SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A21
ALCOHOL DETERMINATION BY HEAD SPACE DUAL COLUMN CAPILLARY GAS
CHROMATOGRAPHY
Jlpo Rasanen', Ilkka Ojanpera, Kaisa Kurkinen, Juhani Vartiovaara, Erkki Vuori
Department of Forensic Medicine, PO Box 40, FIN-00014 University of Helsinki, FINLAND
A head space dual column capillary gas chromatographic method was developed for the simultaneous
determination of ethanol, methanol, acetone, isopropyl alcohol, ethyl methyl ketone and n-propanol in
blood and urine. The method consisted of two identical instruments and conditions, but using different
internal standards, I-propanol and 2-butanol.
The gas chromatographs were 6890 Series GCs equipped with two flame ionisation detectors and
ChemStation software (Agilent Technologies, USA). The autosamplers were Combi Pal Head space
samplers (CTC Analytics, Switzerland). The parallel capillary columns were a Rtx-BACI, 30m x 0.53mm,
3 !lm film and a Rtx-BAC2, 30m x 0.53mm, 2 !lm film (Restek, USA). The columns were connected to
single injector with a Graphpack Divider (Gerstel, Germany). The head space conditions were as follows:
incubation temperature 60 °C, incubation time 5 min (agitation speed 500 rpm), syringe temperature 65 °C,
injection volume 500 !ll. The GC conditions were as follows: split ratio I :20, column flow rate 10.7 mllmin
(He), injection port temperature 200 °C, oven temperature 45°C (4 min), detector temperature 250°C, H2
flow 40 ml/min, air flow 450 mllmin, make-up flow (N2) 45 mllmin. The total analysis time was 5 min 50
s.
A baseline separation was obtained for all six compounds on both columns. Thirty-eight compounds were
tested for interference. Methyl acetate co-eluted with I-propanol on Rtx-BACI and with acetone on Rtx­
BAC2. No other compound was found to co-elute with an analyte on both columns. However, ten
compounds co-eluted with an analyte on one column. The reporting limit was set to 0.2 mg/g for ethanol
and 0.1 mglg for the other analytes. The method was accredited for the determination of ethanol in blood
and urine according to the standard SFS-EN ISO/IEC 17025. The uncertainty of measurement was 4 % for
both blood and urine samples.
The present method takes advantage of the facility of the head space sampling by gas-tight syringe over
loop or pneumatic systems. Two dual-column instruments with different internal standards comprise a
reliable but still compact set up for forensic alcohol determination.
Key words: Head space GC, Blood alcohol, Capillary column
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