Cocaine fast determination

FIGURE 21.3 Action of class I and II cocaine-displaceable aptamers The effect of cocaine-displaceable aptamers 1-14 and II-3 on carbamoylcholine (lOOpM)-induced stimulation of acetylcholine receptor activity in the absence (control) and presence of cocaine was determined in vitro by fast kinetic electrophysiology. Aptamer 1-14 (0.5 pM) inhibited receptor activity (left panel) aptamer II-3 (5 pM) does not inhibit receptor activity (middle panel) aptamer II-3 (3 pM) alleviates inhibition of receptor function by cocaine (150 pM) (right panel). Prediction of the secondary structure [26] revealed the localization of consensus motifs of class-I and -II aptamers in stem-loop regions (letters in boxes). These stem loops are believed to be necessary for aptamer action. The figure reveals the data published in references [18, 19, 74]. 

The importance of pharmacokinetics should not be underestimated. The effects of psychoactive drugs are determined not only by their pharmacodynamic mechanisms, but also by how much of the drug reaches the brain, and how fast it does so. A cardinal example of this involves the behavioral differences between chewing coca leaves, snorting cocaine... 

A different application of SPE which needs 100-200 pi of sample has recently been successfully applied to plasma. Micro SPE (pSPE) followed by HPLC-MS/ MS was used by Napoletano et al. [67] to determinate amphetamine, methamphet-amine, MDA, MDE, MDMA, cocaine, BEG, mescaline, ketamine, PCP, psilocy-bine in plasma. In this method 180 pi of plasma were submitted to slight PPT with 20 pi of methanol containing ISTD, 100 pi of supernatant were then collected and passed through C18 tips, adapted to automatic pipettes. Validation results showed pSPE allows to reduce matrix effect (<10 %) keeping satisfactory recoveries. pSPE represent a simple, fast and reliable procedure with extremely reduced solvent consumption it will be discussed in more detail below in its other applications. 

Leaf samples of various Erythroxylum species have been investigated for their cocaine content by a fast GC-MS method [29]. Amongst the 51 analyzed species, 28 had not been examined previously and cocaine was detected in 23 wild species. Cocaine content was less than 0.001 % for all wild species, except for Erythroxylum laetevirens in which a 10-fold higher concentration was determined. The qualitative... 

Fig. 12.3 Fast cocaine determination in coca leaves by GC according to Ilias et al. (adapted from [37]). (a) Schematic of the total analysis time, (b) Fast GC-FID chromatogram using a short 100 p,m i.d. column and a fast oven temperature programming.

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