Lethal Carbon Monoxide Generated from Small Internal Combustion Engines.

Fuel-burning small engines have the potential to emit dangerous and potentially lethal concentrations of carbon monoxide when used in poorly ventilated environments. The North Carolina Office of the Chief Medical Examiner investigated seven cases from 2013 - 2020 involving lethal carbon monoxide from small internal combustion engines. Evaluation of percent carboxyhemoglobin saturation was determined in these case studies as ratios of carboxyhemoglobin to reduced hemoglobin, using HP 8453 and Agilent 8454 UV-Visible Spectrophotometers (Agilent Technologies, Santa Clara, CA). Sources of carbon monoxide included a pressure washer, a propane-powered forklift, an inboard engine boat, a motorcycle, propane and kerosene heaters, and home-use generators. It was demonstrated during one death investigation that the Dräger X-am 2000 electrochemical gas monitor often used by first responders, falsely reacted to acetylene gas, initially misleading investigators to the source of the carbon monoxide. Educating first responders about not only the hazards of these unexpected carbon monoxide sources, but the limitations of their equipment, is a valuable goal of disseminating complete medical examiner case information. The details of these cases will educate first responders, the forensic science community, and public health leaders on potential small engine sources of carbon monoxide in death investigations, responder safety, and the limitations of portable air quality monitoring equipment during death investigation.

Evaluation of Pretreatment and Extraction Parameters for the Analysis of Fentanyl in Hair Using Statistical Design of Experiments (DoE).

Optimal methods for hair analysis are often debated. Previous work in this laboratory demonstrated that the statistical technique known as Design of Experiments (DoE) is useful for such optimization. DoE evaluates both the individual roles and the combinatorial associations among multiple independent variables (i.e., hair pretreatment parameters) and a dependent variable (i.e., drug recovery from hair). In this study, hair externally contaminated with fentanyl underwent decontamination with combinations of parameters based on a 24 fractional factorial block design DoE matrix. The parameters of interest included aqueous wash solvent (1% sodium dodecyl sulfate (SDS) or water), organic wash solvent (dichloromethane or methanol), number of consecutive washes (one or three), sequence of washes (aqueous first or organic first) and wash time (30 s or 30 min). The optimal method for decontaminating fentanyl from the hair surface was found to be one 30-min wash with dichloromethane followed by one 30-min wash with water. Pretreatment parameters were optimized with a 23 full factorial DoE matrix using authentic hair reference material (HRM), which consisted of pooled drug user hair diluted to a known concentration of fentanyl with drug-free hair. The factors of interest were extraction solvent/sample weight ratio (12.5 or 25 µL/mg), hair particle size (pulverized or 1 mm segments) and extraction time (2 or 24 h). The most effective pretreatment method for fentanyl consisted of pulverizing the hair prior to a 2-h extraction in a 25 µL/mg extraction solvent volume/sample weight ratio. Finally, using the optimized pretreatment methods, fentanyl containing authentic HRM was extracted using aqueous base, solvent and enzymatic hair extraction methods, where it was determined that the aqueous base technique was most effective for recovery of fentanyl. These experiments further demonstrate the value of DoE and authentic HRM in method development for forensic hair analysis.

Evaluation of extraction parameters in authentic hair reference material using statistical design of experiments.

Optimal methods for forensic hair analysis are often debated, especially regarding extraction parameters that include incubation time, temperature, and size of extracted hair particles. To assess hair pretreatment parameters for analysis of drugs of abuse, the statistical technique known as Design of Experiments (DoE) is useful. DoE evaluates both the individual roles and the combinatorial associations between multiple variables and overall drug extraction efficiency. Previous reports have focused on incorporated hair reference material (HRM), which is prepared in the lab at a specified drug concentration. In contrast, authentic HRM, which is prepared by diluting hair from drug users with blank hair to achieve specific drug concentrations, is an effective matrix for standardization of forensic hair testing, since the drug is incorporated into the hair matrix via uptake from systemic distribution. In the present study, extraction parameters for authentic HRM samples containing multiple drugs (diazepam, alprazolam, cocaine, methamphetamine, oxycodone, hydrocodone, and morphine) and metabolites (nordiazepam, cocaethylene, norcocaine, hydroxycocaine, and 6-monoacetylmorphine) were optimized based on recovery using a 23 full factorial DoE matrix. The factors evaluated included extraction solvent volume/sample weight ratio (12.5 or 25 µL/mg), particle size (pulverized or cut into 1 mm snippets), and extraction time (2 or 24 h) using solvent swelling. DoE analysis revealed significant differences in the optimal combinations of extraction parameters for maximum recovery. However, for the majority of drugs and metabolites, the most effective extraction method consisted of pulverizing hair prior to a 2-h extraction with a 12.5 µL/mg extraction solvent volume/sample weight ratio.