2.2.2. Sample preparation

One gram of finely ground cannabis soaked for an hour in 10 mL of methanol was vortexed for 2 min after, and then it was sonicated for 30 min. The mixture was re-vortexed for 5, 10, and 15 min, filtered and centrifugated at 13000 rpm for 10 min. The final analysis solution was made by diluting 100 μL of supernatant with 900 μL of the mobile phase of 1:1 acetonitrile: water mixture and injecting it into the LC-MS/MS instrument.

Cocaine was investigated using both GC-MS/MS and LC-MS/MS. The cocaine sample was ground and homogenized into a fine powder. The GC-MS/MS analysis solution was prepared by adding 1 mL of methanol to 1 mg of the powder, vortexed, and then evaporated almost completely with a stream of nitrogen. The residue was reconstituted with 1 mL dichloromethane and centrifugated at 13000 rpm for 10 min. The supernatant was then combined with 950 μL of dichloromethane and injected into the GC–MS/MS instrument. In LC-MS/MS, 50 μL of supernatant were mixed with 950 μL of the mobile phase before injecting into the instrument for analysis.

1 mg of heroin was dissolved in 1 mL methanol, vortexed then centrifugated for 10 min at 13000 rpm. 50 μL of the supernatant was mixed with 950 μL of the mobile phase and then injected into the LC-MS/MS instrument.

Benzodiazepine-containing soft drinks were analyzed using direct injection. To precipitate the coarse particles, the benzodiazepines containing soft drink samples were vortexed for 5 min and centrifugated at 13000 rpm for 10 min 1 mL of the supernatant was drawn and filtered. 20 μL of the filtered sample was injected into the LC-MS/MS instrument. 3 mg of solid benzodiazepines were dissolved in 1 mL of methanol, vortexed, and centrifugated for 10 min at 13000 rpm. 100 μL of the supernatant was mixed with 900 μL of the mobile phase and injected into the LC-MS/MS instrument.

Methamphetamine samples were analyzed using either GC-MS/MS or LC-MS/MS, or both. For GC-MS/MS, 1 mg of pulverized and homogenized powder was mixed with 1 mL of methanol, vortexed, and evaporated almost completely with a stream of nitrogen. The residue was reconstituted in 1 mL dichloromethane and centrifugated at 13000 rpm for 10 min 50 μL of the supernatant mixed with 950 μL of dichloromethane was injected into the GC–MS/MS instrument. For LC-MS/MS, 1 mg of the material was dissolved in 1 mL methanol, vortexed, and centrifugated at 13000 rpm for 10 min 50 μL of supernatant were combined with 950 μL of mobile phase before injection into the instrument.

3 g macerated leaves were drenched in methanol for 15 min, sonicated for 30 min and then vortexed for 2 min. After the solution had been filtered and condensed to near dryness, 2 mL of 0.2 mol/L sulfuric acid was added. 5 mL dichloromethane was used to remove the natural organic components. The aqueous layer was basified with 3 mL of sodium bicarbonate solution. 5 mL of dichloromethane was added to extract cathinone and cathine. The volume was evaporated almost completely dry using a gush of nitrogen gas. Residue reconstitution was achieved using 1 mL of acetonitrile: water (1:1) and centrifugated for 10 min at 13000 rpm. 200 μL of supernatant were mixed with 800 μL of mobile phase for LC-MS/MS analysis.