WHAT's THE POINT? Profiling heroin samples consists of collecting data concerning key impurities in heroin and associating this data to the original batch the heroin was sampled from. This allows for different heroin profiles to be compared. The use of profiling is similar to the concept behind collecting fingerprints and DNA samples. The idea is to create a large database with impurity data from as many heroin samples as possible. This allows for newly found samples to be compared to previously acquired samples, based on the dosage of impurities within it. If two powders possess the same proportions of characteristic impurities within them, one can assume they were created following the same fabrication process, and therefore possess the same origin, traffic routes and dealers. This allows a wealth of information to be acquired. If a given type of heroin continues to appear on the street long after an arrest, it can be assumed this traffic source has not been entirely or effectively dismantled. In addition, information from the fabrication process can be used to hypothesize where fabrication might have taken place and also what precursors(commercial chemicals used in the creation of illicit drugs) were used, which is helpful for precursor-monitoring programs. Information as to the health risks associated with a given drug can also be extracted from heroin profiling allowing authorities and awareness initiatives to work more effectively for health and safety purposes. The United Nations Office on Drugs and Crime(UNODC) Identifies two main purposes for drug profiling: tactical ones and strategic ones. Tactical ones serve to gather intelligence as to the range and size of a trafficking network while strategic ones serve as information on how drugs are made and handled. The UNODC claims “ For drugs derived from plant sources it is most often possible to assign geographical origin, if at all, in only the most tentative sense when the analytical technique employed exclusively targets the major alkaloids. However, there are notable exceptions, perhaps the most notable being those heroin samples originating in South-East Asia. The relative ratios of the alkaloids present in the majority of South-East Asian heroin samples are distinctly different from those found in heroin samples originating in other source regions. As a result, many South-East Asian heroin samples can, with reasonable certainty, be distinguished from those samples originating elsewhere simply by comparison of major alkaloid analyses.” This shows the usefulness of using data from the chemical composition of heroin seizures to determine the geographical location of where heroin is manufactured. SO HOW IS IT DONE? To acquire data on heroin samples that are brought in by the police, heroin laboratories can use different methods. Forensic laboratories in France are currently beginning to share their methods in order to standardize them and therefore be able to share databases. Many different methods are described in the UNODC's "Methods for impurity profiling for heroin and cocaine". To study the proportions of impurities found in heroin, they need to be separated. Profiling usually focuses on organic impurities, and therefore a method for detecting organic molecules is necessary. Most often, this is done by dissolving the heroin samples into an organic solvent(for example, chloroform). These samples are then used for Gas Chromatography with a Flame Ionization Detector(GC-FID). The way this machine works was described in a previous blog post. To state the mechanism simply, the machine separates the impurities of interest and the solvent and then passes them through detector. A computer records all data from the detector, and tags the peaks on the resulting chromatograms with molecules they characterize. The computer automatically calculates the area underneath of each of the peaks, the area of these peaks being proportional to the quantity of the chemical present in the sample. In the Toulouse Forensic Laboratory, five typical impurities are paid attention to: acetylthebaol(ACTH), acetylcodein(AC), 06-acetylmorphine(06-MAM), papaverine(PAP) and noscapine(NOS). In the Toulouse Forensic laboratory, the areas of each of the five peaks that represent the aforementioned molecules are entered into a database named OTARIES, as well as the area of the peak representing diacetylmorphine(the name of the heroin molecule). This software can then used to compare the data from the heroin sample to all others that have been entered in the database. For the comparison to be made, two samples are chosen, and each of the areas from the impurity peaks are normalized(divided) by the area of the peak for diacetylmorphine and then the five impurity values are entered into a mathematical formula wich calculates what is called called the square cosine similarity(then multiplied by 100). This formula returns a value between 0 and 100 based on how similar the proportions of impurities are. If the value is 100, the two samples are identical, and if the value trends towards 0, then the samples are extremely different, and are therefore unlikely to have originated from the same batch. The software OTARIES will list all samples in the database that result in similarity values that exceed the value 99.85. If the value exceeds 99.92, then forensic analysts will consider that samples are from the same batch and geographical origin. If the value is between 99.85 and 99.92, then the test was inconclusive and otherwise, the samples are not considered to be linked. All samples must be run twice to confirm the results of the test by replicate.
For interpreting results, there is no standardized method, and the use of cosine similarity is only typical of laboratories in Lyon and Toulouse in France. This has made data sharing difficult and therefore databases are not always very complete, therefore hindering the usefulness of the process. However, as more samples ares seized by authorities, the database will grow and profiling become a more reliable method of intelligence gathering. After this, the forensic analyst sends his report and conclusions to the judge that has ordered the profiling to be made. Sources: 1. Toulouse Forensic Laboratory Staff and Protocols 2.“A quick and automated method for profiling heroin samples for tactical intelligence purposes”. Dufey V., Dujourdy L., Besacier F., Chaudron H., LPS LYON, 2006. 3. UNODC, "Methods for Impurity Profiling of Heroin and Cocaine", 2005 4. Map Image: United Nations Office on Drugs and Crime, Drug Trafficking, https://www.unodc.org/unodc/en/drug-trafficking/, consulted July 2017
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