The Contribution of Body Mass and Volume of Distribution to the Estimated Uncertainty Associated with the Widmark Equation.

The Widmark equation is used forensically for the determination of the amount of ethanol (alcohol) that may have been consumed and also to determine the blood alcohol concentration (BAC) of an individual at a specific time. It is important to be able to estimate the uncertainty associated with Widmark equations. To date, there has been no detailed determination of contribution to the final uncertainty of Widmark calculations of the volume of distribution of ethanol (Vd ), using anthropometric equations, or the contribution of an individual's body mass. Using published data, published literature, and freedom of information data, we determined that the variability (%CV) associated with Vd was ~10% (Watson et al. and Forrest anthropometric equations) and that the %CV associated with estimated body mass was ~15% compared to ~3% when body mass was directly measured. These data allow an estimation of the overall uncertainty of Widmark calculations using general error propagation. The estimated total uncertainty for BAC calculations increased from ~11% (volume consumed) and ~22% (BAC) to ~19% (volume consumed) and ~37% (BAC) when using measured body mass compared to estimated body mass. These results demonstrate that forensic practitioners should be mindful of the increase in estimated uncertainty in calculated Widmark equation results when estimated body mass is used rather than measured body mass. These data further improve the knowledge around the uncertainty of results calculated with the Widmark equation.

Society of Hair Testing guidelines for drug testing in hair.

The Society of Hair Testing (SoHT) Guidelines for Drug Testing in Hair provide laboratories with recommended best practice guidelines whether they are currently offering drug testing in hair, or plan to offer a hair testing service in the future. The guidelines include reference to recommended sample collection and storage procedures, through sample preparation, pre-treatment and analysis and the use of cut-offs.

Oxycodone-related fatalities in the west of Scotland.

The intent of this study was to review fatalities involving oxycodone in the west of Scotland using a liquid chromatography-electrospray ionization-tandem mass spectrometry method developed for the determination of oxycodone and N- and O-demethylated metabolites in unhydrolyzed postmortem specimens. Ten oxycodone positive postmortem cases were detected, and nine were drug-related fatalities. Five cases were attributed solely to oxycodone intoxication and four to polydrug intoxication. Although there was overlap between blood oxycodone levels in deaths attributed to oxycodone only and those due to polydrug intoxication, lower oxycodone levels (< 1 mg/L) were associated with polydrug intoxication when compared with cases due to oxycodone alone (> 1 mg/L). The role of the parent drug in oxycodone fatalities has been fully studied, but the role of oxycodone metabolites (noroxycodone and oxymorphone) was investigated in this report for the first time. Oxycodone was more commonly detected in blood, urine, and vitreous humor followed by noroxycodone. The ratio between oxycodone and its N-demethylated metabolite was evaluated and found to be useful in determining whether death occurred shortly after drug administration or if there was a significant delay. High parent/metabolite ratios were correlated with short survival times after ingestion. The median ratio of oxycodone/noroxycodone was 2.4 and ranged from 0.7 to 49. Oxycodone prescriptions have risen sharply in Scotland in recent years, and the identification of 10 oxycodone-related deaths in the past 18 months highlights the importance of including this drug in routine laboratory screening and confirmation procedures.

Determination of beta-hydroxybutyrate in blood and urine using gas chromatography- mass spectrometry.

Beta-hydroxybutyrate (BHB) is considered a potential biomarker for alcoholic ketoacidosis (AKA). A robust and sensitive method was developed and validated for the quantitative determination of BHB in postmortem blood and urine using deuterated gamma-hydroxybutyrate as an internal standard. Samples were analyzed by gas chromatography-mass spectrometry following liquid-liquid extraction and silyl derivatization. The limits of detection and lower limits of quantification in blood and urine were 2 and 7 mg/L and 2 and 6 mg/L, respectively. The interday and intraday precision was measured by coefficients of variation for blood and urine and ranged from 1.0 to 12.4% for quality control samples spiked at 50 and 300 mg/L. The linear range of 50-500 mg/L resulted in an average correlation of R(2) > 0.99, and the average extraction recoveries in blood and urine were >or= 82% and >or= 59%, respectively. BHB remains stable in blood spiked at a concentration of 300 mg/L for 15 days when stored within a refrigerator (2-5 degrees C). Postmortem blood and urine samples were analyzed using the validated method for cases where the deceased had a history of chronic alcohol abuse to establish the use of BHB as a potential marker of AKA.

Performance characteristics of the Cozart RapiScan Oral Fluid Drug Testing System for opiates in comparison to ELISA and GC/MS following controlled codeine administration.

