A basic need of any law enforcement agency is to be able to positively identify controlled substances in seized drug samples, as well the purity of the drug, which will support legal proceedings and, hopefully, result in successful convictions. Research aimed at shedding light on the chemical profile of seized drugs is also of great relevance in determining their characteristics, such as their place of origin and processing, as well as trafficking methods. Combined with the results of criminal investigations, this data could be used to establish connections between drug gangs and suppliers, and to trace drug distribution networks. This article presents an initiative undertaken by the Italian Customs Laboratory to go beyond the usual tests for identification and quantification purposes, and to undertake cocaine profiling using a rapid method based on infrared spectroscopy, and more specifically, Fourier Transform Infrared (FT-IR) spectroscopy.

Cocaine is the most widely used narcotic drug, making the determination of the geographic origin of illicit cocaine the focus of intense investigation by the forensic community. The Drug Enforcement Administration (DEA) in the United States (US) has created a cocaine signature programme which provides for in-depth signature analyses to be performed on samples obtained from bulk seizures throughout the US and from around the world. The applied analytical methodologies enable evidence to be given on how and where the coca leaves were processed into a cocaine base (determining the geographical origin), and how and where the cocaine base was converted into cocaine hydrochloride salt (determining the processing origin).

In Europe, a cocaine signature programme such as the one created by the DEA does not exist, and therefore determining the origin of seized cocaine is highly hypothetical. In most cases, only the country of provenance is known. Even though drug profiling is not yet officially done by the Italian Customs Agency, its Directorate for Chemical Laboratories decided to perform a study using about 30 cocaine samples coming from large Customs seizures, corresponding to a total weight of about 1,000 kg.

The aim of this study was to verify whether a “fast profiling” method, based on infrared spectroscopy, could be used as a useful tool to enhance and speed up controls carried out by the Customs authority, and to move these controls to the field where the seizures actually take place thanks to the fact that FT-IR spectroscopy equipment is a mobile identification system.

Most mobile laboratory teams are furnished with scientific equipment, characterized by smaller overall dimensions than those of fixed laboratories, but with excellent accuracy in relation to analytical responses. Among other equipment, most mobile team will use FT-IR spectroscopy – the method of infrared spectroscopy that is now more commonly used – to determine the chemical composition of samples.

As the infrared spectrum of a molecule is literally its “fingerprint,” the pattern of peaks in the infrared spectrum of a substance is unique to that substance. If two molecules have different chemical structures they will have different infrared spectra.

FT-IR spectroscopy has been applied as a fast method in characterizing commodities and in discriminating between several commodities, such as defective and non-defective coffee beans prior to roasting for example. However, it is underutilized in many forensic laboratories in the field of drug profiling.

Other devices, such as mass spectrometry coupled with gas-chromatography, are usually used for drug profiling. They have a higher discrimination power, i.e. they can identify most of the substances present in a mixture, while FT-IR recognizes fingerprints of pure substances. However, these techniques are time consuming.

For purposes of the study, the Italian Customs Laboratory first did time consuming analyses in order to detect minor alkaloids and residual solvents in the drug samples. Then the laboratory used Attenuated Total Reflectance FT-IR (ATR/FT-IR) to analyse the drug. Finally, the results of the two methods were compared.

First, the cocaine samples were analysed. More specifically, information on the chemical signature of samples (analysis of minor alkaloids and residual solvents) was collected. The results were then analysed against both knowledge coming from scientific literature and information about the provenance countries of the seizures. This allowed the laboratory to make a hypothesis about the geographical origin of samples: 92% of the cocaine might be of Colombian origin; 6% of Bolivian origin; and the remaining 2% shows elements of similarity, although not totally identical, with the samples of Bolivian origin.

The results of these analyses were used as a starting point for the development of a “fast profiling” method, based on ATR/FT-IR spectroscopy and statistical tools. First, only pure samples were analysed as this technique is best performed on pure substances. Second, the variation in the fingerprint of pure cocaine samples “cut” with adulterants or diluents was evaluated.

Eventually, the FT-IR method for comparative analyses of cocaine seizures proved to be very fast and effective. Even if the new method was developed by analysing samples that were free of adulterants or diluents, it still works when the sample contains 50% of cocaine and only one added substance, and 60% of cocaine with more than one added substance.

The method can be usefully employed for the comparative analysis of large seizures too, because, although they sometimes contain added adulterants such as levamisole (a synthetic compound used as an anthelmintic drug – especially in animals, and in cancer chemotherapy), the concentration of cocaine is often still high enough for the method to work.

Drug profiling is not yet one of the Italian Customs Laboratory’s official duties. Drugs are only analysed for identification and quantification purposes at the moment. However, this study showed that it is possible to use ATR/FT-IR spectroscopy as a fast profiling method. Some of its advantages include shorter analysis times (the entire sample analysis is typically completed in less than a minute), reduced sample preparation, and rapid assessment of possible heterogeneities in a big seizure due to the different origins of the respective seizure samples.

Work also remains to be done on the harmonization of the methodological approaches on drug profiling among countries, including on the use of FT-IR spectroscopy. The complete characterization of a drug sample coming from the illegal market, done for comparative purposes, may need various analytical steps, and the methodological approaches used differ greatly sometimes. As a matter of fact these procedures are often difficult to standardize.

However, one should not forget that the stakes are high. Ensuring a uniform approach by different laboratories will enable them to compare their results, and open possibilities, from an intelligence perspective, on who was involved, how the drugs were made, where they came from, and what routes they travelled.

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maria.monfreda@agenziadogane.it