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Drug Detection at Your Fingertips: Illicit Drugs in Fingerprint Sweat
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Drug Detection at Your Fingertips: Illicit Drugs in Fingerprint Sweat

Researchers have developed a new tool for the rapid detection of a number of illicit drugs using only the sweat of an individual’s fingerprint.

Typically, the procedure to test for drugs in human beings necessitates the collection of blood or urine and laboratory-based analysis by gas or liquid chromatography with mass spectrometry. Unfortunately these standard methods are somewhat invasive, require potentially time-consuming laboratory-based analysis, and use complex pieces of analytical instrumentation requiring a trained operator to use. They are inevitably unsuitable for rapid, in-situ screening of potential drug users.

Researchers at the University of East Anglia and Intelligent Fingerprinting Ltd (a spin-out company from the university) have been working on a method of conducting simple, rapid drug analysis using sweat from a person’s finger. The technique has been developed to detect four classes of drugs – cannabis, cocaine, amphetamines and opiates, with cannabis being detected based on the presence of Δ9-tetrahydrocannabinol (THC), cocaine on the presence of benzoylecgonine, and opiates via the detection of morphine.

The finger of an individual is firmly pressed onto the Drug Screening Cartridge. This is then filled with a buffer solution before insertion into the reader for analysis. Capable of detecting drugs down to the picogram level, the system is a fluorescence-based lateral flow competition assay containing four drug-bovine serum albumin conjugate lines on a nitrocellulose test strip.  In short, when a sample is introduced to the test strip, fluorescently-tagged antibodies pass over the conjugate lines. As these antibodies are specific to each drug class of interest, if that drug is present they will bind to the drug. At the end of the test, a fluorescence signal is measured. If none of the four drug classes were present, a maximum fluorescence signal will be obtained. However if any drugs were present to bind with the antibodies, there will be a decrease in the fluorescence signal proportional to the drug concentration. Within about 10 minutes, the device then gives a simple pass/fail response, requiring no specialist knowledge or excessive training to operate and interpret the results.

Furthermore, the technique has also been demonstrated to be effective when applied to the deceased. Researchers worked with a number of UK-based coroners to obtain fingerprint sweat samples from 75 deceased individuals. The most common drug detected was opiates, which is a logical finding considering the number of terminally ill patients who are prescribed morphine during palliative care.

In order to compare the new technique with those typically employed in the detection of drugs in human beings, analysis of blood samples was conducted by LC-MS-MS. The results between the two methods correlated well, with the accuracy between DSC of fingerprints and LC-MS-MS of blood being 88-97%, depending on the drug. This demonstrates the effectiveness of the method and its ability to stand up to existing techniques, though there are inevitably some shortcomings. Authors of the study have stated that there are known accuracy issues with lateral flow measurement devices, thus this new technology should be used as a presumptive screening method prior to confirmation by mass spectrometry. Furthermore, the range of target drugs is clearly currently limited, though future development could no doubt enable other classes of drug to be included.

Full details of the findings can be found in the Journal of Analytical Toxicology.

 

References

Hudson, T. Stuchinskaya, S. Ramma, J. Patel, C. Sievers, S. Goetz, S. Hines, E. Menzies and D. A. Russell, J. Anal. Toxicol., 2018, 6–10.

Forensic Magazine. Fingerprint Drug Screen Test Works on the Living and Deceased. [Available online] https://www.forensicmag.com/news/2018/10/fingerprint-drug-screen-test-works-living-and-deceased

 

Forensic Failures: Philip Scott Cannon & Bullet Analysis Blunders
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Forensic Failures: Philip Scott Cannon & Bullet Analysis Blunders

In December 2009, Philip Scott Cannon of Polk County, Oregon was released from prison after his conviction was found to be based on ‘junk science’. By this time, he had served over 10 years.

The story of his wrongful imprisonment began on 23rd November 1998, when Bimla Boyd noticed that the mobile home of a neighbour appeared to be on fire. Upon investigating, she discovered the bodies of three people; Jason Kinser, his girlfriend Suzan Osborn, and Celesta Graves. All three victims had been shot. Boyd promptly called the police, and a murder investigation ensued.

