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Goldberger by Joseph 4. 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.
To ensure the specimen integrity and detecting possible adulterant, some other parameters such as, urine creatinine , pH, and specific gravity are tested along in this initial test. He had been arrested and charged after testing positive during a roadside drug test, despite not having smoked for nine days. 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 ]. Spots are then compared visually with reference charts, the current standard being the Munsell color charts. It has been technically possible to measure FAEEs since , and the first study reporting the detection of EtG in hair was done by Sachs in Although the accuracy of such tests varies with the manufacturer, some kits boast extremely high rates of accuracy, correlating closely with laboratory test results. The others will crash into the side walls and not reach the detector.
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: 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.
It is at least a decade since scientists turned their imaginations to creating new compact, portable test instruments and self-contained test kits that could be used . Download e-book for iPad: On-Site Drug Testing: Forensic Science saliva for alcohol, medicinal drugs, and their metabolites. even supposing.
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.
Each transition to a higher energy level requires a given amount of energy, provided by light of a particular wavelength. Using a particular wavelength of light, a characteristic UV absorption spectrum can be obtained based on the electronic structure of the whole molecule as this structure will determine what wavelength s are absorbed versus which pass through a sample. UV-vis ultraviolet visible spectrophotometers measure the intensity of light passing through a sample and compare it to the intensity of light before it passes through the sample and capture this information to create a characteristic spectrum.
Drugs with similar structures may provide the same UV spectra. UV-vis has been used to identify MDMA, ketamine hydrochloride, cocaine hydrochloride, diazepam, phenobarbital, and barbital concentrations in the microgram range, as well as specifically identify six different compounds and for the first time, accurately discriminate some mixtures [ 41 ]. Other substances may be identifiable although literature is sparse on confirmatory usage for a broad spectrum of illegal drugs.
UV spectrometry can be used on solid samples and therefore can be non-destructive in nature, although some samples may need preparation that can make them unsuitable for use afterwards.
UV can be used quantitatively amounts and qualitatively identification and yields rough structural information providing modest selectivity to allow for some discriminating capability [ 24 ]. UV can be combined with chromatographic techniques for greater selectivity and specificity.
It is not suitable for detection of several drugs in a mixture. Samples must be diluted or the technique can yield saturated spectra. Compounds lacking suitable chromophore provide no signal for example, GHB has a low wavelength chromophore which makes analysis by UV-vis much more difficult without further sample preparation , although most drugs of abuse have a suitable chromophore due to aromatic ring structures in their chemical structures. Additionally, UV spectrum can vary depending upon the pH of the sample solution, and it is possible for chemical composition to change during the analysis.
The level of expertise involved in UV is basic to advanced. The technique may be easily taught to someone with little to know theoretical knowledge of the technique, although interpretation of results would require intermediate to advanced knowledge. There are many variables to consider when selecting technology for drug checking on the front lines of harm reduction.
Harm reduction agencies, if pursuing the addition of drug testing services, will need to consider not only the quantitative capabilities of the tests but whether the agency can afford the human and fiscal resources to support the use of the technology. Thus, the recommendations include a strong bias to cost-benefit and beg the important question of whether some of the less discriminatory interventions are better than no intervention at all.
With these considerations in mind, the following recommendations will summarize the methods for drug testing at a point-of-care level. In most cases, quantitation is contingent on expert interpretation. In some cases, the therapeutic index is so small and such miniscule quantities can be used as an additive to mixtures that only the highest discriminatory techniques mentioned above are capable of proving unequivocally that the quantity present would fall in therapeutic index i.
In our review, the best methods for point-of-care drug testing are handheld IR or Raman spectroscopy. Manufacturers have simply made these technologies extremely easy to use and effective at identification of unknown analytes. The major downsides of this technology are that quantitation may require advanced expertise and that these units are still fairly expensive. To use these units qualitatively usually requires very little technical expertise or training. Intended for use in the field, these units are small and portable and tend to be fairly rugged, while also being able to have near-lab identification ability [ 25 ].
IMS spectrometers are very robust and require minimal maintenance. They are routinely used in airports worldwide for narcotics detection. Training is easy and quick, and sensitivity and selectivity are very high. Consumables are cheap and have long lives.
Sampling is non-destructive and quantification is possible without expert level understanding. Analysis is quick and accurate. IMS is the best option available for clinics with a moderate level of funding. Some gas analyzers allow online updating; rapid sample analysis of liquid, solid, and gas; and discrimination of multiple interfering species in a complex matrix.
The capability to update online allows methodologies and new molecular species to be shared instantly among clinics enabling point-of-care testing to remain current. MS is considered the current gold standard in forensic drug analysis. Since MS units have been in use for a long time, it is actually possible to obtain one for a decent price low-to-mid thousands in the used market. However, in order to obtain a newer device optimized for drug testing or for testing extremely low concentrations, it would come with a higher price tag, usually in the hundreds of thousands of dollars.
This presents a difficulty of its own because of the wide range of machines available, it would take some considerable research at clinic level to determine the cost-benefit analysis of a new or used machine to ensure acquisition of a machine that is suitable for its intended purpose. UV spectroscopy and TLC are more affordable options, but also much less discriminatory. Both of these methods tend to be less technical in operation, maintenance, and interpretation of results, but also do not offer quantification at the same level of the more discriminatory methods.
They are also less expensive than all of the more discriminatory techniques. However, when used in conjunction, TLC and UV can be quite powerful in identification of a wide variety of substances including mixtures and offer a more rudimentary quantification than the more discriminatory techniques. Information about optimal technique can be easily accessed via the internet.
