Forensic Toxicology
The field of forensic toxicology (regarding dried matrix spot analysis) is divided into doping analysis and testing for illicit drugs. Hot topics at the moment are alcohol abstinence markers such as PEth and illicit drug screening options.
Doping Control
Urine is the preferred biological fluid to analyze the most commonly used performance-enhancing compounds. The collection of this biological fluid is non-invasive and cheap. However, blood testing is becoming more and more popular within the anti-doping and sports organizations, and thus the detection of forbidden substances or their metabolites in blood was included in the World Anti-Doping Agency (WADA) prohibited list [1]. Blood analysis was not convenient for large-scale screening in the past, but with new DMS methods, it will replace the urine analysis to some extent, since for certain compounds it is more accurate and non-metabolized drugs can be found. Blood analysis provides a snapshot of the compounds in the bloodstream at the moment of sampling, whereas urine reflects the degradants of the compounds used over several days. There is a tendency that more and more DMS methods will be implemented within the next years, DMS will certainly gain popularity in this market.
Illicit Drug Control
Illicit drug control is routinely performed for workplace testing, roadside testing, rehabilitation programs, screening for suspects or post-mortem investigations. Often, a drug wipe test is done, where surfaces are analyzed for traces of drug residues. This technology is non-invasive but has a high error rate. Immunoassay strips containing antibodies, which will bind to components of the different drugs [2] [3]. If those tests are positive, blood drawing at hospitals or external sites has to follow for confirmation. Usually, plasma analysis is performed to confirm or reject the first result. For post-mortem investigations, the sample goes directly to the site of analysis. With DBS sampling, such procedures are significantly accelerated and clearly more cost-effective. In addition, screening for illicit drugs within larger organizations (e.g. the military) becomes affordable. Remaining enzyme activity in collected liquid blood samples may falsify the analytical results, e.g. in direct alcohol marker measurements. Drying a sample on a DBS card immediately stops any enzyme activity and leads to reliable results.
[1] L. Tretzel, A. Thomas, T. Piper, M. Hedeland, H. Geyer, W. Schänzer, and M. Thevis, “Fully automated determination of nicotine and its major metabolites in whole blood by means of a DBS online-SPE LC-HR-MS/MS approach for sports drug testing,” J. Pharm. Biomed. Anal., vol. 123, pp. 132–140, 2016.
[2] G. Nys, M. G. M. Kok, A. C. Servais, and M. Fillet, “Beyond dried blood spot: Current microsampling techniques in the context of biomedical applications,” TrAC - Trends Anal. Chem., vol. 97, pp. 326–332, 2017.
[3] L. Mercolini and M. Protti, “Biosampling strategies for emerging drugs of abuse: towards the future of toxicological and forensic analysis,” J. Pharm. Biomed. Anal., vol. 130, pp. 202–219, 2016.