What is LC-MS/MS in drug testing?
Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) is the gold standard for confirmatory drug test analysis. Here we explain the method and what it means for legal certainty.
LC-MS/MS — Liquid Chromatography–Tandem Mass Spectrometry — is the analytical method that identifies substances specifically and quantitatively in drug tests. The method is the gold standard for confirmatory drug test analysis, and it is these results that hold up legally in work environment cases and disputes.
What does LC-MS/MS mean?
- LC (Liquid Chromatography): the sample is diluted in a solution that passes through a column where different substances are separated based on their chemical structure.
- MS/MS (Tandem Mass Spectrometry): the separated substances are fragmented and identified with high precision in two steps, giving a specific "fingerprint" signature for each substance.
Why is LC-MS/MS the gold standard?
Specificity
Rapid tests and initial screening rely on antibody binding, which can give false positive results due to cross-reactions. LC-MS/MS identifies the substance directly — no cross-reactions are possible.
Sensitivity
The method detects substances at extremely low concentrations (ng/mL). This means longer detection windows and greater reliability.
Quantification
LC-MS/MS measures not only presence but also concentration. Crucial for medical reviews and litigation.
Legal robustness
The Swedish Labour Court (Arbetsdomstolen) accepts LC-MS/MS confirmation as legally sound. A rapid test without confirmation is not a sufficient basis for action.
When is LC-MS/MS used?
- In all confirmatory analyses of positive rapid tests before reporting
- When investigating positive drug tests in the workplace
- In medical reviews and litigation
- In hair tests (where the method is required to detect substances at all)
- In the analysis of new psychoactive substances (NPS)
- In quantitative blood analysis
GC-MS vs LC-MS/MS
- GC-MS: Suitable for volatile substances. Requires derivatisation of many substances.
- LC-MS/MS: Suitable for a broader group of substances, including those that are difficult to handle in the gas phase. Requires less sample preparation.
Both are accredited methods that hold up legally. Provsvaret's partner labs use both depending on the substance and context.
What does it mean for employers?
When you engage Provsvaret, LC-MS/MS confirmation is included as standard for all positive rapid tests:
- Specific substance identification (not just "amphetamine", but amphetamine vs methamphetamine)
- Quantified concentration where needed
- Legal certainty in any Labour Court proceedings
- Complemented by MRO review for medical explanations
Accreditation
For an LC-MS/MS analysis to hold up legally, the lab must be accredited to ISO 15189 or equivalent. Provsvaret's partner labs are accredited, with good laboratory practice (GLP) and regular quality controls.
In summary
LC-MS/MS is what separates a legally robust drug test result from an uncertain rapid test. When evaluating providers, ask whether confirmatory analyses are carried out with LC-MS/MS in an accredited lab. Provsvaret delivers this as standard.
Read more about the entire chain of custody or our laboratory analysis. Get in touch for a review.
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