Impact of blood collection tubes on erroneous 1-propanol detection and on forensic ethanol analysis

 Impact of blood collection tubes on erroneous 1-propanol detection and on forensic ethanol analysis

Aim: The present study aims to emphasize the importance of selecting the proper blood collection tubes for the right intended use in order to avoid erroneous results, especially in reference to forensic alcohol analysis. Introduction: Forensic alcohol analysis in blood from living subjects is performed in various situations, such as driving under the influence, is usually related to consumption of alcoholic beverages and often results to the detection of ethanol and/or congener alcohols. Alternatively, ethanol and congeners, such as 1-propanol, can be microbially produced especially in autopsy samples. Methods: Sixty eight blood samples from living subjects, all drivers involved in traffic accidents, contained in different collection tubes, were included in the study. Volatiles were detected with a validated HS-GC-FID method. Samples of normal human blood, spiked with ethanol and/or 1-propanol, dispersed in different tubes were treated and analyzed as the authentic blood samples in order to test the suitability of the collection tubes. Results: Authentic blood samples, contained in certain tubes with separator gel, had high concentrations of “1-propanol”. It was shown that the separator gel released a substance that was recognized as “1-propanol” during analysis by HS-GC-FID at 600C (routine conditions). The erroneous “1-propanol” was separated from authentic 1-propanol during analysis at 580C. Discussion: The separator gel of certain blood collection tubes compromises a source of pre-analytical error that results to erroneous concentrations of 1-propanol. This is unfavorable in forensic cases and can complicate interpretation of the origin (exogenous or microbial) of the detected ethanol.