Color tests are cost effective, fast to complete, and very easy to perform. The use of a smartphone app can aid in identifying the exact color profile. This can then be used in conjunction with a searchable database to perform the most accurate identifications. The fact that this technology is so cost-effective, easy to perform, and requires a very minute amount of substance makes it really stand out from many of the other presumptive methods [ 16 ].
This type of test is widely used in Europe [ 16 ]. These tests are not perfect and can be performed incorrectly. A proper standardization of technique should be implemented at the clinic level to maximize the accuracy of these tests. Drug testing methods that are less suited to point-of-care drug testing situations include immunoassay, microcrystalline testing, and X-ray diffractometry. Immunoassays are traditionally designed for usage in biological samples as they work based on antibody-antigen interactions and as such are best suited for testing excreted metabolites such as in urine.
At best, an immunoassay can indicate the presence of drug s , and at worst, they can give a high proportion of false positives. This may result in people using the substances anyways or serve to give the clinic a poor reputation, and users may soon stop going to the site for drug testing. That said, they are affordable and portable and can detect potentially fatal drugs like fentanyl.
Microcrystalline testing is a highly limited method as the drug needs to be mostly or completely pure. This testing has no quantification capabilities at all and requires high skills and knowledge to identify drugs based purely on crystal structure. X-ray diffractometers are incredibly expensive mid-to-high tens of thousands , difficult to maintain and operate, and have the added factor of using radioactivity which may present health and safety concerns.
Each of these techniques has a variety of associated pros and cons that must be considered. With this in mind, this review is not meant to be an in-depth rigorous scientific treatment of each of these methods, but a guide for the practical consideration of usage and recommendations for point-of-care harm reduction purposes. It is sincerely expected that this document will help to narrow down consideration of each of these techniques and that each clinic would then determine a smaller subset of techniques to consider implementing.
It would be prudent for clinics that can obtain the funding to contact the companies who produce and design these devices and discuss possible usage in a harm reduction setting as many of the devices are only currently in use in law enforcement and research. LH analyzed the extant literature, creating the basis for the paper.
JP offered technical analysis and editorial support. EP worked with LH to make the text suitable to a non-technical audience. All authors read and approved the final manuscript. He is currently enrolled in a second degree program and participating in research in Biochemistry at the University of Lethbridge.
Lane is also interested in the politics of sensible drug policies and associated programs, including, but not limited to, the implementation of harm reduction best practices in Canada. He currently works on automation and sensing technology. EP holds degrees in nursing and is an assistant professor in the Faculty of Health Sciences at the University of Lethbridge. EP has a clinical background in outreach nursing and harm reduction and conducts research and evaluation studies with local harm reduction agencies.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. National Center for Biotechnology Information , U. Journal List Harm Reduct J v. Published online Jul Author information Article notes Copyright and License information Disclaimer. Received May 26; Accepted Jul This article has been cited by other articles in PMC. Abstract Given the current opioid crisis around the world, harm reduction agencies are seeking to help people who use drugs to do so more safely. Harm reduction, Substance abuse, Street drugs, Drug overdose, Drug users, Drug effects, Drug-related side effects and adverse reactions, Drug evaluation.
Background Given the current opioid crisis in Canada [ 1 — 3 ] and around the world [ 4 ], harm reduction agencies are seeking to help people who use drugs to do so more safely. Table 1 Summary of drug testing technologies and methods, and definition of terms. Open in a separate window. Most discriminatory Mass spectrometry How does it work? What substances can be detected and how accurately? How easy is it to use? Ion mobility spectrometry How does it work? Infrared spectrometry How does it work? Raman spectroscopy How does it work?
X-ray diffractometry How does it work? Least discriminatory Microcrystalline tests How does it work? Thin-layer chromatography How does it work? What substances can be detected, and how accurately? Immunoassay How does it work? Urine dipstick test This method has recently come under attention as a relatively cheap, easy-to-use presumptive test for fentanyl [ 40 ]. Ultraviolet spectroscopy How does it work? Conclusion There are many variables to consider when selecting technology for drug checking on the front lines of harm reduction.
Availability of data and materials NA. Ethics approval and consent to participate NA. Consent for publication NA. Competing interests The authors declare that they have no competing interests. Contributor Information Lane Harper, Email: Deaths involving fentanyl in Canada, — Canadian Centre on Substance Abuse; Canadian Institute for Health Information. Hospitalizations and emergency department visits due to opioid poisoning in Canada.
Accessed 16 Mar The drug situation in Europe: Executive Agency for Health and Consumers.
Factsheet on drug checking in Europe. An inventory of on-site pill-testing interventions in the EU: Drug checking to improve monitoring of new psychoactive substances in Australia. J Am Pharm Assoc. Misrepresentation of stimulant street drugs: J Toxicol Clin Toxicol. Street drug analysis and its social and clinical implications. University of Toronto; Sage C, Michelow W. Drug checking at music festivals: Standing Committee on Health. House of Commons; Interim report and recommendations on the opioid crisis in Canada.
Drug checking and pill testing—what it can and cannot do and why it matters. Accessed 28 June Drug testing in Europe: Drug-testing technologies and applications. Direct analysis in real time DART mass spectrometry. Accelerator mass spectrometry in the attomolar concentration range for 14 C-labeled biologically active compounds in complex matrixes. J Anal At Spectrom. Reliability of ion mobility spectrometry for qualitative analysis of complex, multicomponent illicit drug samples.