Sample Preparation and Analysis of Real Samples

Before starting the sample preparation, it is necessary to know the concentration/time curve of the compound in blood. The deamination time depends on the compound and in some cases also on the abuse behavior of the person. It is very important to know the kinetics. Cocaine is metabolized to 

The sample preparation is carried out as described in Chapter 7. The derivatization is performed with 70 pi PFP alcohol and 100 pi PFP anhydride. If PFP is used for the derivatization it is necessary to use water-free ethyl acetate to dissolve the residue. 

For the determination of THC-COOH and also A9-THC, a C-18 cartridge preconditioned with methanol can be used, and the elution is done with acetonitrile. We normally use the complete sample preparation procedure for the determination of all compounds that could be present. 

The results and the sensitivity are much better when methanolic standards are used for the calibration curve, because then no matrix effects are taken into consideration. Using SPE as the sample preparation method, a detection limit for 

Another example of the quantitative determination of a drug is provided by LSD. Because of the very high retention index (3595) of the LSD-TMS derivative, chromatography is not easy. Well-deactivated silylated inserts are recommended. The extracts from a human specimen should be free of matrix (reextraction). For the derivatization, the extremely dry residue is taken up in BSTFA/TMCS (Fluka 15238) and derivatized for 20 min at 70°C. Instead of pure BSTFA/TMSC, a 30-50% solution in a dry solvent such as acetic acid, diethyl ether or dioxan can be used. 

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