Determination of aldehydes in human breath by on-fibre derivatization, solid-phase microextraction and GC–MS

A GC–MS method for the simultaneous determination of hexanal, heptanal, octanal, nonanal and decanal in exhaled breath was established and validated. The aldehydes were derivatized on PDMS/DVB fibres using O-2,2,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) as the headspace derivatization reagent. The resultant oximes were quantified by GC–MS in selected ion monitoring (SIM) mode. The method provides detection limits of 0.01–0.03 nM for the aldehydes, with a linear response in the concentration range 0.002–20 nM. Within-day precision values for the five aldehydes at 0.02–0.04 nM and 0.2–0.4 nM were in the ranges: 3–9% and 3–8%, respectively; the corresponding between-day precision values were 11–22% and 10–24%. Exhaled breath samples could be stored at −20 °C for 48 h.