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Advances in Forensic Toxicology
Ellen Mizio, MSLS, NCSTL Fellow

Scientists are constantly researching new methods to identify the presence of drugs and other substances more rapidly and efficiently. They also continue to seek ways to use different types of biological samples for analysis, with the goal of quicker results and less invasive methods of collecting samples. This article discusses new methodologies in the field of forensic toxicology, as well as the use of different types of samples to identify exposure to drugs.

Methodologies

The availability of Liquid Chromatography/Mass Spectrometry (LC-MS) is one of the most significant advances in forensic toxicology in recent years. LC-MS is now available at affordable prices and allows screening and confirmation of a much larger range of analytes than can be covered by combined immunoassay and gas chromatography-mass spectrometry. Tandem LC-MS allows more specificity in results and smaller detection limits, allowing very small sample sizes to be used. Forensic laboratories are increasingly using these instruments because of lower costs, decreased staff time, and better analysis.1

In her thesis "Forensic Applications of Differential Mobility Spectrometry" Samantha Mosley identifies a new technique for detecting the hallucinogen Salvia divinorum. Typically forensic labs use Gas Chromatography/Mass Spectrometry (GC/MS) to identify Salvia divinorum, a process which takes about 30 minutes. The technology of Differential Mobility Spectrometry (DMS) is used for gas phase ion separation, and when paired with mass spectrometry offers many improvements in ion separation. Rapid ion separation allows quick identification of the desired ions, taking less than one minute to identify specimens.2

Another new technique involves coupling a gas chromatograph (GC) with an isotope ratio mass spectrometer (IRMS) in parallel with a single quadrupole mass spectrometer (MS). Samples of cocaine and marijuana were analyzed using this method in order to determine if samples came from the same source.3

Alternative methods based on liquid chromatography tandem mass spectrometry (LC-MS/MS) have been studied for use in the detection of ketamine and amphetamines in biological specimens. Previously most methods for the detection of these drugs used gas chromatography mass spectrometry (GC-MS). The study used these techniques: enzyme-linked immunosorbent assay (ELISA), liquid chromatography tandem mass spectrometry (LC-MS/MS) and molecularly imprinted polymer solid phase extraction (MISPE). MISPE is a new extraction technique in forensic toxicology applied to biological samples. The MISPE and SPE methods were combined with Liquid Chromatography Electro-Spray Ionization Mass Spectrometry (LC–ESI-MS) to detect ketamine, norketamine and amphetamines in urine, whole blood and hair samples. This method was found to be easy to use, and researchers were able to detect lower concentrations of drugs with this method.4

Another new method that has been studied is the use of liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) in the analysis of opioids, delta-9-tetrahydrocannabinol (THC) and metabolites, barbiturates, and acidic drugs, in an effort to develop less time consuming methods for identifying drugs in postmortem blood and urine samples. The study resulted in quicker extraction methods for detecting opioids, THC, and two THC metabolites. In the case of barbiturates and acidic drugs, it was found to be possible to do analysis using LC/MS/MS, but greater specificity was achieved by using GC/MS (gas chromatography/mass spectrometry) to analyze these types of drugs.5

Types of Specimens/Samples

In addition to new methods for identifying drugs and other substances in biological samples, researchers also continue to develop ways to use different types of biological samples to gain more information, rather than just having to rely on one type of sample that may be difficult to obtain.

Fingerprints The British company Intelligent Fingerprinting (http://www.intelligentfingerprinting.com/index.html) has developed technology that "uses a substance that reacts with molecules excreted in the sweat that makes up fingerprints to confirm the presence of a drug." The device operates by coating the fingerprint in a solution of antibody-covered particles, using a microfluidic system. The particles change color when the antibodies bind with molecules of a drug or drug metabolites. The body produces these when drugs are ingested, and then the metabolites are excreted in fingerprints through sweat. The company has developed the process for use in the lab and is currently working on plans for a device that could be used by crime scene officers to immediately determine if drugs are present in a fingerprint.6

Oral Fluid (Saliva) Progress has been made in detecting substances in oral fluid (saliva), rather than just from urine samples. Testing oral fluid is non-invasive and potentially eliminates adulterated samples, and samples can be collected under direct observation without regard to gender. Forensic Laboratories in Denver has developed a test capable of detecting Ethyl Sulfate (EtS) in saliva. EtS is a chemical produced by the body after alcohol exposure. The test method also detects Ethyl Glucuronide (EtG). It has been suggested in some scientific publications that EtG and EtS can be detected for a longer period of time than ethanol. The presence of EtG tests whether or not alcohol has been used, not for current impairment.7 Forensic Laboratories has also developed an oral fluid test for Tapentadol, a new FDA approved drug for pain management. Previously the drug could only be detected through liquid chromatography-mass spectrometry-mass spectrometry (LC/MS/MS).8

Redwood Toxicology Laboratory in California has developed an oral fluid test to detect the presence of synthetic marijuana, which has become widely used. Previously methods had been developed to test for the substance in urine.9

