Área de trabajo: Forense
Título: “Sales de Baño” y Canabinoides Analizados por GC-IR.
Título original: Bath Salts and Cannabinoids Analyzed by GC-IR.
Autor: Glenn Everett, William Stanton, Tennessee Bureau of Investigation, Nashville, TN, USA Michael Bradley, Ph.D., Thermo Fisher Scientific, Madison, WI, USA
Drug case criminal prosecution relies upon laws specifying what is and what is not legal. Underground chemists try to avoid prosecution by modifying illegal materials to produce synthetic “designer drugs” which may slip through legal loopholes. Recent designer drug targets include cathinones and cannabinoids. Cathinones and related drugs are found on the street labeled as “Bath Salts” (due to a resemblance to commercial bath salts, though completely unrelated; methcathinone is a common example).
Synthetic cannabinoids have an affinity for the cannabinoid receptor in the brain, providing a “high” similar to marijuana. Marijuana itself contains over 50 different cannabinoids. The Tennessee Bureau of Investigation (TBI) laboratory has considerable experience analyzing street samples of both cathinones and cannabinoids. Crystalline cathinones tend to be sold in single-dose capsules, labeled either as bath salts or plant food (though never used in either capacity) and bearing a disclaimer of “not intended for human consumption.” The capsules often contain relatively pure cathinones in amounts above an effective dosage, leading to toxicity effects ranging from headaches and nausea to death.
Typical samples of cathinones arrive at the TBI laboratory as capsules or loose powder. The drug is converted to a base by mixing with 0.5 M NaOH to improve the chromatography. The solution is then separated with chloroform for injection. Cannabinoids arrive in bags containing plant matter and visibly resembling potpourri (flaked leaves).
A portion of the sample is soaked in methanol. Minimal methanol is added, just wetting the plant material and leaving a small amount – a drop, ideally – of extra liquid. If an excessive amount of methanol is present, the sample may need to be dried down to concentrate the drug. A GC syringe is used to uptake 2 microliters of the liquid; no other preparation is needed. Standards of the cannabinoids and bath salts (Cayman Chemical®) were mixed with methanol to obtain 1 mg/mL solutions. These were injected in the same manner as the evidence samples.
The resulting reference spectra were stored in the TBI Gas Phase Library, which can be obtained at no charge by qualified Forensics Laboratories through Thermo Fisher Scientific™. The Thermo Scientific Nicolet™ iS™50 FT-IR spectrometer equipped with the iS50 GC-IR module is ideally suited for this analysis. Figure 2 shows the system using a Thermo Scientific TRACE™ 1310 Gas Chromatograph coupled via a heated transfer line to the spectrometer. The GC module contains a liquid nitrogen cooled MCT-A detector for high sensitivity. For this work, the Thermo Scientific OMNIC™ Series software collected more than one spectrum per second consisting of 4 scans at 8 cm-1 resolution (0.7 second acquisition time). As seen below, this yielded excellent signal-to-noise. Further signal-to-noise improvement resulted from co-addition of spectra around the peak maximum.
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