Boyd stated that earlier in the day she had noticed a maroon van parked nearby, a van which happened to belong to Philip Scott Cannon. Around the same time, local men Jeremy Olsen and Larry Weaver were on their way to deliver water to the victims’ trailer. Upon arrival at the trailer, Olsen and Weaver claimed that they were met by Cannon, who was said to be “acting strangely”. Cannon informed the men that they should not go into the trailer because Jason Kinser was upset and in the midst of a heated argument with an unknown Hispanic man. Olsen and Weaver subsequently left without entering the trailer. Based on this eyewitness testimony and the fact that Cannon owned the maroon van spotted nearby, he soon became the prime suspect.

Credit: Polk County Itemizer-Observer

When questioned by police, Cannon maintained his innocence and claimed Kinser had called him over to give an estimate for fixing a plumbing problem in the trailer, after which he promptly left when Kinser began arguing with another man. However the police had a very different impression of the situation, believing that Cannon was a meth user and Kinser his dealer. Further suspicion fell on Cannon when a prisoner, Steven Brobston, informed police that he had entrusted Cannon with a box containing $16,000 to be used to support Celesta Graves, Brobston’s girlfriend and one of the victims. With the circumstantial evidence mounting, investigators searched Cannon’s home, finding the lockbox but no sign of the money. They did however stumble upon a number of weapons and ammunition. This was sufficient to arrest Cannon, who was taken into custody on 3rd December and charged with three counts of aggravated murder and the illegal possession of a firearm.

During the trail, Olsen, Weaver and Boyd were all called upon to recount their experiences of seeing Cannon near the trailer on the day of the murder. Of course this evidence was purely circumstantial, so an expert witness was called upon to study the bullets collected from the crime scene and those recovered from the suspect’s home. Michael Conrady of Oregon State University’s radiation center conducted a metallurgic analysis of the bullets known as comparative bullet lead analysis. This technique involves the application of various analytical techniques, but primarily atomic emission spectroscopy, to bullet composition determination. The method aims to establish the composition of metals in the bullet, such as copper, tin, antimony and silver, and compare profiles to ascertain whether two bullets are chemically identical. Based on this analysis, Conrady testified that the bullets from the crime scene and those from Cannon’s home were chemically identical, therefore Cannon’s ammunition was used to kill the three victims. However the weapons found in Cannon’s home were not connected to the murders, nor did police establish a reasonable motive for the triple homicide. Despite these shortcomings, on 28th February 2000, Cannon was found guilty and sentenced to three life sentences with no parole.

At the time of Cannon’s trial, the use of comparative bullet lead analysis was already under scrutiny, with some believing the reliability of the technique was unfounded. In 2005, the national Academy of Science discredited the technique and deemed it ‘junk science’, and soon after the FBI abandoned the use of this method altogether. As Cannon’s conviction was so heavily reliant on the bullet analysis, in 2009 a Polk County Circuit judge vacated Cannon’s original conviction. Incidentally it was now apparent that police involved in the original trial had hired Conrady to conduct the bullet analysis because the Oregan State crime lab had refused on the basis of the technique being scientifically unreliable. In order for a re-trial to take place, the original bullets were demanded in order to conduct further analysis. Polk County prosecutors insisted that the original trial evidence had been sent to the Department of Justice when Cannon had appealed his conviction, however Assistant Attorney General Susan Gerber, who had been assigned the case, claimed she had never received this evidence. It later came to light, when Gerber was suspended from her position on assault charges, that she had had the evidence all along, locked away in a filing cabinet.

In light of all of this, Cannon’s conviction was dismissed and he was released from prison. By this point he had spent over a decade behind bars. No other arrests have been made in relation to the murder of Kinser, Osborn and Graves.

 

References

Michigan State University National Registry of Exonerations. Philip Scott Cannon. [Available online] https://www.law.umich.edu/special/exoneration/Pages/casedetail.aspx?caseid=3083

Photo Credit: Polk County Itemizer Observer. Cannon retrial up to Polk DA. [Available online] http://www.polkio.com/news/2011/oct/25/cannon-retrial-up-to-polk-da

 

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Interview with Program Director Max Houck

What is your current job role and what does this position involve?

My current role is Visiting Assistant Professor and Director of the Forensic Studies & Justice Program at University of South Florida St. Petersburg. The Program teaches forensic investigative techniques and scientific applications in criminal cases, using structured analytic techniques borrowed from the intelligence community to mitigate and reduce bias, and how to improve the criminal justice system and avoid wrongful convictions. I created the Program, teach in it, and conduct research in these areas.

How did you come to work in the field of forensic science?

