Comparison of SPME and static headspace analysis of blood alcohol concentration utilizing two novel chromatographic stationary phases

Headspace gas chromatography, coupled to flame ionization detection (GC-FID) analysis of blood alcohol concentration is a routine analysis carried out in forensic laboratories. A common concern with this analysis is the possible co-elution of a variety of other commonly encountered compounds with the target compound ethanol. By use of application specific columns, improved separation of ethanol, as well as the other potential components can be achieved. The presented method includes the evaluation of blood alcohol concentration by both direct gas headspace and SPME utilizing a new combination of GC columns. An investigation of method detection limits (MDLs) was also conducted in order to determine a reporting limit as well as the degree of uncertainty at the common threshold value of 0.08 g/dL. The study showed that under the conditions of this work, static headspace analysis with the use of t-butanol as an internal standard provided the most accurate and precise data with an MDL of 0.002 g/dL for the Rtx(®) - BAC PLUS 1 column and 0.005 g/dL for the Rtx(®) - BAC PLUS 2 column. The study also showed that the SPME analysis using a Carboxen/PDMS (65 μm) fiber with the use of t-butanol provided the lowest overall MDL of 0.0006 g/dL for both Rtx(®) - BAC PLUS 1 and 2 columns without loss of accuracy or precision.