Drug screening methods pdf

While quantification of unknown substances is technically possible, it really comes down to a case-by-case basis and is generally a laborious process undertaken by advanced to expert level technicians and chemists in forensic laboratories.

It is highly unlikely that quantification would be viable using this technology in this kind of setting. Recent advances in IR technology have allowed for the development of portable IR devices.

When reference spectra are available, most compounds can be unambiguously identified based on their IR spectra. IR cannot distinguish enantiomers similar to MS [ 24 ]. Free base is usually more volatile and normally has a lower boiling point, allowing the substance to be smoked.

The salt form is usually more stable and tends to be crystalline and dissolvable in water, allowing for ingestion, insufflation inhaling through the nose , or injection.

A common example is crack cocaine free base and cocaine salt ; they are in fact the same drug cocaine , and the actual effect on the body is the same, but due to different absorption and dosages based on method of use, it is possible to observe a spectrum of differing responses to each of the drugs. One of the notable benefits of IR spectroscopy is that it does not destroy the sample provided—an important consideration when working with drugs and the people who use them.

As well, it requires only a very small sample size in the range of milligrams or less. Additionally, samples can be studied in virtually any physical state primarily solid or liquid. Interference is very common and causes difficulty in identification. The level of expertise required to use this technology varies depending on the device. There are portable IR devices on the market that have been optimized for basic to intermediate knowledge base, such as by outreach workers. These devices can analyze the obtained spectrum and search internal databases to display the identified substance or substances in a mixture to a certain concentration, based on the specifications of a given device.

This is considered presumptive or qualitative testing, in that it may only give an accurate breakdown of the constituents of a substance or mixture and sometimes offer a semi-quantitative analysis i. For quantification as percent mass by total mixture weight , Sorak et al. Many other IR devices also require at least an intermediate level understanding of the procedures and some require advanced to expert knowledge to correctly analyze and quantify the substances including operation of the equipment and database searching.

Raman spectroscopy is an optical technique based on the inelastic scattering of radiation after it interacts with matter. The interaction of incident radiation with the molecules of the substance gives spectral vibrational information [ 26 ].

The technique involves shining a laser on a sample and detecting the scattered light. A small amount of the scattered light is shifted in energy from the laser frequency due to electromagnetic and molecular interactions in the sample [ 26 ].

Plotting the intensity of the shifted light versus frequency gives a Raman spectrum of the sample. An exciting breakthrough in this technology is the development of handheld, portable Raman spectrometers.

These devices also search databases in real time at a device level and give a clear readout of what substance s were detected. Virtually, any drug can be identified with Raman spectroscopy.

It can be used to determine active pharmaceutical ingredients APIs as well as molecules with the same chemical formula but different molecular arrangement and polymorphs. This is important as many of the novel psychoactive substances that have been emerging are isomers, derivatives, and analogues of many of the classical drugs of abuse.

Being able to differentiate between small differences in physical or chemical structure aids greatly in unambiguous identification. Portable Raman spectroscopy has even been reported to be able to detect the date-rape drug rohypnol flunitrazepam in spiked beverages [ 27 ].

Raman spectroscopy may have difficulty in identifying substances that exhibit strong fluorescence. These substances tend to be plant-based narcotics such as heroin. However, with proper sample preparation, it is possible to analyze even these substances.

The TruNarc Raman spectroscopy device has been shown to have a very high level of agreement with laboratory results MS for cocaine, heroin, and methamphetamine; inconclusive results are generally related to illicit substances that are present at extremely low percentages of the total mixture. Others have detected amphetamine residues milli- to micrograms on paper currency using Raman spectroscopy [ 29 ].

The Raman technique as a whole is able to identify and quantify depending on the device a wide range of illicit drugs, even in the presence of contaminants and adulterants [ 26 ]. RS is rapid and non-destructive, does not require chemical reagents, can detect separate substances in mixtures, is not subject to interference from water or moisture, and importantly, can detect substances through transparent packaging such as plastic bags and glass containers.

Little or no sample preparation is required, although some sample preparation is required for substances that exhibit high fluorescence including some cutting agents. RS is ideal for both organic and inorganic species and can be used for both qualitative and quantitative analysis.

Due to the similarity to IR detecting forms of molecular movement to identify , Raman has similar issues with quantitative analysis. While quantitative analysis can absolutely be done with Raman spectroscopy, it can be a much more difficult process that may not be possible in a harm reduction setting. Due to the difficulty of quickly and easily performing quantitative analysis on many unknown samples, an important consideration for outreach is that portable handheld devices specifically designed to detect drugs of abuse are available.

Qualitative results can be obtained in a fraction of seconds to several minutes. Like all of the previous devices, care must absolutely be taken in selecting the appropriate tool.

