Nosespace with an ion trap mass spectrometer-quantitative aspects

Abstract A new APCI source and interface connected to an ion trap mass spectrometer have been designed in order to allow introduction and analysis of a gaseous flow within the source. In vitro detection limits, linear response ranges and repeatability (daily and day-to-day) have been determined for a set of flavour molecules of various chemical classes. Detection limits and linear response ranges have been found compatible with aroma compounds concentrations generally found in foodstuffs. Repeatabilities were found within the values already published for another interface connected to an ion trap mass spectrometer. During breath-by-breath data acquisition it appeared clearly that some competition between volatiles towards the chemical ionisation process occured. This point has been addressed specifically. Mixtures of 2-heptanone, ethyl hexanoate, 2,3,5-trimethylpyrazine and 2-heptanol in varying concentration ranges have been analysed and their responses compared to pure compound responses. In the case of 2-heptanol, it clearly appeared that its APCI-MS response decreased when ethyl hexanoate concentration increased in the mixture.