Quantification of breath isoprene using the selected ion flow tube mass spectrometric analytical method.

We have used our selected ion flow tube mass spectrometric method (SIFT-MS) to study isoprene levels in the alveolar breath of 29 healthy volunteers during normal working hours at the varying states of nutrition occurring during this period. Quantification of the breath isoprene was achieved using O(2)(+) precursor ions to avoid complications which can arise when using H(3)O(+) precursor ions for isoprene analysis. The present data indicate that the spread of the alveolar isoprene levels in this sample of healthy individuals is 22 to 234 ppb and that the mean value is 83 ppb with a standard deviation of 45 ppb. These levels are compared with those previously determined using other techniques and are seen to be at the low end of the values previously reported. The present studies are a prelude to an investigation of the proposed correlation of breath isoprene levels with psychological, physical and biochemical stress. Copyright 1999 John Wiley & Sons, Ltd.