LC-MS
Definition
Liquid chromatography-mass spectrometry: the confirmatory analytical method for pesticide residues in biological matrices. Separates compounds by chromatography, then identifies them by mass-to-charge ratio. Highly sensitive and specific; court-admissible.
- Full name
- Liquid chromatography-mass spectrometry
- Role
- Confirmatory test for pesticide residues
- Matrix
- Biological samples, e.g. blood, tissue
- Key traits
- High sensitivity and specificity
Common questions
How does LC-MS differ from an initial screening test?+
Screening assays such as immunoassays flag that a class of compound may be present but can cross-react with related substances. LC-MS separates and identifies the exact compound by mass, so it is used to confirm a positive screen before a result is reported as evidence.
Why is LC-MS preferred over gas chromatography for some pesticides?+
Many modern pesticides are polar, non-volatile, or heat-sensitive and would decompose or fail to vaporise in a GC injector. Liquid chromatography separates these compounds without heating them, so LC-MS can analyse a wider range of pesticide classes intact.
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