Problems of Forensic Sciences 2012 Vol. 89 (LXXXIX) 86-98
GAS CHROMATOGRAPHIC DETERMINATION OF CARBOXYHAEMOGLOBIN (COHb) IN POST-MORTEM BLOOD SAMPLES
Juliusz ADAMSKI, Dariusz ZUBA
Institute of Forensic Research, Kraków, Poland
Streszczenie
A method for carboxyhaemoglobin (COHb) determination in post-mortem blood samples by headspace gas chromatography with the use of a methanizer and flame ionization detector (FID) was proposed. COHb concentration was determined by referring the analytical signal obtained for a blood sample to a calibration curve, which had been prepared using a portion of the (same) analysed blood sample that had been completely saturated with CO. Development of the method encompassed optimization of the sample preparation procedure and instrumental parameters. Analytical characterization of the developed method was also performed. It was additionally shown that preliminary reduction of oxidized forms of haemoglobin by addition of sodium dithionite is the key factor influencing method accuracy. The applied procedure ensures selectivity and specificity. It was also shown that the method was precise, with the coefficients of variation between 1.2% (for 50% COHb in blood) and 6.5% (for about 1% COHb). Linearity was obtained from LOQ (about 0.9% COHb) to 100% COHb. Accuracy was assessed by comparison of the results obtained by the proposed procedure with alternative methods, i.e. the Hartridge reversion spectroscope and the spectrophotometric method by Fretwurst and Meinecke, which showed that the proposed assay can be applied even to the analysis of highly decomposed post-mortem blood samples.