Oral fluid analysis has also been used for detection of marijuana. The process has been tested using high-throughput GC-MS/MS confirmation and quantitation of A9-THC in oral fluids, as well as the method of solid phase extraction (SPE), due to its ease-of-use and the untainted nature of the consequent extracts. A MRM (multiple research monitoring) method on a GC-triple quadrupole MS was also used. The conclusion was that this method "to confirm and quantitate THC in oral fluid is an effective alternative to blood and urine samples."10

Hair Matrix-assisted laser desorption ionization (MALDI)–time-of-flight (TOF) mass spectrometry (MS) has recently been used to detect methamphetamine in human hair. This imaging MS method seems to result in more accurate chronological information on drug use, and also is able to better determine the difference between passive exposure to the drug and deliberate use. This is the first time imaging MS technology has been used in a forensic toxicological context.11

New Drugs/Substances

Forensic toxicologists are also continually challenged by new drugs or substances that are developed, and methods to detect these substances must be developed. "Designer drugs", which are typically created by altering the molecular structure of existing drugs, in order to avoid drug laws, are constantly being created. Synthetic cannabis has become one of the most popular types of these drugs. Often it is marketed for sale as "herbal incense". The process of identifying these substances can be very difficult, because the analysis results in complex chromatographic data; also, there has been little reference material to use for positive identifications. Agilent Technologies and NMS Labs have collaborated to develop a method to identify these compounds, using gas chromatography/mass spectrometry (GC/MS).

Conclusion

Scientists and researchers will continue to work on developing new ways of identifying exposure to drugs and alcohol, in order to assist with medical and legal investigations of deaths and crimes. As new drugs are developed, they will also work on tests to identify these drugs and other substances.

Up
1  Drummer, Olaf H.., Dimitri Gerostamoulos, and Jochen Beyer. "Drug Testing Development." Forensic Technology Review. 2010: 161. 06 July 2011. http://www.forensics-news.com/2010review.
2 Mosley, Samantha. "Forensic Applications of Differential Mobility Spectrometry." MS thesis Northeastern U, 2010. Web. 06 Jul. 2011.
3 Muccio, Zeland. "Isotope Ratio Mass Spectrometry - A Rapidly Developing Tool for Forensic Samples." Diss. Ohio U., 2010. Web. 06 Jul. 2011.
4 Harun, Norlida. "Application of Molecularly Imprinted Solid Phase Extraction, Enzyme-Linked Immunosorbent Assay and Liquid Chromatography Tandem Mass Spectrometry to Forensic Toxicology." Diss. Glasgow U. Web. 11 Jul. 2011.
5 Herrin, George, et. al. Enhanced Studies of LC/MS/MS Capabilities to Analyze Toxicology Postmortem Samples. 2010. Web. 06 July 2011. Harris, Stephen. "Fingerprint Device Could Detect Illegal Drug Use." The Engineer. 20 Sept. 2010: 2P. 07 July 2011. . Web. 06 July 2011. http://www.theengineer.co.uk/fingerprint-device-could-detect-illegal-drug-use/1004899.article#ixzz1Qm14Vocc.
6 "Forensic Laboratories Develops First Oral Fluid Test for Ethyl Sulfate Detection." Biotech Week. 18 Aug. 2010: 582. 07 July 2011. http://www.laboratorynetwork.com/article.mvc/Forensic-Laboratories-Develops-First-0001.
7 "Forensic Laboratories Develops First Oral Fluid Test for Tapentadol." Drug Week. 02 Apr. 2010: 3609. 07 July 2011. http://www.prnewswire.com/news-releases/forensic-laboratories-develops-first-oral-fluid-test-for-tapentadol-87645572.html.
8 "Redwood Toxicology Laboratory Announces Oral Fluid Test for Synthetic Cannabinoids: JWH-018, JWH-073 and JWH-250." FreshNews.com. 15 Nov. 2010. 07 July 2011. a href="http://www.freshnews.com/news/414087/redwood-toxicology-laboratory-announces-oral-fluid-test-synthetic-cannabinoids-jwh-018-.
9 Chi, Eric, and Jason Cole. "Detecting Marijuana In Saliva." Forensic Magazine. Oct.-Nov. 2010: 07 July 2011. http://www.forensicmag.com/article/detecting-marijuana-saliva.
10 Miki, Akihiro, et al. "Imaging of Methamphetamine Incorporated into Hair by MALDI-TOF Mass Spectrometry ." Forensic Toxicology. July 2011: 111. 07 July 2011. http://www.springerlink.com/content/03395044421mq043/.
11 Gluodenis, Thomas J. "Identification of Synthetic Cannabinoids in Herbal Incense Blends." Forensic Magazine. June-July 2011: 07 July 2011. http://www.forensicmag.com/article/identification-synthetic-cannabinoids-herbal-incense-blends.