NIST SRM 612
Definition
National Institute of Standards and Technology Standard Reference Material 612 (Trace Elements in Glass); the primary calibration material for LA-ICP-MS glass comparison, providing certified concentrations for 61 elements in a soda-lime glass matrix.
- Full name
- Trace Elements in Glass
- Matrix
- Soda-lime glass
- Certified elements
- 61
- Primary use
- Calibration standard for LA-ICP-MS glass comparison
Common questions
Why is SRM 612 used even when the questioned glass is not soda-lime?+
Its certified concentrations across many trace elements let one external standard cover the elements measured in casework glass. Matrix differences between the NIST glass and the questioned glass are corrected using an internal standard element, typically calcium or silicon.
Is a matrix-matched standard ever preferred over SRM 612?+
For most casework glass types, no; SRM 612 is the accepted community standard for LA-ICP-MS glass comparison protocols, which is what allows results to be compared meaningfully across laboratories.
Related terms
- ASTM E1967
- The ASTM International standard for forensic glass RI measurement; specifies three acceptable methods (automated, semi-automated, manual), minimum precision of ±0.0001 RI units,...
- ASTM E2927
- Standard test method for the determination of trace elements in glass samples using LA-ICP-MS; specifies the element suite, calibration standards (NIST SRM...
- Bayesian Likelihood Ratio (LR)
- The statistical framework that evaluates glass-fragment evidence by comparing the probability of the observed fragment population assuming contact with the source glass...
- ENFSI ENG3-2013
- The ENFSI Glass Expert Working Group guideline for glass comparison casework; specifies the examination sequence, within-source variation requirements, statistical comparison framework, and...
- GRIM-3
- Glass Refractive Index Measurement, third-generation instrument by Foster + Freeman (UK); an automated phase-contrast hot-stage system that identifies the RI match point...
- Hotelling's T2
- The multivariate generalisation of the t-test used to compare mean element-concentration vectors between questioned and known glass populations; accounts for the full...
- LA-ICP-MS
- Laser ablation inductively coupled plasma mass spectrometry; a technique that fires a laser pulse at a sample surface, vaporises a tiny amount,...
- Mahalanobis Distance
- A multivariate distance measure that expresses the separation between two observations in units of the population standard deviation, accounting for covariance; used...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...
- Sequential Gate Design
- The casework workflow structure in which analytical methods are applied in order of increasing cost and complexity, with an exclusion possible at...
- Within-Source Variation
- The natural variation observed among multiple samples collected from a single source location. Used to estimate the probability of the observed difference...