I became interested in forensic science through taking anthropology courses for my undergraduate minor; I was originally in International Relations and was going to be a translator (Russian and Japanese). Ultimately, bones made more sense than conjugating irregular Russian verbs and I changed majors. In my Masters work, I was a student of Jay Siegel, who set me on my path to a forensic science career.

What would you say has been the highlight of your career to date?

Being Director of the Washington, D.C. Department of Forensic Sciences. I structured the new agency, created many of its new policies for independent science, and worked with people who remain my heroes for what they do.

During your years working in forensic science, how do you feel the field has changed?

I worry that the field has become a bit of a cargo-cult science–we’ve “drunk our own Kool-aid”, as the saying goes. We believe if we SAY something is “scientific”, then it IS scientific. We’ve also come up with some fairly suspect ways of justifying bad or marginal science and these have been accepted by an all-too-willing court system. That is beginning to change, a little, with some good basic research into the fundamentals of our science but we’re still hampered by trying to be the servant of justice instead of a partner in the process.

In recent years, concerns over the reliability of some forensic techniques have been raised in the media. What steps do you think we need to be taking to ensure that only scientifically reliable techniques are utilised in legal investigations?

First and foremost, forensic agencies need to be independent of law enforcement; that won’t solve everything but it’s a good start to ensure we’re not marginalized. Second, we need to stop worrying about new methods and shore up the ones we’re already using–do they work and, if so, how well? Finally, we have to be better communicators about what we can and cannot say and why. Being pressured by money, time, or politics only gets you shoddy results–just look at any of the latest “forensic failures”.

Finally, do you have any words of wisdom for those pursuing a career in forensic science?

Be a scientist first; the application to criminal cases can come later. Don’t job hop; keep your first job at least two years and then move up or out. And last, don’t worry about ethics, worry about integrity. Ethics is knowing right from wrong and prisons are full of people who know the difference, they just lacked the integrity to make the right choice.

 

Sweat Security: Using Skin Secretions for Authentication
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Sweat Security: Using Skin Secretions for Authentication

The use of passwords and pin numbers is part of our daily lives, being a necessity in ensuring our data and money doesn’t fall into the wrong hands. However passwords and pattern-based pins have their obvious limitations, and they are only as secure as the user is cautious.  One method of improving security utilises biometric technology, which is based on the biological or behavioural characteristics of an individual. Biometric-based security systems are certainly nothing new. The concept of using fingerprints, retinal scans and voice recognition as security measures materialised decades ago, and such techniques are frequently used for authentication purposes. Despite these technological developments, ongoing research is attempting to develop more robust and secure methods of identification.

Researchers at the University of Albany are developing a unique new technique of biometric identification using only a person’s sweat. Human sweat, and all body fluids for that matter, contains a plethora of chemical compounds, ranging from small weight molecules to large proteins. These compounds originate from a variety of sources, with some resulting from endogenous metabolic processes within the body, and others being introduced through diet and environmental exposure. Metabolite levels can be affected by an endless array of factors, including sex, ethnicity, age and lifestyle. Interestingly, it is now known that the presence and amount of some of these compounds can vary greatly between different people, thus in theory unique metabolome profiles could be harnessed for identification purposes.

phone

The compounds the technique will focus on is vital, as certain chemical levels can fluctuate wildly throughout the day depending on what we have eaten, for instance. However levels of certain chemicals have been found to be relatively stable or at least only vary gradually. In this research, Assistant Professor Jan Halámek and his team focused on using amino acid profiles of sweat to offer a unique means of authentication.

By first establishing which amino acids are present in a person’s skin secretions, a wearable device can then be constructed which will monitor the levels of these compounds. The device would initially require a kind of enrolment period, during which time the user’s skin secretions would be constantly measured in order to develop a unique profile of metabolites. It is already known that the metabolites released by the body vary throughout the day, so such a monitoring period would be necessary to take into account these changes.

Over time a profile of the user’s skin secretions would be built up and stored within the device, acting as a kind of standard for comparison. When future skin secretions are analysed by the device, the profiles will be compared with the known user profile and used to confirm the identity of the user. In the event of anyone else picking up the device, the instrument would detect a different skin secretion profile and lock the device or turn it off, thus ensuring security of the smartphone or computer.

If successful, the technology could offer an improved active authentication system, either as a standalone system or supplementing existing technology. However the technique is very much in its infancy and a great deal more research will be required before this kind of technology is rolled out commercially, if it ever is possible. It is likely that such a technique will be affected by contamination, for instance as the user’s hands become dirty throughout the day or if cleaning or cosmetic products are applied to the skin. Furthermore, if authentication is based on comparison with an electronically stored profile, the device may still be susceptible to hacking in order to bypass the security system. But if this technique could reach a sufficient level of robustness, the days of struggling to remember your password could be eliminated.

