The history of a blood tube can materially affect ethanol reanalysis years later. Tiscione and colleagues found greater losses in previously opened tubes and tubes with lower blood volumes. Their research used preserved antemortem whole blood, so it does not establish how every decomposed autopsy specimen behaves.
The comparison involved paired tubes and two laboratories
The study used 117 forensic cases, 110 with a second tube. Blood had been collected during life for driving investigations in nominal 10 mL glass tubes containing 100 mg sodium fluoride and 20 mg potassium oxalate. Anatomical venipuncture sites were not specified.
Tube A was initially tested and later reanalyzed by the original laboratory after 5.4–10.3 years at room temperature. Previously unopened Tube B was analyzed by another laboratory after 5.6–10.5 years. The second laboratory used different instrumentation and methodology. This was authentic evidence-storage research, not a randomized experiment isolating opening as its only variable.
Prior opening was associated with greater loss
Among 100 matched ethanol-positive tube pairs used for the opening comparison, mean losses were 0.047 g/dL in previously opened Tube A and 0.035 g/dL in unopened Tube B. The paired difference was significant at P < 0.001.
Those matched-pair means should not be confused with the means for all initially positive tubes: 0.051 g/dL for 110 Tube A specimens and 0.035 g/dL for 104 Tube B specimens. The denominators answer different comparisons.
The paper’s actual volume categories matter
The table classified volumes as no more than 6 mL versus more than 6 mL. Although the narrative also describes these as approximately half-full categories, the operational 6 mL boundary should be retained when describing the results.
Previously opened tubes with no more than 6 mL lost a mean 0.080 g/dL, compared with 0.044 g/dL for higher-volume tubes. Unopened tubes lost means of 0.065 and 0.027 g/dL in the corresponding categories. Volume-group differences were significant at P < 0.001.
The authors proposed greater oxygen availability as an explanation, consistent with oxidation of ethanol. They did not directly measure the amount lost by oxidation versus every other possible mechanism in each tube.
Some initially positive tubes became negative
Six of 110 initially positive Tube A specimens and three of 104 initially positive Tube B specimens were negative after storage. Eight of these nine tubes were in the lower-volume category. Thus a much later negative result did not necessarily establish that the original specimen contained no ethanol.
Seven initially negative cases remained negative. That observation does not prove that microbial ethanol formation is impossible in every forensic specimen, particularly postmortem blood under different conditions.
Analytical controls addressed another source of difference
The original laboratory used dual-column headspace GC–FID. The second used headspace GC with simultaneous FID and mass-spectrometric detection, with FID quantitation. Its reported detection and quantification limits were 0.005 and 0.010 g/dL, and replicate CV was below 3.1%. Shared standard lots showed no significant difference at the study’s stated 99.9% confidence criterion.
That comparison strengthened the storage interpretation, but did not make the methods, storage durations and opening histories identical. No universal numerical add-back was validated.
Application in death investigations
For an archived specimen collected before death, record its fill volume, opening history, preservatives, storage and method before comparing results. Do not transfer these antemortem loss figures directly to autopsy blood, where additional formation and decomposition processes may operate. See the contrasting serial increase in a preserved autopsy specimen. Neither a stored concentration nor its change alone establishes impairment or cause of death.
Primary source
Tiscione NB, Vacha RE, Alford I, Yeatman DT, Shan X. Long-Term Blood Alcohol Stability in Forensic Antemortem Whole Blood Samples. Journal of Analytical Toxicology. 2015;39:419–425. doi:10.1093/jat/bkv037.
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