Quantification of acetonitrile in exhaled breath and urinary headspace using selected ion flow tube mass spectrometry

A study has been carried out of acetonitrile in exhaled breath and in the headspace of urine from several cigarette smokers and several non-smokers using selected ion flow tube mass spectrometry (SIFT-MS). The ion chemistry involved in the detection and quantification of acetonitrile in the gas phase by SIFT-MS using H3O+ ions is outlined. Further to this, experiments have been carried out to determine the Henry's Law partition coefficients for dilute aqueous solutions of acetonitrile, which allow the determination of liquid phase urinary acetonitrile concentrations from headspace concentrations. The results of this study show that acetonitrile is readily detected by SIFT-MS in the breath and urinary headspace of smokers at levels dependent on the cigarette consumption, but is practically absent from the breath and urine headspace of non-smokers. Exploiting the measured values of the Henry's Law partition coefficients, the urinary phase concentrations have been deduced. The results of this study show that typical breath concentrations of acetonitrile are within the range 17-124 ppb (mean value 69 ppb), which are in close agreement with previous studies. The urinary acetonitrile concentrations are within the range 0-150 mug/L (mean value 57 mug/L), which are close to the concentrations determined previously in blood. These collected data imply that the acetonitrile is equilibrated amongst the body fluids (blood, total body water and urine) and that excretion occurs via both exhaled breath and urine. (C) 2003 Elsevier Science B.V. All rights reserved.