Improper sealing caused by the Styrofoam integrity seals in leakproof plastic bottles lead to significant loss of ethanol in frozen evidentiary urine samples.

Department of Chemistry, St. Cloud State University, St. Cloud, MN 56301-4498, USA.
Journal of Forensic Sciences (Impact Factor: 1.16). 06/2003; 48(3):672-6.
Source: PubMed


Evidentiary urine samples (n = 345) stored frozen at -20 degrees C in their original containers (leakproof 100 mL plastic bottles) upon retesting for ethanol resulted in concentrations that were significantly lower (average loss = approximately 30%) than those prior to their storage at -20 degrees C (p < or = 0.0001). The observed loss of ethanol was independent of the method of thawing or the concentration of ethanol in the samples, but was dependent on the sample volume in the container, i.e., the larger the volume of sample the larger the magnitude of ethanol loss. The loss of ethanol was determined to be due to improper sealing by a Styrofoam integrity seal attached to the mouth of the container. Accordingly, adopting leakproof plastic containers that do not contain Styrofoam integrity seals, but rather an outside and across the cap tape integrity seal for evidence collection and long-term storage, will prevent loss of ethanol due to evaporation.

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    • "This aspect is a of fundamental importance, especially in developing countries in which the collection and conservation of blood samples are frequently deficient and in which preserving agents such as sodium fluoride are rarely used. Other authors argue that, if samples are conveniently collected and put in adequate, properly sealed containers, ethanol decay is not significant during storage [2] [3] [4]. "
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    • "The reliability of the BAC value is dependent on factors not accounted for in this study, namely: (i) post mortem ethanol production (Briglia, Bidanset, & Dal Cortivo, 1992; Canfield, Kupiec, & Huffine, 1993) (ii) source of blood sample, i.e., heart, or peripheral blood vessel (Briglia et al., 1992) (iii) collection and storage of biological samples (Sreerma & Hardin, 2003) and (iv) type of biological fluid, i.e., urine, blood, vitreous humor, etc. (Hardin, 2002). Common to all of the aforementioned factors is the fact that gross trauma, as could be expected in a traffic accident involving a fatality, is a significant factor in the value of the reported BAC (Winek, Winek, & Wahba, 1995). "
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