 

Agudelo, J. Privman, V. Halamek, J. Promises and Challenges in Continuous Tracking Utilizing Amino Acids in Skin Secretions for Active Multi-Factor Biometric Authentication for Cybersecurity. ChemPhysChem. 18, 1714-1720 (2017).

Tracking Illicit Drugs with Strontium Isotope Analysis
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Tracking Illicit Drugs with Strontium Isotope Analysis

The manufacture and distribution of illicit drugs such as heroin is a primary focus of many major law enforcement organisations worldwide, including the Drug Enforcement Agency (DEA) in the United States and the National Crime Agency (NCA) in the United Kingdom. Unfortunately, as drug shipments pass hands between dealers and cross borders so rapidly, it can be difficult if not impossible to trace a batch of drugs back to an initial manufacturer. As a result of this, the chances of locating and arresting the manufacturers of illicit drugs can be slim.

To a forensic drugs analyst, a whole range of characteristics can be examined and used to classify and compare different batches of the same drug, including physical appearance, packaging, and chemical composition. To an extent, heroin chemical signatures are already beneficial in comparing different batches of the drug in attempts to establish links and possible sources of the narcotics. This may be based on agents or adulterants a product has been cut with, and the relative concentrations of those substances. The manufacturing process itself can vary in terms of chemicals and apparatus used and the skills of the manufacturer, resulting in further characteristic differences in the chemical profile. However these differences may not be distinct enough to be valuable and are certainly not able to pinpoint the country from which a batch originated. Though there is still no reliable method of tracing an illicit drug back to a particular location, ongoing research is aiming to change this.

One method of studying the history and even origin of a sample is to use isotopic composition. Isotopes are different forms of elements that are incorporated into substances in the environment in varying ratios and abundances, influenced by a number of factors that can alter these ratios. These processes can be described as isotopic fractionation. Interestingly, isotopic ratios can be characteristic to different regions of the world, enabling certain materials to be traced back to the geographic region based on the ratios of particular isotopes contained within that material. With this in mind, they have often been used to trace unidentified human remains to a particular location or study the origin of food products. Focusing on isotopes allows for heroin samples to be studied and compared based on regional characteristics as oppose to the variation caused by the production process.

For the first time, researchers at Florida International University have utilised strontium isotope ratio analysis to determine the provenance of illicit heroin samples. 186 unadulterated, undiluted heroin samples of known origin were obtained from a number of geographic regions including Southeast Asia, Southwest Asia, South America, and Mexico. Of a particularly challenging nature is South American heroin and SA-like Mexican heroin, which can be extremely difficult to differentiate based on their chemical compositions alone. Heroin samples were dissolved via a microwave-assisted acid digestion method before being subjected to a technique known as a multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS). This instrument utilises an inductively coupled plasma ion source to ionise target analytes, which are then separated and analysed by the mass spectrometer. The use of MC-ICP-MS allows for the strontium concentration of particular samples to be determined. The strontium isotope ratio (87Sr/86Sr) value of each individual sample was then compared with the overall mean values of ratios from different regions in order to establish the likely origin of that particular heroin sample. Samples from the same geographic region would be expected to exhibit a similar isotope ratio.

icpms

Multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) Source: www.thermofisher.com

The results demonstrated the possibility of differentiating between heroin of different geographic origin. South American and Mexican heroin samples were correctly classified 82% and 77% of the time respectively. South East and South West Asian heroin samples were somewhat more difficult to differentiate due to more of an overlap between strontium isotope ratio values. SE Asian samples were correctly classified 63% of the time and SW Asian samples only 56% of the time. It is not clear whether this elemental strontium is endogenous or the result of external contamination, but either way it is sufficiently characteristic to be associated with a particular geographic location.

The strontium isotope composition of heroin can be affected by a number of factors, including the soil in which components are grown and groundwater in the area, which can result in region-specific isotope compositions. The use of strontium isotope ratio analysis has presented promising results in the origin determination of illicit heroin. Although a larger scale study incorporating samples of a more worldwide origin would be ideal, initial results suggest that this technique could allow for an unknown illicit drug sample to be traced back to a country of origin, aiding criminal intelligence agencies in the war against drugs.

