Determination of amphetamine by HPLC after acetylation.

An analytical procedure has been developed for the HPLC determination of amphetamine by off-line pre-column derivatization. The proposed procedure consists of sample preparation by acetylation of amphetamine with acetic anhydride and a subsequent reversed-phase HPLC separation on an octadecyl silica stationary phase with salt-free mobile phase (tetrahydrofuran, acetonitrile, 0.1% triethylamine in water, 15:15:70 v/v) applying UV-detection. The applicability of the elaborated procedure is demonstrated with results obtained by analysis of real samples seized in the Hungarian black market.

Supercritical carbon dioxide extraction and fractionation of fennel oil.

Ground fennel seeds were extracted with supercritical carbon dioxide. Small-scale subsequent extractions of the same sample showed that the composition of volatile compounds was changed with the extension of extraction time and only principal volatile components (limonene, fenchone, methylchavicol, and anethole) were present in the last-extracted sample. Fennel oil was successfully fractionated into the essential oil rich and fatty oil rich products in pilot-scale apparatus using two separators in series. Designed experiments were carried out to map the effects of pressure and temperature in the first separator on the yields and compositions of the products. The minimum level of the total undesired components in both essential oil rich and fatty oil rich products appeared at a pressure of 80-84 bar and a temperature of 31-35 degrees C in the first separator. Supercritical CO(2) extraction of fennel seeds resulted in higher yield (10.0%) than steam distillation (3.0%), almost the same yield as hexane extraction (10.6%), and lower yield than alcohol extraction (15.4%). Analysis of the volatile compounds revealed the significant difference of the composition in distilled oil and oleoresins prepared by CO(2) and solvent extractions. Sensory evaluation showed that the CO(2) extraction product and distilled oil were more intense in odor and taste than alcohol and hexane extracts.

Sample preparation by supercritical fluid extraction for quantification. A model based on the diffusion-layer theory for determination of extraction time.

A mathematical model based on the diffusion-layer theory was elaborated in order to calculate the extraction time in dynamic supercritical fluid extraction required to reach a predefined level of extraction recovery. The goodness of the model is demonstrated by application to the extraction of the main neutral cannabinoids from marihuana and hashish samples. For monitoring of the cannabinoid content of extracts normal-phase HPLC was applied. To obtain reliable quantitative results, the extraction time ensuring a predefined level of recovery should be calculated for each individual sample according to the model because the extraction recovery depends on the sample matrix. The systematic error caused by the unextracted compounds can be eliminated by correction of the experimental data. For semi-quantitative determinations, where a knowledge of the correct value of the extraction recovery is not important, as a rule of thumb the extraction of marihuana with carbon dioxide of density 0.9 g/ml at 40 degrees C for 34 min and of hashish for 18 min can be suggested. The application of the proposed extraction times ensured at least a 95% recovery for the main neutral cannabinoids.

Study of the extraction of LSD from illicit blotters for HPLC determination.

The effect of different parameters (extraction method, temperature, time, solvent) on the extraction efficiency of LSD from impregnated papers has been investigated. Designed experiments have been applied according to the Plackett-Burman method. For the quantitative determination of LSD reversed phase ion-pair chromatography has been used with UV detection. The experimental conditions assuring maximal LSD recovery have been determined, as well as the constant and proportional bias of the extraction procedure elaborated.