SUBJECT AREA · 18 GUIDES
Quality & Validation
The controls, performance studies, documentation, and review practices behind reliable testing.
Calibration in Forensic Toxicology
Calibration relates instrument response to known reference concentrations. A reported number is supportable only within a demonstrated and accepted calibration model.
LOD and LOQ in Toxicology
The limit of detection concerns reliable detection; the limit of quantitation concerns measurement with acceptable performance. They answer different laboratory questions.
Carryover and Contamination
Carryover is signal transferred from a preceding sample or injection. Contamination can occur at collection, preparation, or analysis and requires source-specific investigation.
Proficiency Testing
Proficiency testing compares laboratory performance using samples with assigned or consensus outcomes. It is one component of competence, not a substitute for case-specific review.
Reference Materials in Toxicology
Reference materials connect identification and measurement to known compounds and concentrations. Source, purity, uncertainty, storage, and expiration all matter.
Dilution Integrity
Dilution integrity shows that high-concentration specimens can be diluted and still measured accurately within the validated range.
Measurement Uncertainty
Measurement uncertainty describes the dispersion reasonably associated with a measured value. It communicates that a laboratory result is an estimate, not an exact point.
Quality Control in Toxicology
Quality-control samples monitor whether an analytical run performs as expected. They should challenge meaningful concentrations and be assessed before case results are accepted.
Method Validation in Forensic Toxicology
Validation provides documented evidence that a method is fit for its intended forensic purpose. Scope, matrix, analytes, range, and decision criteria should be explicit.
Accuracy and Precision
Accuracy concerns closeness to a reference value; precision concerns agreement among repeated measurements. A method needs both for defensible quantitation.
Calibration Verification
Calibration verification checks that an established relationship remains valid using independent or separately prepared material.
Toxicology Reporting Cutoffs
A reporting cutoff is an administrative or scientific decision threshold. It is not automatically the method's detection limit or a boundary between impairment and sobriety.
Blank Samples in Toxicology
Blanks help reveal contamination, carryover, endogenous response, or reagent background. Different blanks answer different questions.
Chain of Custody
Chain of custody documents possession and transfer of evidence. It supports identity and integrity but does not by itself establish analytical correctness.
Laboratory Accreditation
Accreditation assesses a laboratory against defined standards through external review. It is valuable system evidence, but each method, batch, and result still warrants review.
Method Transfer
A validated method may need verification when moved to a new instrument, location, staff, or workflow. Transfer evidence should match the extent of change.
Instrument Maintenance
Preventive maintenance, repairs, tuning, and performance checks help keep instruments fit for use. Case review should connect maintenance events to analytical sequences when relevant.
Toxicology Data Review
Technical review examines raw data, processing, calibration, controls, identification, calculations, and reporting. Administrative review alone is not equivalent.