Advanced knowledge is required for devices that are not optimized for drug testing. The level of expertise required to use this technology varies depending on the device, similar to IR. Sorak et al. Other bench top or lab specific devices are most often not as simple and may require some database searching and interpretation of results. This can push the level of expertise required to intermediate, advanced, or expert, depending on the chosen device. In X-ray diffractometry X-ray D , the drug sample is bombarded with high-energy X-ray radiation and crystalline atoms in the substance cause incident X-ray beams to diffract in various directions [ 30 ].

This allows for the determination of the spatial structure of molecules by measurement of how X-ray radiation is scattered by the molecular crystal lattice structure. By measuring the angles and intensities of the diffracted X-rays, it is possible to produce a three-dimensional picture of the density of electrons in the crystal, and, from this, it is possible to determine the positions of the atoms in the crystal as well as their chemical bonds and other structural information [ 30 ].

Any crystalline or partially crystalline substance i. This method is generally restricted to solid substances. X-ray D is used to identify precise chemical forms but not to quantify them.

It can be used to identify diluents or adulterants [ 31 ]. This method is sensitive to both polymorphs and contaminants common in illicit drugs. X-ray diffractometry determines structural information of the substance, so the substance can be identified with a very high degree of accuracy.

One benefit of X-ray D is that it requires no sample preparation and does not destroy the substance being tested. As well, only a very small sample size is needed milligrams to micrograms [ 31 ].

While it is the most reliable structural determination method and can determine the structure of currently unknown molecules, it is not suitable outside of a laboratory environment.

Thus, this method requires a high level of training and safety procedures and is restricted to laboratory environments. The skill level involved in operation is advanced to expert.

These chemical tests result in the formation of unique microcrystals of a given analyte when a specific reagent is applied. Microcrystals are compared based on shape, size, color, and spatial arrangement [ 34 ]. Several commonly abused substances can be identified, including cocaine, heroin, methadone, GHB gamma hydroxybutyrate , ketamine, phencyclidine, amphetamines, and methamphetamine [ 34 ].

This is provided that other substances do not react in a similar way, if at all, with the reagent, and provided that impurities, dilutents, and adulterants do not prevent or mask the formation of characteristic microcrystals for the drug tested. In these cases, a microcrystalline test can be considered highly characteristic but non-specific enough for a confirmatory test. Sensitivity is high as samples require only micrograms of substance.

The benefit of microcrystalline tests is their relatively low cost. Minute amounts of reagents are required. Instrumentation is simple; however, this method does not quantify how much of a substance is present.

Unfortunately, the sample that is tested is destroyed in the process, which may be less than ideal for people who are bringing the samples for identification.

The expertise required is intermediate to advanced and requires adept interpretation of results. Thin-layer chromatography TLC is a technique in which a sample is placed onto a planar stationary phase then a liquid mobile phase resulting in capillary action.

The analyte is either adsorbed to the stationary phase or is in the mobile phase, and the time spent on the stationary phase or time spent in the mobile phase determines its retention time. The result is a plate of spots separated components of the mixture that have moved various distances on the stationary phase. Using TLC, it may be difficult to separate and identify novel psychoactive substances [ 36 ].

TLC performs fairly poorly at separating complex mixtures. Sensitivity is in the micro-nanogram range. Specificity can range from intermediate to high depending on the mixture, and measured retention factors can be used to make a preliminary identification of a substance but are not specific to a single compound [ 35 ].

In order to increase specificity in cases of similar retention factors, it must be used in conjunction with another technique such as Raman spectroscopy or colorimetric testing or in the case of UV active species, UV. TLC is a relatively low-cost way to test substances and demonstrates good sensitivity and speed of separation.

It can be used as a presumptive test with a fairly high degree of accuracy depending on sample purity. While TLC can identify some known substances in provided samples, it does not indicate quantify how much of a substance is present in the sample. TLC is relatively simple to use and interpret and is thus suitable for basic to advanced skill level.

This means that someone with basic skill may be able to perform a test following instructions but have trouble interpreting the results, whereas someone with intermediate to advanced skill level would have greater ability to interpret a test and could supervise basic skill level users. The indicator chemically reacts with the analyte and causes a reaction that creates a certain color staining depending on the analyte tested.

Spots are then compared visually with reference charts, the current standard being the Munsell color charts. There is a method that bypasses the human eye and its subjectivity by using a simple smartphone app to identify colors with high precision and accompanying software that matches the results in a searchable database [ 38 ].

This allows for a more precise quantitation of the color and therefore higher accuracy identification. Colorimetric tests exist for most drugs of abuse, including cocaine, various pharmaceutical opioids, amphetamines, LSD lysergic acid diethylamide , cathinones bath salts , heroin, and fentanyl.

