Narcotic substance indicator devices.
The fight against illegal drug trafficking (sometimes abbreviated as «NV») has recently rapidly transformed from a social and public problem into a problem of ensuring the national security of the Russian Federation.
The reduction in the cost of a dose of heroin to the price of a bottle of vodka has radically changed the situation on the sales market and sharply expanded the area of drug distribution to rural and provincial areas.
An analysis of the development of the situation is characterized by the following circumstances: the sharply increasing pressure of cheap Afghan heroin, the transfer of illegal production of synthetic drugs from distant foreign countries to the Baltic republics, and the intensification of the collection and use of hallucinogenic mushrooms in the North-West region of Russia.
In the analytical chemistry of toxic compounds, the concept of indication includes the procedure for detecting a narcotic substance, identifying the active ingredient, and quantitatively determining the content of the main substance in the sample.
To detect narcotic substances, technical means of control are used based on instrumental physical and physicochemical methods (X-ray diffraction, nuclear quadrupole resonance, chromatograph mass spectrometry, ion mobility spectroscopy) and a method using specially trained dogs.
Fluoroscopy is based on recording changes in the intensity of X-ray radiation after passing through the inspected object and is widely used in industry and medicine.
RAPISCAN X-ray baggage inspection systems of the 300 series with inspection tunnel sizes from 640×320 to 1500×1500 mm can display four color gradations for substances of different densities: orange for low-density substances, green for medium-density substances, such as aluminum, blue for higher-density substances, such as steel, and black for opaque materials.
The systems can be either stationary or mobile (on trailers).
Modern 500 series devices with more efficient radiation generators and computer signal processing allow the operator to distinguish organic compounds with different atomic densities and identify explosives and drugs in baggage items with a sharp reduction in the probability of false alarms.
Nuclear quadrupole resonance is used in analytical chemistry to detect crystalline substances containing atoms with an electric quadrupole moment, such as the nitrogen atom14 (14N).
When objects are irradiated with a sequence of radiofrequency pulses with different repetition periods and frequencies close to the resonant absorption frequencies, the relaxation of excited atomic nuclei causes a detection signal that is received by a radiofrequency coil.
It should be noted that the resonant absorption frequency and relaxation time of the cocaine base (crack) and cocaine hydrochloride nuclei are different, therefore, in the drug detection scanner developed by QUANTUM MAGNETICA (USA), two radio frequency heads are mounted, the coils of which are tuned to the resonant absorption frequency of cocaine chloride and cocaine, respectively.
In principle, this method was developed for the rapid and safe detection of drugs in frozen food packages, such as shrimp blocks, without damaging the items being inspected.
The inspection of one piece of cargo on a conveyor line takes 6 seconds.
Detection sensitivity is highly dependent on the specific characteristics of the substances being detected and the ratio of the dimensions of the cargo and the coil (antenna).
The method also proved to be very effective for detecting explosives and was implemented to create the QSCAN-1000 security system for Los Angeles Airport Terminal 7.
Systems for screening postal items for explosives and narcotics are currently being developed.
The leader in domestic developments in this area is LOGIS at the Research Institute of Instrument Engineering.
Physical methods – X-ray and NQR – are designed to detect concentrated masses of NF and even in the best examples have a detection limit for narcotics at the level of fractions of a kilogram.
The specificity of detecting narcotic substances using the NQR method is quite high, fluoroscopy in widely used models is not specific to narcotic substances and only allows detecting places where contraband is hidden with X-ray absorption indices that differ from the packaging.
Specificity in this context should be understood as a parameter inversely proportional to the frequency of false positives of the method.
Highly specific methods have a very small number of false positives during operation.
The disadvantages of physical methods include shielding of the signal by metal containers (packaging) and, as a consequence, the impossibility of detecting narcotic substances in metal containers.
For non-conductive containers, physical methods are optimal and are actively used even on conveyor lines.
