A Preliminary Investigation into Retrospective Calculation of In-Vivo Drug Concentrations in Dried Crime Scene Blood. Dwain C. Fuller*, Patricia Pisana, Veterans Affairs North Texas Health Care System, Dallas, TX, U.S.A. Why?.
Dwain C. Fuller*, Patricia Pisana, Veterans Affairs North Texas Health Care System, Dallas, TX, U.S.A.
Mean: g dried blood/mL liquid blood = 0.215± 0.025 g (0.161 - 0.259)
CV = 11.6 %
Prediction Uncertainty: approximately ± 23% with 95% confidence
Density: 1.052 ± 0.020 g/mL Present Study1.055 g/mL (Karch, Forensic Issues in Alcohol Testing, CRC Press, 2007)1.06 g/mL (Cutnell, et al. Physics, 4th edition, Wiley, 1998)1.025 – 1.125 g/mL (Benson, Katherine, MCAT Review, Emory University,1999)1.043 – 1.057 g/mL
(Hinghofer-Szalkay, et al., Continous Monitoring of blood volume changes in Humans, Journal of Applied Physiology, Vol 63, 1987)
79.6 ± 2.4 % g/g Present Study
76.9 – 82.0 % g/g 80.5 % g/g – Females 78.9 % g/g – Males
Lijnema, et al., Gravimetric determination of the water concentration in whole blood, plasma and erythrocytes and correlations with hematological and clinicochemical parameters. ClinicaChimicaActa, 214, 1993
*These values may reflect some breakdown of cocaine to EME
Because of expected lability of cocaine and its metabolites, their stability was determined by comparison to a freshly spiked liquid blood specimen using the original spiking solution stored at -80⁰C, rather than the original liquid blood specimen itself.
Benzoylecgonine is considerably more stable in dried blood at room temperature than is EME.
Isenschmid, Levine, Caplan. JAT, 13:250; 1989
Benzoylecgonine probably breaks down to ecgonine. Thus ecgonine would probably be an important target analyte to demonstrate cocaine use when analyzing dried blood.
Logan. JAT, 25:219; 2001
Skopp, Klingman, et al. Ther. Drug. Monit. 23:174; 2001
It may be possible to quantitate drugs in unpreserved dried blood obtained from a crime scene, convert the drug concentrations to their previous liquid blood equivalent, and accurately assess the uncertainty of this process.