Validation of an alcohol dehydrogenase method for forensic blood alcohol determination on Thermo Scientific Indiko analyzer and comparison with Technikon autoanalyzer

Aim: In context of restructuring the local forensic toxicological laboratory services a suitable and automatable method for determination of blood alcohol concentration had to be established. As alcohol dehydrogenase method the DRI-Ethanol Assay (Microgenics) on Indiko Analyzer (Thermo Scientific) was chosen. The aim of this study was to validate this method and compare the results with those of the currently used method using Technikon Autoanalyzer. Methods: Serum or aqueous ethanol solutions were used for determination of ethanol without prior treatment and the blood alcohol concentration was measured automatically on both systems. Calculations were executed with VALISTAT. Results: For the Indiko Analyzer, accuracy measurement with serum control samples containing 0.50 or 2.00 g ethanol/L on 9 days yielded a mean result of 0.52 +/- 0.02 g/L and 1.98 +/- 0.06 g/L, respectively. The relative standard deviation (RSD) was 3.1% (0.50 g/L) and 3.2% (2.00 g/L); bias was 3.3% and -1.2%, respectively. Repeatability was calculated with RSD = 0.00% for both controls. The intermediate precision was RSD = 2.1% (0.50 g/L) and RSD = 1.5% (2.00 g/L). These validation parameters were similar to those values obtained for the Technikon Autoanalyzer in a preceding study. The results obtained for 93 authentic forensic serum specimens measured on both systems provide a linear regression equation of y=1.0202x-0.0087 and show an excellent correlation of r=0.9977. The Limit of Detection was 0.00 g/L and the Limit of Quantification 0.01 g/L for both ADH methods. Conclusion: Precision and reproducibility of the ADH method on the Indiko Analyzer meet the requirements for BAC determination in forensic specimens and were comparable to our currently used ADH method.