Orthogonality (Analytical)
Definition
The requirement that two methods used in a drug identification measure genuinely different physical or chemical properties. Orthogonality ensures that the probability of a false positive in both methods simultaneously is the product of the individual false-positive probabilities, not merely the higher of the two. Two GC runs with the same stationary phase are not orthogonal; GC-MS and FTIR are orthogonal.
Related terms
- Category a Method
- An analytical method that provides the highest level of discriminating power in drug identification, generating structural or molecular fingerprint information. Category A...
- Category B Method
- An analytical method with intermediate discriminating power, measuring a characteristic but less structurally specific property. Includes UV-Vis spectroscopy, TLC, GC without MS,...
- ENFSI Drugs Working Group (DWG)
- European Network of Forensic Science Institutes Drugs Working Group. Publishes best-practice manuals for drug analysis aligned with SWGDRUG tiering principles, operates an...
- 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...
- 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...
- 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...
- Multiple Reaction Monitoring (MRM)
- An LC-MS/MS acquisition mode in which the first quadrupole (Q1) selects a precursor ion at a specific m/z, the second (Q2) fragments...
- NDPS Small Quantity / Commercial Quantity
- Quantity thresholds defined in the schedules to India's NDPS Act 1985 that determine the severity of criminal charge and applicable mandatory minimum...
- SWGDRUG
- Scientific Working Group for the Analysis of Seized Drugs, established in 1997 by the US DEA and the Office of National Drug...
Explained in
- SWGDRUG Identification Tiers and the UV / TLC / GC-MS / LC-MS/MS WorkflowThe requirement that two methods used in a drug identification measure genuinely different physical or chemical properties. Orthogonality ensures that the prob...