Confirmatory Technique
Definition
An instrumental method capable of identifying a specific molecule with sufficient selectivity to be admissible in court. The accepted gold standards are GC-MS and LC-MS/MS for organics, ICP-MS for metals, and FTIR or Raman for solid-state materials such as paints, polymers and explosives.
- For organics
- GC-MS, LC-MS/MS
- For metals
- ICP-MS
- For solids
- FTIR, Raman spectroscopy
- Requirement
- Sufficient selectivity for court admissibility
Common questions
Why is mass spectrometry treated as a gold standard for confirmatory identification?+
Mass spectrometry separates and weighs molecular fragments, producing a spectrum specific enough to distinguish closely related compounds that other methods might confuse. This selectivity is why GC-MS and LC-MS/MS results are widely accepted for identification testimony rather than screening alone.
Can a confirmatory technique still produce a wrong identification?+
Yes, through instrument miscalibration, library mismatch, sample contamination, or interpretation error by the analyst. A confirmatory technique reduces the risk of a false identification compared to a presumptive test, but it does not eliminate the need for proper method validation and quality control.
Related terms
- Hyphenated Technique
- A single workflow that couples a separation method to a spectroscopic detector, so a complex mixture is resolved and each component identified...
- Instrumental Technique
- An analytical method that uses an instrument to detect, identify or quantitate an analyte, distinguished from classical wet-chemistry methods such as titration,...
- 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...
- Presumptive Test
- A fast, low-cost, class-specific screen used to triage a caseload before instrumental work begins. Examples are Marquis reagent for opioids and amphetamines,...
- Sample Preparation
- The set of steps between the sealed evidence container and the instrument autosampler vial: extraction, clean-up, concentration, derivatisation, dilution, internal standard addition....