Certified Reference Material (CRM)
Definition
A sample with one or more analyte concentrations established by an accredited body and traceable to a national metrology institute. NIST SRM 1577c bovine liver, NIST SRM 955c lead in caprine blood, Indian Pharmacopoeia reference standards from IPC Ghaziabad and Sigma certified solutions are the four classes most Indian forensic laboratories actually buy and use.
- Traceability basis
- SI units and national metrology institutes ensure certified values can be linked to international standards
- Key documentation
- Certificate includes property values, measurement uncertainty, traceability chain, and stability or expiry information
- Regulatory standard
- CRM definition and requirements are codified in ISO Guide 30:2015
Common questions
What makes a reference material certified?+
A certified reference material (CRM) has property values established by an accredited body with documented traceability back to SI units and a national metrology institute. It comes with a certificate stating the property value, its measurement uncertainty, and an expiry date. This chain of traceability is what lets forensic labs trust their results.
Why do forensic labs use CRMs instead of just any reference standard?+
CRMs ensure results are comparable across different labs and over time because they're characterized using metrologically valid procedures and accompanied by certified uncertainty values. A lab using the same CRM knows its measurements are anchored to the same baseline as every other lab using that material. This is essential for evidence that may be challenged in court.
What are examples of CRMs used in Indian forensic labs?+
Indian forensic toxicology benches commonly use NIST SRM 1577c bovine liver, NIST SRM 955c lead in caprine blood, Cerilliant single-analyte ampoules, UTAK whole-blood toxicology panels, and reference standards from the Indian Pharmacopoeia issued by IPC Ghaziabad and Sigma certified solutions.
Related terms
- Internal Standard (IS)
- A compound chemically near-identical to the analyte, often a deuterated isotopologue (d3-morphine, d5-EDDP, d5-alprazolam, pyrene-d10), spiked into every sample at a known...
- Measurement Uncertainty (MU)
- A quantified parameter associated with a result that characterises the dispersion of values reasonably attributable to the measurand. Estimated by the GUM...
- Bracketing Standards
- Calibration standards or quality control samples injected before, during and after a batch of case samples. They track instrument drift through the...
- Calibration Curve
- In RIA, a set of standards containing known concentrations of unlabelled analyte that are run alongside test samples. Bound radioactivity is measured...
- Extraction
- The first step in sample preparation. The analyte is pulled out of its original matrix (blood, urine, viscera, soil, paint chip) into...
- ISO 17034
- The international standard specifying general requirements for the competence of reference material producers; an ISO 17034-accredited producer has demonstrated the technical competence...
- ISO/IEC 17025:2017
- The international standard specifying general requirements for the competence of testing and calibration laboratories. Covers management (document control, non-conforming work, audits) and...
- Known (K) Sample
- A sample with documented, verified provenance used as the reference in a comparison. The origin of a K sample is not in...
- Limit of Detection (LOD)
- The lowest concentration of analyte that produces a signal reliably distinguishable from the instrument noise, conventionally three times the standard deviation of...
- Limit of Detection (LOD) and Limit of Quantitation (LOQ)
- LOD is the lowest concentration the instrument can reliably distinguish from blank, defined as three times the standard deviation of the blank...
- Limit of Quantification (LOQ)
- The smallest concentration that can be quantified with acceptable precision and accuracy, typically corresponding to a signal-to-noise ratio of 10:1 or an...
- Linearity
- The range of analyte concentrations over which an analytical method produces instrument responses that are proportional to concentration (the calibration curve is...
Explained in these topics
- ISO 17025 and Quality Management in Forensic LaboratoriesA reference material accompanied by a certificate that states one or more property values, their uncertainty and a documented chain of traceability to SI units...
- Reference Standards, Controls and Comparison LogicA material characterised by a metrologically traceable procedure, with certified property values and stated measurement uncertainties. Used to calibrate instru...
- Reference Standards, Certified Reference Materials and the Quantification BaselineA reference material characterised by a metrologically valid procedure, accompanied by a certificate providing the certified property value, its expanded uncer...
- Sample Preparation, Purification and Instrument CalibrationA sample with one or more analyte concentrations established by an accredited body and traceable to a national metrology institute. NIST SRM 1577c bovine liver...