Use of Humidified Air in Optimizing APCI−MS Response in Breath Analysis

• Published in: Journal of agricultural and food chemistry 2000-11, Vol.48 (11), p.5389-5395
• Main Authors: Zehentbauer, G, Krick, T, Reineccius, G. A
• Format: Article
• Language: English
• Subjects: Air; Aroma and flavouring agent industries; Biological and medical sciences; Breath Tests - instrumentation; Breath Tests - methods; Food industries; Fundamental and applied biological sciences. Psychology; Humans; Humidity; Mass Spectrometry - methods; Odorants - analysis; Respiration
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf000464g

An atmospheric-pressure chemical ionization−mass spectrometer (APCI−MS) system was modified to introduce gaseous samples as well as to humidify sheath and auxiliary gases. Solutions of single odorants in pentane were evaporated inside a vessel in a dry environment (relative humidity 0−10%) and in a human-breath-like environment (relative humidity 88−98%) and subsequently analyzed in the positive ion mode. The results indicated that using dry nitrogen as sheath and auxiliary gases led to strong fragmentation of the molecules combined with a low sensitivity of detection. Humidification of both gases not only increased sensitivity but also resulted in the protonated molecular ion as the base peak in 5 of the 6 compounds studied (ethyl butyrate, 3-methyl-3-phenyl glycidic acid ethyl ester, γ-decalactone, (E)-2-hexenal, and cinnamic aldehyde). Only hexanal, which formed a cluster (m/z 183), did not have the protonated molecular ion as base peak. It was found that the humidity of the sample itself did not have any influence on sensitivity or fragmentation. Keywords: APCI−MS; humidification; flavor; aroma release