Blood Cannabinoids

• Author: James G. Wigmore
• Pages: 37-45

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 2

Blood Cannabinoids

The concentrations of THC and other cannabinoids in the blood are

approximately , times less than that of alcohol. Hence, the meth-

ods used to analyze a lcohol, such as headspace gas chromatog raphy and

the breathalyzer, do not apply to this drug. Instead, blood ca nnabinoid

analysis requires more sensitive and sophisticated instruments, such as

gas chromatography-mass spectrometry (GC-MS) or liquid chromatog-

raphy-mass spectrometry (LC-MS) or even LC-MS-MS. Cannabinoid

concentrations dif‌fer in blood compared to serum/plasma as they are

bound to carrier proteins found in the serum/plasma portion of the

blood and not the red blood cells.

2.01 METHODS OF ANALYSIS

The analyses of THC and other ca nnabinoids are conducted by immuno-

assays (as a screen) and then conf‌irmed by laboratory-based ma ss spec-

trometers of one type or another. The f‌irst type of immunoassay was

RIA or radio-immunoassay (). Other immunoassay techniques

include ELISA (enzyme-linked immunosorbent assay), EMIT (enzyme-

multiplied immunoassay technique) or FPIA (f‌luorescence polarization

immunoa ssay).

Various types of mass spec trographic techniques are employed

for the conf‌irmation and quantif‌ication of the immunoassay screens

(-). An automated method has been described ().