Quantitation of alcohols and acetone in postmortem blood and urine using headspace gas chromatography mass spectrometry.

Abstract

Traditionally, ethanol and related compounds have been analyzed by headspace gas chromatography with flame ionization detection. However, this does not provide structural information, relying solely on retention time for identification. With a mass spectrometry (MS) detector, isotope labeled internal standards can be used, eliminating the risk associated with using internal standards like 1-propanol, that can be present in postmortem samples. Furthermore, the use of ion ratios for confirmation of identity eliminates the need for dual injections on columns with different selectivity. In addition, the MS detector provides the ability to include a full scan which could be helpful in the identification of other volatile unknowns. This prompted the implementation of a headspace gas chromatographic-mass spectrometric method quantifying methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and acetone while enabling the qualitative detection of a number of other volatiles. A 100 µl sample aliquot was dispensed into a 20 mL headspace vial together with 1000 µL of internal standard solution. Samples were analyzed using an Agilent 7697A headspace sampler coupled to an Agilent Intuvo 9000 gas chromatograph and an Agilent 5977 mass spectrometer. The developed method was successfully validated and compared to current methodology before being implemented into routine analysis. The introduction of quantitative determination of putrefactive alcohols enables prospective studies of the possible relationship between the formation of ethanol and 1-propanol and 1-butanol and increased the diagnostic power of the method. The simultaneous detection of other volatiles important in postmortem toxicology in all cases increased the scope of routine analysis and the use of mass spectrometry improved the identification of analytes.