Analytical artifacts caused by the presence of water vapor in the headspace of food products

Artifacts due to water that appear during analysis by purge-and-trap/GC/MS of naturally moist products were reproduced by increasing the relative humi dity of the headspace of measuring cell containing dry and low-moisture pro ducts (dehydrated beef stock and powdered Parmesan cheese) by means of a pi ece of moistened glass wool. The changes observed in the chromatographic pr ofiles of the dry products after humidifying the headspace are explained by interactions between volatile compounds, water and the adsorption trap dur ing the purge-and-trap step.