ENHANCED SENSITIVITY IN THE ANALYSIS OF TRACE ORGANOCHLORINE COMPOUNDS BY NEGATIVE-ION MASS-SPECTROMETRY WITH AMMONIA AS REAGENT GAS

A comparison of the performances of ammonia and methane as reagent gas es for the analysis of trace organochlorine compounds by gas chromatog raphy coupled to negative-ion chemical ionization mass spectrometry is performed in the present study. Examples of standard mixtures and hum an blood samples analyzed with both reagents in scan and selected-ion monitoring mode are shown. Important advantages are observed as a cons equence of the use of ammonia. These concern detection and quantitatio n limits and the lower dependence of sensitivity on the degree of chlo rine substitution of the compounds. (C) 1998 Elsevier Science B.V. All rights reserved.