Blood alcohol testing: comparison of the performance obtained with the different methods used in the Belgian external quality assessment schemes.

This study describes the performance of the different methods used for blood alcohol analysis by the Belgian laboratories participating in the external quality assessment scheme. The best performance was achieved by the gas chromatography (GC) and the enzymatic methods. The enzymatic methods are easier to use but more apparatus-dependent, whereas GC methods display higher precision, especially at concentrations near the critical legal limit of 0.5 g/l. The study highlights the need to introduce a methodology other than the chemical oxidation-based method of Casier, the sole legal method for forensic analyses in drinking-driving cases in Belgium. This method with poor intra-laboratory, inter-laboratory and linearity performances has definitely become obsolete. Even though GC clearly appears as the method of choice, mainly due to its higher specificity, the present study also shows the need for practical guidelines to improve the quality of GC alcohol analyses used in Belgium.