Practically, total recoveries were found for all compounds. ( 2) applied spiking of the questioned compounds at different concentration levels for the determination of extraction recovery of paracetamol, caffeine, heroin, morphine and its other derivatives from black market heroin using the mixture of methanol and chloroform (1:9, v/v) as extraction solvent. For recoveries, 92–95% were measured depending on the matrices. Ciolino ( 1) applied spiking for the determination of extraction recovery of 32 synthetic cannabinoids from different plant matrices using acetonitrile as extraction solvent. Spiking is suitable in these cases if the concentrations are in the linear range of the distribution equilibrium, which should be controlled before the application. In these cases, if extraction solvent does not totally dissolve the whole preparation, the distribution of the target compound between the solvent and non-soluble matrix residue determines the extraction recovery. Example for the previous one is an herbal preparation impregnated with a synthetic cannabinoid and for the second one is black market heroin where the heroin is being present, for example, in the mixture of lactose, paracetamol and caffeine. The object of this study was the determination of systematic error of the quasi-counter current liquid–solid extraction, which has contribution to the resulting total error of the quantification.įor the determination of systematic error of extraction, one of the widely applied procedures is spiking, which is well applicable in those cases where target compounds of the extraction are present on the surface of the sample matrix or physically mixed with it. The systematic error can be taken into correction if its rate is known. The random error of the whole procedure can be calculated from those of the individual sub-steps according to the quadratic error propagation law. All sub-steps of the whole procedure, including sampling, homogenization, weighing, extraction, filtration, dilution, chromatographic separation, detection, etc., have effect on the quality of the quantitative results. Quantification in most analytical procedures is based on chromatographic separation. Serving reliable results is important because the results have often significant effect on the rigor of the punishment to be imposed. Quantification of controlled substances in natural materials, such as plants and mushrooms, is an important task of the forensic drug analysis. For mushrooms, it could be stated that preliminary treatment of mushrooms with liquid nitrogen significantly increases the extractability of psilocin. The calculated component transport constants predict the expectable velocity of the extraction, i.e., the higher the component transport constant is, the higher the extraction velocity is. The mentioned model was found to be suitable for the determination of extraction time needed to reach a predefined extraction recovery for quasi-counter current liquid–solid extractions, as well, which allows the elimination of systematic error caused by the non-extracted part. According to this model, quasi-counter current liquid–solid extractions were designed by calculation of component transport constants for extractions of psilocin from hallucinogenic mushroom, mescaline from hallucinogenic cactus, harmine from tropical lyan and salvinorin A from hallucinogenic sage. The mentioned model is applicable for dynamic SFE whose implementation is analogous to liquid–solid extraction in quasi-counter current mode. The aim of this work was to investigate the applicability of a mathematical model developed for the description of supercritical fluid extraction (SFE) of cannabinoids from marijuana and hashish for liquid extraction of other substances.