Volatile compounds released by Nalophan; implications for selected ion flow tube mass spectrometry and other chemical ionisation mass spectrometry analytical methods.

Abstract

Three analytical techniques were used to analyse the VOCs released into the nitrogen used to expand Nalophan bags, viz. gas chromatography/mass spectrometry (GC/MS), secondary electrospray ionization mass spectrometry (SESI-MS) and selected ion flow tube mass spectrometry (SIFT-MS). The most significant VOCs were identified and quantified by SIFT-MS as a function of storage time, temperature and humidity. The consistent results obtained by these three analytical methods identify 1,2-ethanediol (ethylene glycol) and 2-methyl-1,3-dioxolane as the major VOCs released by the Nalophan. Their concentrations are enhanced by increasing the bag storage temperature and time, reaching 170 parts-per-billion by volume (ppbv) for ethylene glycol and 34 ppbv for 2-methyl-1,3-dioxolane in humid nitrogen (absolute humidity of 5%) contained in an 8-L Nalophan bag stored at 37°C for 160 min. Using H3 O+ reagent ions for SIFT-MS and SESI-MS analyses, the following analyte ions (m/z values) are affected by the Nalophan impurities: 45, 63, 81, 89 and 99, which can compromise analyses of acetaldehyde, ethylene glycol, monoterpenes, acetoin, butyric acid, hexanal and heptane.