Microscale extraction of perchlorate in drinking water with low level detection by electrospray-mass spectrometry

Improper treatment and disposal of perchlorate can be an environmental haza rd in regions where solid rocket motors are used, tested, or stored. The so lubility and mobility of perchlorate lends itself to ground water contamina tion, and some of these sources are used for drinking water. Perchlorate in drinking water has been determined at sub-mu g l(-1) levels by extraction of the ion-pair formed between the perchlorate ion and a cationic surfactan t with electrospray-mass spectrometry detection. Confidence in the selectiv e quantification of the perchlorate ion is increased through both the use o f the mass based detection as well as the selectivity of the ion pair. This study investigates several extraction solvents and experimental work-up pr ocedures in order to achieve high sample throughput. The method detection l imit for perchlorate based on 3.14 sigma(n-1) of seven replicate injections was 300 ng l(-1) (parts-per-trillion) for methylene chloride extraction an d 270 ng l(-1) for methyl isobutyl ketone extraction. Extraction with methy lene chloride produces linear calibration curves, enabling standard additio n to be used to quantify perchlorate in drinking water. Perchlorate determi nation of a contaminated water compared favorably with results determined b y ion chromatography. (C) 2000 Elsevier Science B.V. All rights reserved.