Sampling procedures cannabis

Sample preconcentration was performed by means of an automated on-line SPE sample processor Prospekt-2 (Spark Holland, Emmen, The Netherlands). Oasis HLB cartridges (Waters, Barcelona, Spain) were used to preconcentrate cannabi-noids present in the water samples whereas isolation of the rest of the compounds was done in PLRPs cartridges (Spark Holland). Before extraction, influent samples were diluted with HPLC water (1 9, v/v) to reduce matrix interferences and to fit some analyte concentrations, e.g., cocaine (CO) and benzoylecgonine (BE), within the linear calibration range. A sample volume of 5 mL was spiked with the internal standard mixture (at 20 ng/L) in order to correct for potential losses during the analytical procedure, as well as for matrix effects. Elution of the analytes to the LC system was done with the chromatographic mobile phase. 

THC and its metabolites can be detected in plasma or urine samples only within a few hours to days after cannabis intake, which was documented by numerous extraction procedures. - At the opposite, hair appears to be an interesting substrate for the investigation of chronic exposure. ... 

Improved chromatographic techniques can vastly simplify hormone measurements even with more conventional detectors, such as the electron-capture, or even the flame-ionization detector. Wehner and Handke [285] used a very simple sample purification procedure with high recovery of plasma progesterone and its good quantitation as a 3,20-di-O-pentafluorobenzyloxime derivative at picogram concentrations. Measurements of 18-hydroxycorticosterone in human peripheral blood as a heptafluorobutyrate were performed by Wilson et al. [286]. Levels of testosterone, estrone and estradiol in male rat plasma were described by Maskarinec et al. [287,288] in relation to treatment with d -tetrahydrocannabinol and cannabis extracts heptafluorobutyryl derivatives were used for the electron capture detection. 

The sample preparation procedures described above can be used for the majority of drugs of abuse. Exceptions include cannabis, LSD and one or two others. A special preparation technique is used to determine these substances, but this is not discussed further here. 

There are numerons reports for the gas chromatographic determination of THC and its metabolites, ll-nor-A-9-tetrahydrocannibinol-9-carboxylic acid (THC-COOH) and ll-hydroxy-A-9-tetrahydrocannibinol (11-OH-THC) in urine and blood. THC is not normally found in urine, so it must be determined in blood at levels around 2-4 ng/mL. The TMS derivative is the most widely used derivati-zation procedure with GCMS for the determination of cannabinoids. In addition to the obvious advantages of derivatizing the THC metabolites, the acidic constituents of cannabis mnst be derivatized because they can easily decarboxylate above 80°C. Almost aU gas chromatographic procedures today use fused-silica capillary columns for this analysis. Determination of THC in blood is routinely done in forensic toxicological samples, and the detection and quantification of the two THC metabolites in mine is a routine procedure for proof of cannabis use in workplace testing. Several of the procedures used for this type of analysis are listed in Table 16.9. 

The purpose of sample preparation procedure(s) is to isolate the compounds of interest (THC and its meubolites) from the biological matrix and, if necessary, to concentrate the analytes to facilitate detection. Either LLE or SPE can be used for extracting cannabi-noids from biological matrices. Below are detailed the chosen LLE. 

THC-COOH, as the main metabolite of THC in urine, can be detected for many days after the last consumption of cannabis products. The THC-COOH concentration depends not only on the amount of drugs used, but also on the THC-content of the consumed cannabis product. Measurements with the method described above have shown that none of the commonly prescribed or OTC drugs interfered with the quantification of THC-carbonic acid in urine samples. This is due to the effective Extrelut extraction procedure. In addition. 

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