Limit of Detection (LOD) and Quantitation (LOQ)
Definition
LOD is the lowest concentration at which the signal-to-noise ratio is 3:1; LOQ is where it is 10:1. LC-MS/MS LOQs for drugs in biological matrices typically sit between 0.1 and 1 ng/mL.
Related terms
- ATR (Attenuated Total Reflectance)
- An FTIR sampling mode in which the sample is pressed against a diamond or ZnSe crystal and the evanescent wave probes the...
- Beer-Lambert Law
- A = εbc. Absorbance equals molar absorptivity times path length times concentration. The linear relation between absorbance and concentration that makes UV-Vis...
- Electron Impact (EI) Ionisation
- A hard ionisation mode at 70 eV used in GC-MS that produces extensive, reproducible fragmentation. The fragmentation pattern is matched against libraries...
- Fingerprint Region
- The 1500 to 400 cm⁻¹ stretch of an infrared spectrum where bending and combination bands produce a pattern unique to a given...
- 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...
- MRM (Multiple Reaction Monitoring)
- A targeted MS/MS scan mode on a triple quadrupole that monitors specific precursor-to-product ion transitions, with two transitions per analyte (quantifier and...
Explained in
- Spectrometric Detection: UV-Vis, FTIR and Mass SpectrometryLOD is the lowest concentration at which the signal-to-noise ratio is 3:1; LOQ is where it is 10:1. LC-MS/MS LOQs for drugs in biological matrices typically si...