In July of 2016, carfentanil (CF) emerged in Northeast Ohio resulting in over 25 deaths within a 30-day period. A total of 125 deaths have occurred in Summit County and Cuyahoga County has reported 40 deaths, relating to the presence of CF either alone, or in combinations with heroin and fentanyl. Prior to this surge in CF cases, positive fentanyl enzyme-linked immunosorbent assay (ELISA) screening results were increasing in number. Many were negative for fentanyl confirmation by gas chromatography-mass spectrometry. Fentanyl analogs such as CF, acetyl fentanyl (AF), 2-furanyl fentanyl (2-Fu-F) and 3-methylfentanyl (3-MF) may be present in these cases. Some fentanyl analogs like CF and 3-MF do not cross-react with the Immunalysis ELISA fentanyl assay. With the emergence of potent synthetic fentanyl analogs, questions arose as to how to interpret their very low concentrations or absence in the blood in relation to cause of death. Driving under the influence of drugs (DUID) blood specimens had also tested positive for CF by reference laboratories. A liquid chromatography-tandem mass spectrometry method was developed to identify and quantify fentanyl, norfentanyl (NF) and four analogs: AF, 2-Fu-F, 3-MF and CF. The method has been utilized to quantify these fentanyl analogs in blood and vitreous humor in authentic antemortem and postmortem cases. Calibration curves were established between 0.10-4.0 ng/mL (NF, AF, 3-MF, 2-Fu-F and CF) and 1.0-40 ng/mL for fentanyl. In total, 98 postmortem cases analyzed produced the following blood concentration ranges: CF (0.11-0.88 ng/mL), 3-MF (0.15-1.7 ng/mL), 2-Fu-F (0.15-0.30 ng/mL), AF (0.14-0.16 ng/mL), fentanyl (1.1-15 ng/mL) and NF (0.10-3.7 ng/mL). Only CF, fentanyl and NF were detected in a statistically significant subset DUID population of 26 cases producing concentration ranges between 0.11 and 0.47 ng/mL, 1.0 and 9.8 ng/mL, and 0.11 and 3.5 ng/mL, respectively.

Hundreds of synthetic substances have been introduced into the illicit drug market over the last ten years, but none of these drugs has had as poisonous a consequence as the emergence of the synthetic fentanyl analogs. Initially, pharmaceutical grade or illicit fentanyl was mixed with heroin, allegedly to boost the potency of the heroin. Then, the amounts of fentanyl spiked gradually increased until the proportion of fentanyl was greater than the proportion of heroin. Ultimately, many overdose cases began consisting of only fentanyl. The emergence of numerous synthetic fentanyl analogs, including acetylfentanyl, butyrylfentanyl, acrylfentanyl, furanylfentanyl and β-hydroxythiofentanyl, which are manufactured in China, were made available to the illicit drug traffickers over the Internet. In July of 2016, the most potent commercially available opioid, carfentanil, started appearing in illicit drug submissions and medical examiner death investigation cases in Northeast Ohio. Postmortem femoral blood carfentanil concentrations are in the picogram per milliliter (pg/mL) range, which is extremely low, and tests the limits of detection for most analytical forensic toxicology laboratories. The interpretation of these low carfentanil blood concentrations in antemortem and postmortem specimens is made difficult due to the overlap in the concentrations between these specimen types. The presence of these powerful synthetic fentanyl analogs presents a challenge to forensic toxicology laboratories preparing to analyze for these substances.

The first generation of this Microsoft (MS) Excel (Redmond, WA, USA) tool for method validation, EZSTATSG1, was designed for methods utilizing only linear calibration curves requiring seven calibration levels, and quadratic calibration models were not supported. This significantly improved version, EZSTATSG2, includes all of the features of the original template such as weighted linear calibration models, bias and precision data, dilution integrity and ion suppression. New features in this version include flexible five-, six- or seven-point calibration curves, six weighted quadratic calibration models, standardized residuals by use of frequency plots overlaid with the normal distribution function along with five-number summary data and processed sample stability. The implementation of Visual Basic for Applications in Excel UserForms prevents accidental alteration of existing formulas and also ensures that pertinent cells are relocked every time a file is reopened. The quadratic models feature the 95% confidence intervals for checking the significance of the second order term and are fully-characterized by providing the equations for the axis of symmetry, directrix, and coordinates for vertex and focus. Example data of α-hydroxymidazolam demonstrates that the quadratic calibration curves fit the data more adequately than the linear models for this method. This second-generation tool summarizes all of the validation parameters of a method for both linear and quadratic calibration models. Models with the lower average sum of relative errors and higher R2 values are color coded green, indicating the likelihood of a better fitting model. Like the EZSTATSG1, the redesigned EZSTATSG2.xltm MS Excel self-actuating validation tool and a completed PDF example are available to the scientific community for download as Supplementary data. Updates to the template can be found at https://www.EZSTATS4validation.com.

Bioanalytical methods developed in accredited forensic toxicology laboratories need to be validated according to the ISO/IEC 17025 standards to demonstrate that a method is fit for the intended use. The evaluation of the validation data can be a time-consuming process without a streamlined procedure on a common platform or the aid of a specific software package. The objective of this work was to develop a Microsoft (MS) Excel (Redmond, WA, USA) template, which can rapidly generate all the required numerical and statistical validation results of a quantitative bioanalytical assay with minimal data entry, and to provide documented traceability of the validation data directly to the instrument raw data. Evaluation of method validation data can be done easily by taking advantage of the power of statistical tools available within Excel. The three key features of the template were the development of six pertinent weighted linear calibration models, the variance in instrument response as a function of concentration, and integrated one-way ANalysis-Of-VAriance (ANOVA) tables. None of the ANOVA tables in this template need to be recreated whenever the source data changes which is a major time savings when a method contains several dozen analytes. It takes approximately 60 minutes per analyte to enter all the instrument raw data manually from the chromatograms. The final method validation results are summarized in a two-page Validation Summary Report. Whereas, the associated data tables and graphs are presented in an additional 65 pages of digital information which can be saved for electronic records using portable document format (PDF). This EZSTATSG1.xltm customized MS Excel method validation template and a completed PDF example are being provided as downloadable files in the Supplementary data link to offer an option to the scientific community for expediting the evaluation of validation data.

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