Physicochemical methods for detecting narcotic substances (chromatographic and ion-drift devices, sensor sensors) determine the presence of narcotic substances by the volatile components of the sample.
To achieve high sensitivity in detecting narcotic substances in chromatographic and ion-drift methods, sample concentration is required, so a fairly large volume of air is sucked through a sorption preconcentrator.
The preconcentrator is placed in a thermal desorber and the concentrated sample is introduced into the analytical tract of the device.
Chromatographic methods allow identification of narcotic substances by retention index and, in the case of a mass-spectral detector, by ionic masses of fragmentation products of narcotic substances.
It should be noted that in the process of using a sorption preconcentrator, not only the target component of the narcotic substance is concentrated, but also all other organic impurities contained in the analyzed air.
This circumstance can significantly worsen both the process of chromatographic separation and the process of identifying narcotic substances, since the content of solvent vapors or fuels and lubricants in the air, as a rule, significantly exceeds the content of narcotic vapors.
In this regard, the actually achievable specificity of detection and identification of narcotic substances in methods using a preconcentrator must be assessed experimentally.
A real-life testing of a domestic chromatograph mass spectrometric device at Domodedovo Airport showed insufficient sensitivity for detecting narcotic substances and a high probability of «false positives» when analyzing passenger baggage.
The ion-drift principle is implemented in various versions for detecting narcotic substances and explosives.
The ITEMISER detector (photo 1), developed by Ion Track Instruments, uses Ion Track Mobility Spectrometry technology.
The analysis involves sampling the air with a paper filter with a vacuum capture or by wiping particles from the surface being examined, then heating the filter in the device's desorber.
The heated air is cleaned through a membrane and enters an ionization chamber, where it is ionized by beta rays.
Positively and negatively charged ions enter a cell with a mesh electrode and a collector.
The results of the ion mobility assessment allow for the identification of an explosive at a level of 100–300 pg and a narcotic at a level of 10–30 ng.
Photo 1. ITEMISER instrument complex
The most common type of devices that use the principle of ion mobility spectroscopy (Ion Mobility Spectroscopy) to detect narcotic substances and explosives are the IONSCAN devices (photo 2) from the Canadian company Barringer Instruments, which effectively detect and identify narcotic substances and explosives in trace quantities on any surface.
The main advantage of the IONSCAN system is the ability to identify explosives and substances of various chemical compositions (cocaine, heroin, amphetamines, LSD, PCP, etc.) and TNT, RDX, PETN, nitroglycerin, tetryl, respectively.
Microscopic particles of explosives and narcotics settle on all surfaces that they come into contact with, such as hands, clothing, and suitcases.
The IONSCAN sampling device is a miniature autonomous vacuum cleaner in which the air sample is sucked through a flat filter.
The same filter can be used to simply wipe the surface of a suspicious object. The filter with the sample is placed in a thermal desorber, the evaporated particles are ionized in the gas flow and enter the «drift» cell, where their mobility is measured.
The collected samples are processed automatically, within a few seconds a «pass/hold» signal is issued, if narcotic substances and explosives are detected, the system identifies them and displays the results on the display.
The IONSCAN 400 series allows detection of 30 NV and explosives within 5 seconds with a sensitivity threshold of 5 ng for narcotics and 0.2 ng for explosives.
The device consists of two modules with a total weight of 37 kg.
Photo 2. IONSCAN installation
Sensors are certainly promising for the indication of narcotic substances, but the most developed models at present are not specific and depend to a large extent on the variable components of the air environment, such as humidity, temperature, dustiness.
Improving the technology for obtaining highly specific coatings for microsensors, up to the creation of coatings based on biotechnology using antibodies, can radically change the situation in the market of devices for technical control of cargo.
Thus, instrumental methods of technical control are based on different principles, have different sensitivity, speed of action, some of them impose special requirements on the dimensions of the inspected baggage.
