The vulnerability of water supplies to toxic contaminationcalls for fast and effective means for screening watersamples for multiple threats. We describe the use ofphotoionization (PI) mass spectrometry (MS) for high-speed, high-throughput screening and molecular identification of chemical weapons (CW) threats and otherhazardous compounds. The screening technology candetect a wide range of compounds at subacute concentrations with no sample preparation and a sampling cycletime of ~45 s. The technology was tested with CW agentsVX, GA, GB, GD, GF, HD, HN1, and HN3, in addition toriot agents and precursors. All are sensitively detected andgive simple PI mass spectra dominated by the parent ion.The target application of the PI MS method is as a routine,real-time early warning system for CW agents and otherhazardous compounds in air and in water. In this work,we also present comprehensive measurements for wateranalysis and report on the system detection limits, linearity, quantitation accuracy, and false positive (FP) and falsenegative rates for concentrations at subacute levels. Thelatter data are presented in the form of receiver operatingcharacteristic curves of the form of detection probability
PD versus FP probability
PFP. These measurements weremade using the CW surrogate compounds, DMMP, DEMP,DEEP, and DIMP. Method detection limits (3
) obtainedusing a capillary injection method yielded 1, 6, 3, and 2ng/mL, respectively. These results were obtained using1-
L injections of water samples without any preparation,corresponding to mass detection limits of 1, 6, 3, and 2pg, respectively. The linear range was about 3-4 decadesand the dynamic range about 4-5 decades. The relativestandard deviations were generally <10% at CW subacuteconcentrations levels.