 

Debord, J., Pourmand, A., Jantzi, S., Panicker, S. & Almirall, J. Profiling of Heroin and Assignment of Provenance by 87Sr/86Sr Isotope Ratio Analysis. Inorg Chim Acta. In press (2017).

Instant Insect Identification to Aid Forensic Entomology Investigations
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Instant Insect Identification to Aid Forensic Entomology Investigations

During the investigation of a suspicious death, entomological (that is, insect-related) evidence may be able to provide vital clues as to when the victim died. Determining time since death, or post-mortem interval, can be one of the most important aspects of such an investigation, so it comes as no surprise that a great deal of research has been directed towards improving these estimations.

Insects can play a huge role in estimating time since death. Various types of species of insect will often visit the scene of a death in a relatively predictive manner, either to feed on the decomposing remains (known as necrophagous insects), to prey on other insects present, or to find a suitable place to lay their eggs. Blow flies, a group which includes common flies such as the bluebottle and the greenbottle, are often of particular interest. Forensic entomologists will typically study the insects, eggs and larvae present at a death scene, utilising the type of bugs found and their stage of development to track back to the likely time at which they arrived, thus when the victim may have died. However in order to accurately do this, entomologists must often collect insect specimens for closer inspection and even to rear to adulthood in order to determine the exact species, which is evidently a time-consuming process requiring a high level of expert knowledge.

For the first time, researchers at the University of Albany have applied a technique called direct analysis in real time with high resolution mass spectrometry, or DART-HRMS for short, to the analysis of blow fly eggs. Published in the latest issue of the journal Analytical Chemistry, the technique has demonstrated the possibility of almost instantly differentiating between different fly species based on the amino acid profiles of the eggs.

DART-MS, developed in 2005 by Dr Chip Cody of JEOL, is an ambient ionisation mass spectrometry technique that allows for samples to be directly analysed without any time-consuming sample preparation steps, and perhaps most importantly without destroying the sample. The sample is simply presented in its native state between the ion source and the inlet of the mass spectrometer, enabling compounds present in the sample to be ionised and drawn into the instrument for analysis and identification.

dartms

Sampling interface of DART-MS. Source: Wikimedia Commons

During this investigation, researchers used pieces of pork liver to attract a number of different blow fly species before transporting them to the laboratory. The flies were reared until they lay new eggs, which would be the focus of the analysis. The study utilised specimens of a number of species, including Calliphora vicinia, Lucilia coeruleiviridis, Lucilia sericata, Phormia regina, along with specimens from the Phoridae and Sarcophagidae families. Even to the eye of an expert, the eggs of these specimens are often indistinguishable. The eggs were simply placed in an ethanol solution and the mixtures directly subjected to DART-HRMS analysis.

The technique focused on the analysis and identification of amino acids in the eggs, essentially enabling researchers to produce a chemical fingerprint unique to eggs of a particular species. Examination of the mass spectra showed that the different species exhibited a unique chemical fingerprint, and by using multivariate analysis it was possible to better visualise the similarities and differences between amino acids detected in the eggs of different species.

Unsurprisingly, many amino acids were common to multiple species. For instance, alanine, isoleucine and proline were detected in four of the species, whereas valine was detected in all but one of the egg samples. However some compounds were unique to particular species, and it is these unique amino acids that will prove to be most beneficial in differentiating between the eggs of different species. For instance, glutamine and tryptophan were only present in the eggs belonging to P. regina. Interestingly, the research also demonstrated the ability to distinguish between families as well as species, with some compounds only detected in the eggs of specific families.

By using this particular technique, almost instantaneous identification could be achieved. Of course this research has included only a very limited number of species, thus a much bigger investigation would be necessary before the technique would really be beneficial to a legal investigation. Not only would further species need to be included, but another potential development would be the production of a chemical profile database against which unknown insect samples could be compared. Developed further, the use of DART-MS could save investigators a lot of time in the identification of insects of forensic interest.

 

References

Cody, R. B., Laramée, J. A. & Durst, H. D. Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions. Anal. Chem. 77, 2297–2302 (2005).

Giffen, J. E., Rosati, J. Y., Longo, C. M. & Musah, R. A. Species Identification of Necrophagous Insect Eggs Based on Amino Acid Profile Differences Revealed by Direct Analysis in Real Time-High Resolution Mass Spectrometry. Anal. Chem. (2017) In Press

 

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Interview with Forensic Physician Samar Abdel azim Ahmed

samar

What is your professional background in forensic science?

