Sample handling and storage for the quantitative analysis of volatile compounds in blood: the determination of toluene by headspace gas chromatography.

The problems associated with the handling and storage of blood samples for the analysis of toluene in toxicological casework using headspace gas chromatography have been investigated. Significant losses of toluene and the internal standard, ethylbenzene, from solution may be observed during handling. Toluene may be lost into the headspace above the blood in a storage container while such headspaces can also be detrimental, leading to the formation of n-hexanal, a possible interference with the assay. Large differences in the stability of toluene were seen for blood samples in different types of storage container. Storage containers in which the sample was only in contact with glass, teflon, or aluminum foil were most satisfactory. It is recommended that blood samples should be stored in appropriate containers with minimum headspace under cold conditions (4 degrees C). Transfers of blood should also be made at cold temperatures. The applicability of these guidelines to the analysis of other volatile compounds is discussed.