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Comparison of blood ethanol stabilities in different storage periods.

Kocak FE, Isiklar OO, Kocak H, Meral A - Biochem Med (Zagreb) (2015)

Bottom Line: The deviation from the initial concentration was calculated and compared with Clinical Laboratory Improvement Amendments (CLIA'88) Proficiency Testing Limits.For all statistical tests, differences with P values of less than 0.05 were considered statistically significant.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).

View Article: PubMed Central - PubMed

Affiliation: Dumlupinar University, Faculty of Medicine, Department of Medical Biochemistry, Kutahya, Turkey.

ABSTRACT

Introduction: Measurements 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 methods: Blood 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.

Results: Statistically 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.

Conclusion: According 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.

Show MeSH
Mean decreases (%) in plasma ethanol concentrations from initial concentrations according to periods of storage, and comparisons with allowable total error (TEa) according to CLIA’88 (± 25%).
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f1: Mean decreases (%) in plasma ethanol concentrations from initial concentrations according to periods of storage, and comparisons with allowable total error (TEa) according to CLIA’88 (± 25%).

Mentions: Mean decreases (%) in plasma ethanol concentrations from initial concentrations according to storage duration and comparisons with TEas according to CLIA’88 (± 25%) are shown in Figure 1. Deviations from the initial concentrations that exceed the TEa were observed in G I (in 11 of 20 tubes) and G II (in 4 of 20 tubes); these results were considered as analytically significant. The deviations were within the acceptable ranges in G III and G IV; therefore, these results were considered not analytically significant. Additionally, the mean decreases in ethanol concentrations were directly proportional to the storage period. Mean decreases (%) in ethanol concentrations according to storage periods are shown in Figure 2.


Comparison of blood ethanol stabilities in different storage periods.

Kocak FE, Isiklar OO, Kocak H, Meral A - Biochem Med (Zagreb) (2015)

Mean decreases (%) in plasma ethanol concentrations from initial concentrations according to periods of storage, and comparisons with allowable total error (TEa) according to CLIA’88 (± 25%).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401314&req=5

f1: Mean decreases (%) in plasma ethanol concentrations from initial concentrations according to periods of storage, and comparisons with allowable total error (TEa) according to CLIA’88 (± 25%).
Mentions: Mean decreases (%) in plasma ethanol concentrations from initial concentrations according to storage duration and comparisons with TEas according to CLIA’88 (± 25%) are shown in Figure 1. Deviations from the initial concentrations that exceed the TEa were observed in G I (in 11 of 20 tubes) and G II (in 4 of 20 tubes); these results were considered as analytically significant. The deviations were within the acceptable ranges in G III and G IV; therefore, these results were considered not analytically significant. Additionally, the mean decreases in ethanol concentrations were directly proportional to the storage period. Mean decreases (%) in ethanol concentrations according to storage periods are shown in Figure 2.

Bottom Line: The deviation from the initial concentration was calculated and compared with Clinical Laboratory Improvement Amendments (CLIA'88) Proficiency Testing Limits.For all statistical tests, differences with P values of less than 0.05 were considered statistically significant.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).

View Article: PubMed Central - PubMed

Affiliation: Dumlupinar University, Faculty of Medicine, Department of Medical Biochemistry, Kutahya, Turkey.

ABSTRACT

Introduction: Measurements 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 methods: Blood 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.

Results: Statistically 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.

Conclusion: According 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.

Show MeSH