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Total blood carbon monoxide (TBCO) showed promising results in improving accuracy of CO determinations in blood and presenting better stability to different storage conditions. Therefore, it was proposed as an alternative biomarker to carboxyhemoglobin (COHb) for CO poisoning diagnosis. However, given that current interpretation reference values exist for COHb only, it is difficult to implement TBCO analysis in routine. Therefore, we aimed at determining TBCO reference values for postmortem CO poisoning cases. A previously validated method for TBCO analysis via gas chromatography–mass spectrometry was applied to cardiac, peripheral, cranial and spleen blood samples collected from 92 autopsies. Autopsy cases included 21 non-CO-related and 71 CO-related cases with varying postmortem intervals (PMIs). Statistical analyses were performed using statistical software R Studio. When comparing lower to higher PMIs for non-CO-related cases, no significant differences were found, which suggests that CO formation or degradation at low PMIs does not occur. Spleen blood showed potential as an alternative matrix to CO determinations in cases with sample availability issues but needs to be evaluated for CO-positive cases. Results for cardiac blood in CO-related autopsies showed a positive correlation between COHb and TBCO values (R  = 0.78). This value is lower than what is found in the literature, suggesting that even though COHb and TBCO are correlated, a potential underestimation of the true CO exposure might occur if only COHb values are taken into consideration. Samples were divided into CO exposure groups based on COHb concentrations, and with the data obtained, classification into the following TBCO concentration groups is proposed: no significant CO exposure case <6 µmol/mL, medium CO exposure case 6–20 µmol/mL and high CO exposure case >20 µmol/mL. Even if a higher number of samples in each group would enable to increase the confidence, these results are very promising and highlight the importance of TBCO measurement. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.forsciint.2009.07.023 Byline: Ronald Agius (a), Thomas Nadulski (a), Hans-Gerhard Kahl (a), Johannes Schrader (b), Bertin Dufaux (a), Michel Yegles (c), Fritz Pragst (d) Keywords: Ethyl glucuronide; Hair analysis; Forensic validation; HS-SPME-GC-MS/MS; Alcohol marker; Quality control; Error estimation Abstract: The analysis of ethyl glucuronide (EtG) in hair is a powerful tool for chronic alcohol abuse control because of the typical wide detection window of the hair matrix and due to the possibility of segmentation, allowing evaluation of alcohol consumption in different periods. Additionally, EtG in hair is often the only diagnostic parameter of choice for alcohol abuse when other clinical parameters such as ALT, AST, [gamma]GT and CDT (asialotransferrin and disialotransferrin) are in the normal range and EtG in urine negative. In this paper, we describe the development, optimization and validation of a new method based on hair extraction with water, clean-up by solid phase extraction (SPE), derivatization with heptafluorobutyric anhydride and headspace solid-phase microextraction (HS-SPME) in combination with GC-MS/MS according to forensic guidelines. The assay linearity of EtG was confirmed over the range from 2.8 to 1000pg/mg hair, with a coefficient of determination (r.sup.2) above 0.999. The LLOQ was 2.8pg/mg and the LLOD was 0.6pg/mg. An error profile calculated according to the 'Guide to the Expression of Uncertainty in Measurement' (GUM) at 99% confidence intervals for the range 5-750pg/mg hair did not exceed 10%. This range corresponds to more than 98% of the positive samples analysed. Author Affiliation: (a) Labor Krone, Siemensstr. 40, 32105, Bad Salzuflen, Germany (b) Sanitatsdienst der Bundeswehr Kiel, AuAenstelle Berlin, Germany (c) Laboratoire National de Sante, Toxicologie, Luxembourg (d) Institut fur Rechtsmedizin, Charite Berlin, Germany Article History: Received 12 June 2009; Accepted 28 July 2009