DFS Toxicology Subcommittee approves four validation plans for novel substances and methods

The Department of Forensic Science Toxicology Subcommittee voted to approve four laboratory validation plans during a virtual meeting where members reviewed technical details and testing thresholds for each protocol.

The committee approved: (1) adding selected novel psychoactive substances (NPS) into the existing amphetamines, phentermine and designer-stimulants LC–MS/MS quantitation and confirmation method; (2) validating volatile compound quantitation and confirmation by headspace, dual-column GC–FID (an NIJ grant project testing hydrogen carrier gas and multiple vial/dilution configurations); (3) using a circulating bath to freeze samples during the liquid–liquid extraction for the amphetamines/phentermine/designer-stimulants method; and (4) adding seven novel benzodiazepines to the existing benzodiazepine liquid–liquid extraction method.

Why it matters: The approvals authorize laboratory experiments and full validations that could expand the forensic toxicology laboratory’s ability to detect newer synthetic stimulants and benzodiazepines and refine procedures for volatile compounds. Committee members discussed limits of detection, matrix effects and stability concerns that will shape final reporting limits and method parameters.

Overview of plans and committee discussion

Novel psychoactive substances (NPS) Laboratory staff presented a validation plan to incorporate research chemicals and newly available certified reference materials and internal standards into the existing amphetamine/phentermine/designer-stimulant LC–MS/MS quantitation method. The presenter said the lab will use the same liquid–liquid extraction already validated for amphetamines but will adapt its instrumental acquisition from the lab’s existing NPS method. The presenter noted clonazolam was already added to another method and mitragynine will be validated separately.

Committee questions focused on sensitivity and detection limits. The lab described target concentrations evaluated at 0.05 mg/L and 0.025 mg/L and said the decision point is the ability to reliably detect roughly 5 nanograms per milliliter (0.005 mg/L); if the 0.005 mg/L level fails to meet a 95% detection threshold for a given compound, the lab will reassess the limit of detection for that compound. The committee also directed the lab to increase the number of matrix sources used to assess limits (see Votes at a glance).

Volatiles by headspace GC–FID (NIJ grant) Staff described an NIJ research grant project that will validate analysis of volatile compounds including acetone, ethanol, isopropanol and methanol. The protocol evaluates hydrogen as the carrier gas and compares four vial/dilution configurations (1:10 and 1:5 dilutions with 10 mL and 20 mL vials). The lab said it will run full validations for each configuration and produce validation summaries for the four approaches.

Committee members asked about vial material; the presenter confirmed glass vials will be used. No substantive objections were raised.

Circulating bath for amphetamines extraction The lab proposed using a circulating bath at −25 °C to freeze the bottom layer after centrifugation so technicians can pour off the supernatant instead of performing a manual pipette transfer. The change is limited to that transfer step; the lab said it will evaluate validation parameters that could be affected by freezing, and increase bias-and-precision matrix sources from one to three per matrix type at the committee’s suggestion. Staff noted some target analytes (bupropion, cited as an example) have demonstrated stability issues across multi-day pooled-sample testing, and the lab may move to fresh daily spikes for pooled bias/precision testing if instability persists.

Seven novel benzodiazepines Northern toxicology section staff presented a full validation plan to add seven benzodiazepines to the existing benzodiazepine liquid–liquid extraction method. The plan includes a brief cross-reactivity check against the laboratory’s existing immunoassay benzodiazepine screening kit for benchmarking; staff clarified this is not an immunoassay validation but an informational comparison.

Votes at a glance - Addition of novel psychoactive substances to amphetamine/phentermine/designer-stimulants LC–MS/MS method — Motion to proceed approved; mover: Miss Randall; second: not specified in record; no opposition recorded. - Validation of volatiles (headspace, dual-column GC–FID) — Motion to proceed approved; mover: Mr. Beatty; second: Mr. Myers; no opposition recorded. - Use of circulating bath for amphetamines extraction (modification approved) — Motion to proceed approved with modification to increase bias-and-precision matrix sources from 1 to 3 per matrix type; mover and second not specified in record; no opposition recorded. - Addition of seven novel benzodiazepines to benzodiazepine method — Motion to proceed approved; mover: Mr. Myers; second: not specified; no opposition recorded.

Distinct decisions versus discussion Committee members separated discussion points (sensitivity targets, matrix sources, stability of pooled samples) from formal action. The circulating-bath plan was approved with the explicit modification (increase bias-and-precision matrix sources to three per matrix type); the NPS plan and benzodiazepine additions were approved to proceed without recorded amendments beyond technical clarifications. Multiple members emphasized that limits of detection should be set by operational need and method performance, not by aspirational targets: as one member put it, “Set your what you need, not what you think you can do.”

What’s next The laboratory will carry out the experiments and draft validation summaries and updated method documents for each approved plan. Where a modification was made (circulating bath), staff confirmed they will implement the change to bias-and-precision matrix sourcing in the validation protocol. No public comments were recorded and the meeting adjourned after the approvals.