Therefore, the optimal choice of method should be made taking into account the specific conditions and requirements in each individual case, giving preference to universal methods that allow detection of both narcotic substances and explosives.
The main disadvantage of instrumental methods is their stationarity and the relatively high qualification of the operator.
The use of specially trained dogs to detect narcotics and explosives is actively practiced throughout the world along with expensive instrumental methods.
Unlike physical methods of detecting narcotics, which work on solid crystalline narcotics in the range from trace amounts (in the case of ion-drift methods) to fractions of a kilogram (in the NQR method), dogs detect drugs by the volatile components of narcotics.
Volatile components of drugs penetrate semi-permeable membranes of packaging, such as commonly used polyethylene film, much more effectively than dust particles, so in most cases dogs demonstrate higher sensitivity in detecting drugs than devices.
The sensitivity of various biological objects to odorous substances varies greatly.
Thus, a person senses the presence of acetic acid (one of the volatile components of heroin) if one cubic centimeter of air contains 5×1013 molecules, while a dog only needs 5×105 molecules in the same volume of air.
It should be noted that the sensitivity of the most modern physical and chemical instrumentation is at the level of 109, therefore, in the foreseeable future, the canine service will be the basis for field detection of narcotic substances during inspection of vehicles and passenger baggage.
Canine detection methods are characterized by maximum detection sensitivity, mobility, the possibility of use in field conditions, prevalence in federal and private structures, and relatively low costs for maintaining the service.
The disadvantages of using biological objects to detect narcotic substances include the need to assess the dog's performance in the object's area using a control bookmark and the interfering influence of distracting factors.
With the advent of canine imitators of narcotic substances (heroin, cocaine, amphetamines), which are white powder composite materials consisting of an odor-inert matrix with the addition of volatile organic markers, structurally similar to the telltale signs of real drugs, the situation with the preparation and training of special dogs has changed radically and has ceased to be criminally tinged, as in the case of using real narcotic substances for training.
Due to the non-absolute specificity of the methods for detecting narcotic substances, all cases of positive or questionable results require a procedure for identifying narcotic substances.
The identification procedure can be performed both in stationary conditions of forensic laboratories using TLC, GLC, HPLC, Chromatomass and IR spectrometry instrumental methods, and in field conditions using express methods based on wet chemistry.
It should be noted that the highest reliability of identification of narcotic substances is provided by methods of chromatographic analysis with a witness, which is a standard sample of the narcotic substance or its solutions.
Accordingly, the laboratory must provide for the possibility of storing both the narcotic substances themselves and their solutions.
It should be taken into account that both the narcotic substances themselves and their solutions are prone to decay, therefore both the storage procedure and the possibility of creating standard samples of narcotic substance solutions (currently mainly of imported origin) are far from the realities of today's domestic analytics.
Nevertheless, experts from forensic laboratories of the Internal Affairs Directorate, who carry out the bulk of drug examinations, cope with their tasks of identifying the most common drugs.
When identifying drugs for screening a large number of samples, express tests in various versions of equipment are widely used.
The development of the first generation of rapid tests was a set of disposable tests of ampoule equipment.
The analysis procedure was reduced to placing a sample of powder of a suspicious sample in a plastic bag and sequentially breaking the ampoules with reagents located in the same bag. The color of the solution was compared with the color mark on the bag.
The advantages of this type of equipment are a wide range of tests for almost all types of drugs, the disadvantages are the need for a large sample volume, difficulties in opening ampoules in a package and a limited number of tests in the test kit.
Among foreign options, the most common are NIK kits (photo 3), USA. Domestic ampoule tests are produced at AOZT «LSI» (SIGMA-M) and at chemical plants in Tula and the Urals.
Photo 3. NIK reagent kit
Second generation tests have become reusable and the most widely used tests are those in aerosol equipment (heroin, cocaine and cannabis sprays) and drop equipment.