I am an associate professor of Forensic Medicine in Ainshams University Faculty of Medicine in Egypt. I received my doctorate degree 10 years ago with honours from ASU and then proceeded to work on my educational capacity. I studied for a second Masters degree from Maastricht University and Suez Canal University in Health professions education. I then received a scholarship from ECFMG in USA for a fellowship program in Health professions education in FAIMER, Philadelphia.

What is your current job role and what does this work involve?

Currently I teach forensic Medicine to fourth year medical students together with my administrative job as the director of the Centre of Excellence in Forensic Psychiatric research. This centre is a product of a Newton Mosharafa Fund that I received from the British council and the Science Technology Development fund in Egypt to establish forensic psychiatry research trends in Egypt. At the moment I am working on establishing partnerships within the scope of forensic psychiatric service improvement.

What initially attracted you to this field of work?

I am a physician by training but I was attracted to the field of forensics mainly challenged by the importance of the service that one can offer to justice by giving a voice to the voiceless. My work as a forensic physician is mainly to advocate for those who are victimized and to prevent further injustice by uncovering the truth that can only be seen by forensics.

Can you tell us about the research you are currently involved in?

At the moment my point of focus is forensic psychiatric patients. I am indulged in studying the service offered in my country with the hope that I can import state of the art practices from the UK utilizing the cooperation agreement that I have set with them. The first part of the study is mapping the patient’s body in Egypt with special reference to the determinants of the length of their stay in the high secure wards. This requires a lot of work to establish a culture and understanding of predictors of violent behaviour. This work comes within my funded project that we have now come to call LIFE project.

Why is this work important to the field of forensic science and what do you hope to achieve by carrying out this research?

Our hope is to be able to establish guidelines to predict violent patient behaviours and thus be able to predict patients who are in need of extended stay in forensic wards. This will help in turn to reduce unnecessary length of stay of patients. By the end of this work I hope to be able to publish a white paper of effective forensic psychiatric practice as a guiding document to help in the decision making process when patients are discharged.

Do you have any words of advice for students wishing to pursue a career in your field of work?

My advice for students who want to pursue a career in forensic medicine is to specialize as early as possible. The earlier you specialize and maybe even subspecialize the quicker you grow in the field. Master your passion area and own it then try to build on it from early on. You build your name from day one in the field so build a name that goes with a specialization. It is also important to understand why you are in the field. Understand that you give bones a voice and that without you the truth will be buried indefinitely so it is important to take this calling very seriously.

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Keeping the Skies Safe with Analytical Chemistry

Ever since events such as 9/11, the Lockerbie bombing and the (fortunately) failed shoe bomber, the stringency of airport security has been ever increasing. Anyone who has passed through an airport has no doubt witnessed the occasional swabbing of luggage or electronic items. The staff will take a quick swab of the item, stick it into a mysterious machine and usually send the passenger on their way with little explanation of what has just occurred.

But what exactly are they testing for in this scenario, and just what is the instrument they’re using?

As one might expect, the biggest target of this security step is explosive substances as a counter-terrorism measure, in addition to illicit narcotics in an attempt to crack down on drug trafficking. In an airport setting, the analytical testing technique of choice is ion mobility spectrometry.

Ion mobility spectrometry (IMS) is an analytical technique used to identify chemical compounds based on the differences in the movement of ions under an electric field. The concept for the technique was established in the early twentieth century, however it was not until the 1970s that the instrumentation was actually properly developed. There are currently tens of thousands of IMS devices deployed around the world. Not only are they utilised in airports for drug and explosives screening, but also by the military for the detection of chemical warfare agents and in industrial settings to monitor air quality. The range of applications is potentially vast, but the principles of operation are the same.

As you may have witnessed, a small swab is rubbed over the surface to be tested, typically a piece of luggage or an electronic device such as a laptop, before being inserted into the ion mobility spectrometer. As the sample needs to be introduced in its gaseous form, the swab may be subjected to heating in order to thermally desorb analytes from the swab and allow them to be transported into the instrument for analysis. In order to manipulate the analytes entering the instrument, they must first be converted into ions, their charged form. Ionisation is typically achieved using a radioactive source, such as 63Ni (nickel-63) or 241Am (Americium-241), which first form reactant ion species from the carrier gas (usually air), which then leads to the ionisation of the sample material. These newly-formed ions will then enter a region under an electric field and drift towards a series of electrodes. The ions will pass through the drift region at different speeds depending on the shape and size of the ion clusters and strike the electrodes, the signals being amplified and detected. Depending on the instrument and needs of the analysis, either positive or negative ions will be produced (in some cases both simultaneously).

ims

IMS schematic. Source: Smiths Detection (www.smithsdetection.com)

The IMS utilised in airports will typically hold a database of known explosive and narcotic substances against which to compare samples. There will be a certain threshold, typically based on peak intensity, that must be reached before a positive identification will be indicated, and if there is a “match”, the operator will be alerted to a potential identification.