There may be other novel psychoactive substances that do not yet have any associated colorimetric tests. Each specific named test will have information on what analytes it can be used with. Unfortunately, the test also destroys the sample provided.

That said, color tests do not require much sample: if it can be seen, it can be tested. Colorimetric tests can be quite sensitive, with limits of detection in the microgram range depending on the spot test utilized and the analyte [ 37 ].

Multiple tests with multiple reagents can be used if a mixture of drugs is suspected, though each test requires in the low milligram range of substance and destroys the substance in testing. With the proper standards, these tests can be quite specific, although multiple analyses may be required for high specificity. Some knowledge about what the substance is supposed to be and about general appearance of certain substances can increase specificity.

Colorimetric tests are considered presumptive, in that they can only identify presence or non-presence of a particular substance based on the test administered. A typical test is not sufficient for a suspected mixture or even an unsuspected mixture if there is any reason at all to have suspicion of the substance. An example battery test protocol for considerations of how to test a suspected mixture is included below.

Actual color results may vary depending on the concentration, whether the drug is in salt or free base form, additional diluents, or contaminants; positive result may indicate a specific drug or class of drugs present, but not always specific for a single drug or class.

Colorimetric tests rely on simple chemical reactions and produce visible results that can be interpreted with the naked eye. Reagents and laboratory materials needed are inexpensive and readily available and can be performed with minimal training. Because each individual perceives color uniquely and because lighting conditions are not always optimal in non-lab settings, accuracy can be greatly enhanced with the use of smartphone apps to report color test results quantitatively [ 38 ].

Overall skill level required is basic to intermediate. A basic user can run the simple test and obtain results, whereas an intermediate user would run a standard protocol. An example of an intermediate protocol would be to run a battery of tests based on how much sample can be obtained without objection from the user.

The tests should be based on an educated guess system, narrowing down possibilities through analysis and questions. Potential questions would be as follows: What did the user think it was or was told it was? What are recent novel substances that have been appearing in the clinic or on the street lately? What is the most dangerous substances worth testing for smallest window of dosage? Is there any knowledge of common mixtures, such as opioid mixtures? The tests should be interpreted within a maximal min window.

The tests can be analyzed via smartphone or at least under good lighting if using the naked eye in order to most accurately determine color. The tests can then be matched against a database if a computer or the internet is available. From a system such as this, a presumptive test can then become a much more powerful tool. Immunoassay involves the binding of an antibody that is selective for the drug or drug group of interest antigen and a label that will be part of the antibody-antigen complex that can be detected using some means such as fluorescence.

Antigen-antibody binding is based on a typical immune system response in which antibodies in biological tissue bind to antigens in order to neutralize or remove them. This technique is rarely used in drug analysis because these methods were originally designed for analysis in biological materials primarily metabolites in urine.

ELISA can, however, be used to perform other types of biochemical assays in the detection of an analyte in a liquid sample. Various opioids and cocaine can be detected rapidly and somewhat effectively using immunoassay technology.

There are problems with specificity regarding immunoassays, and there have been many instances of false positives due to similarity in drug structures or metabolites. Sensitivity is quite high with detection in the microgram range as antibody-antigen interactions occur on a molecular level [ 39 ]. Immunoassay is fast and relatively inexpensive and in most instances, does not require high-level scientific knowledge to perform and interpret.

Running such tests can require intermediate skill level. However, there is very little information available that has been scientifically published or available for public access on the usage of immunoassays for whole drug analysis. Immunoassay is most often employed to detect drug usage after the fact, such as in urine drug screens. This method has recently come under attention as a relatively cheap, easy-to-use presumptive test for fentanyl [ 40 ].

A sample of the drug sample is dissolved in water, and if the drug contains fentanyl in a concentration above the cut-off levels, an indicator on the strip will appear. To date, fentanyl is the only drug for which this method of drug checking has been reported being used [ 25 ], and there is little published data about this methodology. The provided sample is destroyed in the testing process. Urine dipsticks are very easy to use, quick to check, specific for fentanyl, proven in urine test situations, and recently been proven efficacious in testing unknown drug mixtures for the presence of fentanyl.

However, dipsticks were designed for drug detection in urine, and therefore, due to low specific weight in other mediums, it may be possible that false positives occur. Another potential concern with this method is that many retailers will only sell to health professionals, and thus, these items may be difficult to procure for harm reduction agencies unless they are affiliated with a health clinic.

Some medical device companies may object to such a test being used in a harm reduction setting, even in the presence of qualified health professionals for liability reasons. This method is based on the absorption of light energy in the ultraviolet UV wavelength range. Light in this range can raise the energy levels of the electrons within a molecule from ground state to higher energy levels.

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