In the case of aerosol equipment, the analysis procedure is reduced to placing a powder sample on a paper backing with an adhesive layer and then spraying with an aerosol spray.
A paper backing with an adhesive layer is necessary to prevent the powder from being physically carried away by the aerosol flow. Two aerosol formulations are used to detect cannabis, one for cocaine, one for heroin, and special indicator paper.
The advantages of aerosol tests are ease of use, long shelf life, compact placement, and the disadvantages are the limited range of drugs that can be determined (it is impossible to perform an aerotest with caustic liquids), so opiates, amphetamines, and LSD have to be determined using additional methods.
Almost all aerosol tests for drug detection are imported (Germany, Israel, Switzerland), the first attempt to produce domestic aerotests in AOZT «LSI» in 1994 was unsuccessful due to poor compatibility of indicator formulations and construction materials of domestic aerosol cans. These shortcomings were subsequently eliminated.
With drop equipment, indicator solutions are placed in dropper bottles with a volume of 5 — 10 ml.
The analysis procedure consists of placing a powder sample on paper and applying a drop of indicator formula to the sample from a dropper bottle. The color of the reaction zone is compared with the color of the mark on the bottle.
This method does not require adhesive backings.
In addition, several grains of powder are sufficient for the analysis, which makes it possible to systematically analyze small amounts of sample, including squeezed out of pockets. One bottle is sufficient for 100–200 analyses.
Abroad, the drop test kit is produced by BDH (Great Britain) and SIGMA (USA), the domestic analogue of the «DELTA» kit, produced by the «Laboratory of Indication Means», consists of seven dropper bottles, allowing for group determination of cocaine, barbiturates, cannabis, LSD, amphetamines and opium alkaloids, including heroin. The dimensions of the kit are the same as the size of a camera bag.
The sensitivity of express tests is at the level of micrograms of the narcotic substance, but the specificity of determining the narcotic substance is insufficient, since a number of drugs under the conditions of analysis give similar color characteristics of the reaction zone.
Nevertheless, express tests are invaluable for the prompt verification of suspicious samples in the field, since they work without water and electricity.
Thus, various instrumental methods and a canine service can be used to detect narcotic substances, and the optimal option is a combination of several methods.
The efficiency of detecting narcotic substances can be increased by an order of magnitude by organizational measures alone, for example, if the canine service of customs authorities is separated into an independent unit and provided with vehicles to organize mobile independent checks at posts and on roads, and all schedules and approvals for these checks are abolished.
The work of the «Black Customs» in Germany is organized in a similar way.
The absence of numerous approvals and regular checks will lead to a reduction in information leaks, the presence of own vehicles will lead to mobility and surprise checks and, accordingly, to an increase in the effectiveness of the measures.
In terms of increasing the efficiency of physical and chemical methods, it is advisable to refocus developers on the indication of volatile compounds-markers of narcotic substances, which have a greater penetrating ability than aerosol particles of narcotic substances, and this circumstance is capable of increasing the sensitivity of detecting narcotic substances by an order of magnitude.
The widespread introduction of express tests into the practice of not only customs, but also the Federal Border Service, the Internal Affairs Directorate and the Federal Security Service would significantly contribute to the prompt resolution of many issues at the local level.
Well, and probably a single drug control agency for all special services, like the American model, would not have made the situation any worse.
Conclusion
1. The identification of narcotic substances is currently handled exclusively by the forensic departments of the Main Directorate of Internal Affairs, that is, specialists working exclusively according to their own departmental methods, therefore I do not consider it possible to give them any recommendations on detecting narcotic substances.
2. Despite the well-known opposition to canine detection methods on the part of adepts of special equipment, one should be aware that in our country, instrumentation for detecting narcotic substances and explosives is a task for the distant future, while this process must be implemented now and on an increasingly large scale. In addition, one should take into account a certain psychological aspect of using dogs, as often the mere appearance of dogs in the customs hall leads to the dumping of contraband drugs.