Direct sampling ion trap mass spectrometry for the rapid determination of volatile organics in environmental matrices

Analytical methods are currently being developed for the rapid determination of part-per-billion or lower levels of volatile organics in water, soil, air, and oil samples using direct sampling in combination with a RF quadrupole ion trap mass spectrometer (ITMS). Features of the ITMS which are important to the success of these applications include the ability to perform selective chemical ionization, high efficiency collision induced dissociation (MS/MS) experiments, excellent instrument reliability and tolerance to relatively high operating pressures. Excellent detection limits, linearity of response, and reproducibility have been demonstrated for the determination of volatiles in water, soil, and air. Because no chromatography is used, sample turn-around is typically less than 5 minutes. Direct sampling is accomplished with a split-open-split capillary restrictor interface which has been designed to accept a wide variety of sampling devices. Volatiles in water can be determined without any sample preparation simply by direct purge with helium into the mass spectrometer sample interface. A helium flow rate of approximately 100 ml/min through a sparging device enables reproducible purging of volatiles from a 15 ml water sample in less than 3 minutes.