Oral fluid is an interesting alternative matrix for drug testing in many environments, including law enforcement, workplace drug testing, and drug treatment facilities. Performance characteristics of the FDA-cleared, qualitative, Cozart RapiScan Opiate Oral Fluid Drug Testing System (Opiate Cozart RapiScan System or Opiate CRS) were compared to the semi-quantitative Cozart Microplate EIA Opiate Oral Fluid Kit (Opiate ELISA) and to gas chromatography/mass spectrometry (GC/MS). The following oral fluid opiate cutoffs were evaluated: the GC/MS limit of quantification (LOQ) of 2.5 mg/l; 15 microg/l currently used for oral fluid testing in the United Kingdom (UK); 30 microg/l (Opiate CRS cutoff); and 40 microg/l, the proposed Substance Abuse and Mental Health Services Administration (SAMHSA) cutoff. Subjects provided informed consent to participate in this IRB-approved research and resided on the closed research ward throughout the study. Three oral codeine doses of 60 mg/70 kg were administered over a 7-day period. After a 3-week break, subjects received three doses of 120 mg/70 kg within 7 days. Oral fluid specimens (N = 1273) were analyzed for codeine (COD), norcodeine (NCOD), morphine (MOR) and normorphine (NMOR) by GC/MS with an LOQ of 2.5 microg/l for all analytes. MOR and NMOR were not detected in any sample; 26.5% of the specimens were positive for COD and 13.7% for NCOD. Opiate CRS uses a preset, qualitative cutoff of 10 microg/l; this is equivalent to 30 microg/l in undiluted oral fluid as the oral fluid collection process involves a 1:3 dilution with buffer. Sensitivity, specificity, and efficiency of Opiate CRS compared to Opiate ELISA were 98.6, 98.1, and 98.2% at a 30 microg/l cutoff and 99.0, 96.2, and 96.6% at a 40 microg/l cutoff. Compared to the much lower GC/MS LOQ of 2.5 microg/l, sensitivity, specificity and efficiency were 66.8, 99.3 and 90.7%. Increasing the GC/MS cutoff to the current UK level yielded performance characteristics of 81.5% (sensitivity), 99.3% (specificity), and 95.4% (efficiency). Using a GC/MS cutoff identical to the preset Opiate CRS cutoff yielded sensitivity, specificity, and efficiency of 88.5, 99.2, and 97.5%, respectively. At the proposed SAMSHA confirmation cutoff of 40 microg/l, sensitivity increased with little change in specificity and efficiency (91.3% sensitivity, 98.9% specificity, and 97.5% efficiency). Oral fluid is a suitable matrix for detecting drugs of abuse. Opiate CRS, with a 30 microg/l cutoff, is sufficiently sensitive, specific and efficient for oral fluid opiate analysis, performing similarly to Opiate ELISA at the same cutoff, and having performance characteristics >91% when compared to GC/MS at the proposed SAMHSA cutoff.

Cozart RapiScan Oral Fluid Drug Testing System: an evaluation of sensitivity, specificity, and efficiency for cocaine detection compared with ELISA and GC-MS following controlled cocaine administration.

Oral fluid has become a widely accepted alternative matrix for drugs of abuse detection. Immunoassays have been developed for on-site testing of cocaine and metabolites in oral fluid. The performance of the Cozart RapiScan Oral Fluid Drug Testing System (CRS) was evaluated in comparison with Cozart Microplate Enzyme Immunoassay Cocaine Oral Fluid Kit (COC ELISA) and gas chromatography-mass spectrometry (GC-MS) at several screening and confirmation cutoffs, including those proposed by SAMHSA and those currently in use in the U.K. Oral fluid samples (n = 1271) were collected prior to and following controlled clinical cocaine administration. CRS provides a qualitative screen at a preset cutoff of 30 microg/L. Sensitivity, specificity, and efficiency for CRS (30 microg/L) as compared with COC ELISA with a cutoff of 30 microg/L were 92.1%, 91.8%, and 92.0%. The comparison of CRS (30 microg/L) with the 8-mg/L proposed SAMHSA confirmation cutoffs for cocaine and/or benzoylecgonine exhibited a sensitivity of 82.7%, a specificity of 94.5%, and an efficiency of 87.6%. For this study, an alternative CRS cutoff of 20 microg/L was also evaluated. Performance characteristics of CRS (20 microg/L) at the proposed SAMHSA confirmation cutoffs were 89.9%, 89.7%, and 89.8%, respectively. At cutoffs in use in the U.K., 30- micro g/L CRS screen and 15- microg/L GC-MS cutoffs for cocaine, benzoylecgonine, and/or ecgonine methyl ester sensitivity, specificity, and efficiency were 89.4%, 92.2%, and 90.7%, respectively. Cozart RapiScan had performance similar to the COC ELISA assay for the detection of cocaine exposure and suitable sensitivity and specificity at the proposed SAMHSA cutoffs.