CHLOROACETONITRILE AS ELUENT ADDITIVE IN THERMOSPRAY LIQUID-CHROMATOGRAPHY NEGATIVE-ION MASS-SPECTROMETRY FOR THE CHARACTERIZATION OF CHLORINATED ORGANIC POLLUTANTS

The use of chloroacetonitrile as eluent additive in thermospray liquid chromatography/mass spectrometry in the negative ion mode using filament‐off, filament‐on and discharge ionization modes has been studied with chlorophenols and chlorinated phenoxy acids as test compounds. In the absence of chloroacetonitrile from the eluent, different base peaks were observed corresponding to [ M  H]−, [ M + H]− and [ M + CH3COOO]−, while in the presence of 2% chloroacetonitrile [M + Cl] − was the base peak in most cases when using the filament‐on and discharge ionization modes and had a maximum value of 30% relative abundance in the filament‐off mode. Most chloride attachment ([ M + Cl] − ion) was always observed in the filament‐on mode. Other ions observed were adduct ions with the ionizing additive (ammonium acetate) such as [M + CH3COO]− and [ M + (CH3COOH). (CH3COO)]− when the eluent contained no chloroacetonitrile and [ M + (CH3COOH). Cl]− when 2% chloroacetonitrile was present. The use of chloroacetonitrile in the eluent provides additional structural information in thermospray liquid chromatography/negative ion mass spectrometry. It does not cause any appreciable loss in sensitivity during flow injection or chromatographic analysis. Copyright © 1990 John Wiley & Sons, Ltd.