According to the United Nations, in 2022, global cocaine production hit a record high, with 2,757 tons produced – a 20% increase from 2021. A key issue for enforcement authorities is to efficiently detect the presence of drugs, especially cocaine, using non-intrusive inspection tools.
Such tools can be categorized under two main headings: bulk detection techniques, and chemical sensing techniques. In bulk detection techniques, suspect items to be examined are subjected to electromagnetic or ionizing radiation, and the presence of drugs is determined by the interaction of the bulk content of the item with the probing field. Chemical sensing techniques are based on the chemical analysis of air or wipe samples obtained from within a suspect item, from its exterior surface or from its vicinity, to determine the presence of drugs and/or drug-related constituents. These constituents may be present in the form of vapours or microscopic particles.
When applied to cargo containers, chemical analysis of vapours has proven to be especially effective. All substances are subject to an evaporation process when a specific pressure is applied to them. The vapour analysis process relies on two separate steps. First, an air sample is taken from the container by introducing a teflon nozzle between the container door gasket. The sampling device then extracts the air from the container into a sample trap, where a percentage of vapours coming from the air is collected on a sample card. When a predefined air volume is reached, the system automatically stops. This process last around three minutes per container. The sample card is then transferred to an analyser, which compares the molecules present against a library. The analysis is performed automatically in around two minutes, providing information about the levels of concentration of the targeted particles inside the container and delivering a result (ALARM / NO ALARM) according to predefined thresholds.
Recent developments have made this technology particularly well adapted to maritime containers. Transport by sea usually takes weeks or even months, and the typical amounts of drugs are relatively large, two conditions which favour the generation of vapours. Even when cocaine base and cocaine hydrochloride (whose vapour pressure is lower) is packaged carefully using chemical adsorbents or concealed with a cargo of fruits or inside welded and sealed compartments, surfaces usually get contaminated during manipulation, and this small amount of cocaine generates a concentration of vapours which a well-designed device would be able to detect. Additionally, with time, vapours generated by the concealed cocaine itself find their way out of the cocaine package and out of the compartment containing the package.
Tests done on maritime containers in collaboration with some European Customs administrations using a high sensitivity vapour detection device have provided very high detection rates in containers, including those where the cocaine was concealed using sophisticated methods. The device detected concentrations in the range of parts per quadrillion inside the containers, a quantity which is one million times lower than what is needed by a drug detection dog.
Besides high sensitivity, a device must have the capacity to differentiate the vapours of cocaine from the other vapours (selectivity) emitted by other products in the container, since at the level of ppq concentrations, the number of different compounds in the gas phase in a container can reach the billions or trillions. Tests on containers which do not contain cocaine show that a device with high selectivity has a low false alarm rate of below 5%.
The same technology can be used to detect tobacco, and development is ongoing to enable the identification of the presence of other drugs, especially synthetic narcotics.
More information
daoiz.zamora@miontechnologies.com
