Effect of Water Vapor Content and Gas Composition on Quantification of Volatile Organic Compounds from Wild Rocket by SPME

Abstract

A quantification method based on solid-phase microextraction (SPME) and external standard calibration for analysis of volatile organic compounds (VOCs) emitted from fresh produce in a dynamic environment, such as during storage in modified atmosphere (MA) packages, was investigated in this study. The effects of the water vapor content, temperature, and gas matrix composition on the extraction efficiencies of dimethyl sulfide, nitromethane, 3-methylfuran, dimethyl disulfide, and ethyl 3-methylbutyrate were investigated on an 85-μm carboxen/polydimethylsiloxane fiber. At VOC concentrations of 15.7 to 32.7 ng L−1, the water vapor content and temperature had negative effects on the extraction efficiency of dimethyl sulfide and nitromethane. At high CO2 concentrations (20–50 % CO2 balanced with N2), the extraction efficiency for all of the investigated VOCs decreased. However, the VOC concentrations determined from a 10 % O2 and 10 % CO2 matrix were the same as those measured in 20 % O2 and 0 % CO2 or 0 % O2 and 20 % CO2 matrices. For quantification of VOCs emitted from wild rocket stored under dynamic gas concentrations, a gas matrix composed of 10 % O2 and 10 % CO2 with a relative humidity above 85 % can be used for external standard calibration by maintaining the same temperature during the extraction of VOCs from the samples, as well as during the calibration.