In comparison to other analytical tools available, ion mobility spectrometers are far from being the best. For instance mass spectrometry, an alternative technique for the analysis and identification of chemical compounds, can offer greater sensitivity, higher resolution, improved accuracy and better identification. So why use IMS? It essentially comes down to cost and ease of use. The simple design and ability to operate at atmospheric pressure means the instruments can be fairly small in size, some even being hand-held and so rendering them completely portable. They have low power consumption, so can simply be powered by a few AA batteries. The ease of use of the IMS means anyone can be trained to use the instrument, thus technical or scientific expertise is not required.

But what is perhaps most important for use in an airport setting with potentially thousands of passengers each hour, is the ability to conduct analyses quickly, and this is something that the IMS can offer. Many commercial ion mobility-based instruments can provide results in a matter of seconds. For instance, the IONSCAN by Barringer (now owned by Smiths Detection) boasts the ability to detect over 40 explosives and narcotics in just 8 seconds.

In a security setting there are three primary types of IMS that may be encountered. The smallest of the devices are handheld and sample by drawing in analytes present in the atmosphere. These may be used to analyse potential hazards relating to unattended baggage, for example. The second type, which is perhaps the most commonly encountered IMS in airports, is a benchtop instrument which requires introduction of the sample via some type of swab. And finally, some airport security units may utilise a larger, human-sized IMS portal. This setup uses airflow to dislodge particles of explosives or drugs from clothing or the passenger’s body and analyse them.

Unsurprisingly, the instruments are not infallible, and false positive or negative results are a possibility. Some ions will have the same drift time so may be indistinguishable from known explosives or drugs, triggering an alarm. In actual fact this response may simply have been caused by a cosmetic or pharmaceutical product that happens to produce a response similar to a known narcotic. On the contrary, dirt, oil and other contaminants may mask the presence of substances of interest, thus causing no alert despite the presence of a drug or explosive.

Furthermore, the IMS is somewhat limited in that it can only identify the presence of a compound contained within its database. So whereas it may be able to detect common explosives such as RDX, TNT and PETN, and frequently encountered narcotics such as cocaine, heroin and cannabis, it would not necessarily alert to the presence of an unknown compound (unless it was very similar in chemical structure to something in the database).

Fortunately research in the field of analytical chemistry is constantly ongoing, aiming to improve instrumentation and analytical techniques to resolve these issues and ultimately produce more reliable and robust security measures.

 

References

G. Ewing et al. A critical review of ion mobility spectrometry for the detection of explosive and explosive related compounds. Talanta. 54 (2001) 515-529.

Homeland Security Science & Technology. IMS-Based Trace Explosives Detectors for First Responders. [online] Available: https://www.dhs.gov/sites/default/files/publications/IMSTraceExploDetect-SUM_0506-508.pdf

Smiths Detection. Ion Mobility Spectrometry (IMS). [online] Available: https://www.smithsdetection.com/index.php?option=com_k2&view=item&layout=item&id=40&Itemid=638

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Interview with Forensic Geophysicist Dr Jamie Pringle

IMG_1916

What is your current job role and what does this involve?

I am currently a Senior Lecturer in Geosciences at Keele University in the Midlands. My time is divided between teaching undergraduate and postgraduate students, supervising MSc and PhD students, and doing research and forensic casework. I teach on a wide range of Degree Programmes, including Forensic Science, Environmental Science, Geoscience/Geology,and Geography programmes, as well as M.Geoscience undergraduate Masters and the MSc in Geoscience Research. My PhD students are, however, mostly focused on forensic geophysics projects, for example, characterisation of mass burial sites, or looking at optimum detection methods to detect clandestine graves of murder victims. These student researchers do most of the hard work! Part of our role is also to engage with the public and communicate our research to lay people, including school children, interested adults and other scientists. For example, we run a bi-annual CSI event in Stoke-on-Trent, this year focusing on a HLF-funded Science behind WW1 event.

