Chemical profiling of cocaine: a powerful tool for drug enforcement

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  • Published: Jan 12, 2017
  • Author: Ryan De Vooght-Johnson
  • Channels: HPLC
thumbnail image: Chemical profiling of cocaine: a powerful tool for drug enforcement

From opium to cocaine

Chemical profiling of cocaine has been performed for the first time in China, successfully separating over 180 different samples into seven main groups of possible similar origin

Globalisation has led to an expansion of drug trafficking. In 2013 alone, an estimated 246 million people—1 in 20 between the ages of 15 and 64—used an illegal drug, 3 million more than in 2012. Cocaine is one of the most frequently used illegal drugs, second only to cannabis, and used by up to 21 million people every year.

In a new study from China, researchers from the National Narcotics Laboratory analysed samples of cocaine in an attempt to crack down on its use in the country. China has a history of drug trade, beginning with opium and increasing in recent years since the country opened its borders to trade and tourism, which allowed illegal drugs to flow too.

Tackling the growing drug problem requires insider knowledge of the groups producing the drugs and their trafficking routes. Traditionally this has been extremely difficult, but a new way to obtain this knowledge is emerging by interrogating the chemical profiles of drugs.

Alkaloid analysis

Cocaine contains a number of impurities, including alkaloids, nitrogen-based compounds such as morphine. Detection of these alkaloids can be used to profile cocaine, with over 70 cocaine-related alkaloids already identified. Some come direct from the coca leaf – the raw material used for the manufacture of cocaine – while others result from a chemical reaction that takes place during analysis.

Several techniques can be used to assay the alkaloids in cocaine, including gas chromatography and liquid phase separation techniques, but these suffer limitations including time-consuming sample preparation and ultimately poor resolution. However, ultra-high performance liquid chromatography (UHPLC) combined with tandem mass spectrometry techniques, such as quadrupole time of flight (QTOF), can detect alkaloids at very low concentrations and offer high resolution.

Having previously used the technique to characterise the impurities in heroin, the team behind this study applied it to cocaine. They successfully identified four common cocaine alkaloids: ecgonine methyl ester, ecgonine, benzoylecgonine and norcocaine, and tentatively identified four others: tropacocaine, 3,4,5-trimethoxycocaine, and cis- and trans-cinnamoylcocaine. They also noted six as-yet unidentified alkaloids, which may have been missed by other studied but could be picked up here thanks to the low detection limits of the technique.

These 14 alkaloids were used to profile over 180 cocaine samples collected in China between 2011 and 2015. The researchers finally performed hierarchical cluster analysis (HCA), a statistical method to arrange data into groups based on their similarities, to classify the samples. “Using HCA analysis, 183 cocaine samples were classified into seven major groups and several links within and between provinces were found,” explains National Narcotics Laboratory scientist Cuimei Liu. In fact, the team found 37 groups of samples associated with different provinces, which could aid police efforts to identify hidden distribution networks.

Forensic intelligence

This is the first time cocaine has been chemically profiled in China and the work reveals a new and efficient method for doing so. Although GC-based methods have been used to reliably detect cocaine alkaloids in the past, the UHPLC-based method applied here showed clear advantages, including low limits of detection, high resolution and selectivity, and greatly reduced analysis time. The time required for analysis was almost half the run-time of GC and GC-MS—making it suitable for routine, high-throughput analysis. “We believe this could be a new simple, rapid and sensitive method for the simultaneous analysis of alkaloid impurities in cocaine,” Ciu says.

The results not only describe a new and efficient method for identifying alkaloids but could also have practical benefits for investigations into illegal drug trafficking. The results could be used to inform police investigations in China, providing intelligence on the possible origin of drugs and the chemical processes used to create them.

Related Links

Drug Test. Analysis., 2016, Early View paper. Liu et al. Applicability of ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry for cocaine profiling.

The Golden Age of Drug Trafficking: How Meth, Cocaine, and Heroin Move Around the World | VICE News (2016).

Wiki: Cocaine.

Article by Ryan De Vooght-Johnson

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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