Abstract
IntroductionMeasurements of blood ethanol concentrations must be accurate and reliable. The most important factors affecting blood ethanol stability are temperature and storage time. In this study, we aimed to compare ethanol stability in plasma samples at -20 °C for the different storage periods.Materials and methodsBlood samples were collected from intoxicated drivers (N = 80) and initial plasma ethanol concentrations were measured immediately. Plasma samples were then stored at -20 °C and re-assessed after 2, 3, 4, or 5 months of storage. Differences between the initial and stored ethanol concentrations in each group (N = 20) were analyzed using Wilcoxon matched-pairs test. The deviation from the initial concentration was calculated and compared with Clinical Laboratory Improvement Amendments (CLIA’88) Proficiency Testing Limits. Relationships between the initial concentrations and deviations from initial concentrations were analyzed by Spearman’s correlation analysis. For all statistical tests, differences with P values of less than 0.05 were considered statistically significant.ResultsStatistically significant differences were observed between the initial and poststorage ethanol concentrations in the overall sample group (P < 0.001). However, for the individual storage duration groups, analytically significant decreases were observed only for samples stored for 5 months, deviations from the initial concentrations exceeded the allowable total error (TEa). Ethanol decreases in the other groups did not exceed the TEa.ConclusionAccording to our results, plasma ethanol samples can be kept at -20 °C for up to 3-4 months until re-analysis. However, each laboratory should also establish its own work-flow rules and criterion for reliable ethanol measurement in forensic cases.
Highlights
Measurements of blood ethanol concentrations must be accurate and reliable
According to our results, plasma ethanol samples can be kept at -20 °C for up to 3-4 months until re-analysis
Deviations from the initial concentrations that exceed the TEa were observed in group I (G I) and group II (G II); these results were considered as analytically significant
Summary
Measurements of blood ethanol concentrations must be accurate and reliable. In traffic accidents, measurement of blood ethanol concentrations can be a deciding factor when determining who was at fault for the accident. Measurement of blood ethanol concentrations needs to be accurate and reliable [2]. The preanalytical phase (i.e., collection, transport, and storage) has a substantial role in the quality and reliability of analytical ethanol results, which depend on the quality and acceptability of specimens. These pre-analytical steps (proper sampling, handling, and storage of blood ethanol samples) are critical in forensic cases [3,4].
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