. of amylene within 3 d if stored in clear glass in the presence of daylight. After 15 d the 100 ng ml^–1 level was reached.