How did you come to be involved in forensic geophysics and what initially attracted you to this field of work?

I have come from a geoscience background, and when I was studying for a PhD, I became really interested in how geophysics can help the detection of buried objects, sometimes up to 10 m below the ground! This led onto various roles to do this, and, when at Keele University, I became involved in a cold case search by North Wales Police which piqued my interest and I have been hooked on forensic geophysics ever since!

Can you tell us about the research you are currently involved in at Keele University?

Ok so a lot of unsolved murder cases include the search for clandestine graves of murder victims; without the body, it is, generally, very difficult to obtain a murder conviction of a suspect. Detection rates of victims of unsolved murders over significant periods of time, say of 1+ years, are generally poor. Therefore collaborative researchers are undertaking controlled experiments, in order to see what methods may work best to find a body which has been missing for a particular length of time, in specific soil and ground conditions. These controlled experiments use pig cadavers as human analogues, due to their similarity in body/organ sizes, tissue:fat ratios, skin/hair type, etc. These can be for significant periods of time monitoring them, for example, I have been monitoring some for 9 years of burial so far. 6 years of multi-technique geophysical survey results can be viewed here. Interestingly GPR, which everyone uses, may not be the best geophysical technique in certain soil types, electrical resistivity may be better in clay-rich soils for example. An unexpected result has been the ability for the decompositional fluids of victims to be detected, and even allow a Post-Mortem Interval to be determined, based on its conductivity.

We have also been looking at geophysical survey results from graveyard burials in different graveyards and cemeteries, in order to push back the geophysical responses of older burials and even been involved in looking for Medieval mass burials of the so-called Black Death Plague in Central London! We have, with colleagues, even been looking at indoor areas to identify forensic objects of interest and the use of drones for location purposes.

Further afield, I have also been assisting colleagues in Spain look for mass burials of victims from the 1930s Spanish Civil War and sadly more modern victims in Colombia using near-surface geophysical methods.

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Aside from research, have you had any involvement in police casework, and if so what does this typically involve?

As mentioned, in the UK this has generally been less on active search cases for the missing (which are, most commonly, solved by conventional Police investigations), and more on unsolved murders over longer periods of time (so-called cold cases). This will involve reviewing the case and any previous information/search data, then visiting potential search sites, collecting trial geophysical data and confirming the local soil types, before conducting full geophysical surveys. If there are any anomalous results in the resulting geophysical datasets, then the Police Service search teams are contacted and intrusive investigations may then commence on targeted anomalies. The North Wales paper is a good example of this. As there are less time restrictions, we can also conduct control grave studies, by burying a ‘pretend’ victim in a particular depositional environment, to see what method may work best to find them. We did this to look for one of the so-called ‘IRA Disappeared’ who was buried in a beach, so we buried a mannikin in a beach to see what would work to find ‘her’, which was successful.

Do you have any words of advice for students wishing to pursue a career in your field of work?

Many of our students (undergraduate and postgraduate) study for a more general Degree (e.g. Geoscience) which can give them generic skills that they can use in a whole host of applied employment, for example in the geotechnical site investigation world, environmental contaminated land issues and characterization, general exploration, mining, etc., so that a forensic geophysical project can still lead to employment, even if it is not in a forensic geophysical capacity. A project geophysicist role in a geophysical company will sometimes be involved in both active and cold cases, and even for the search for unmarked burials in cemeteries in graveyards, so it can be a vary varied job role, it was for me!

Is there anything else you would like to add?

If you like a varied role, are inquisitive and like problem-solving tasks, but are still observant and rigorous, then this area may well be for you! Why not get in touch?!

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Forensic Investigation Conference: Search and Identification

Conference: Forensic Investigation Conference: Search and Identification

When: 13-14th May 2017

Where: Glyndwr University Wrexham

“Wrexham Glyndwr University and UK-K9 are jointly organising the first Forensic Investigation Conference to be held at the University. The two day conference will include a number of speakers who all specialise in different aspects of Forensic Investigation with special focuses on Search or Identification. As well as covering aspects on fire, explosives and drugs investigation there will be strong focus on the use of cadaver dogs in both land and water searches. A number of case studies will be presented covering human identification, decomposition and how forensic investigation can be enhanced by future research and collaboration. Alongside the presentations there will be a student poster conference displaying current research in forensic science, and the programme will also include search demonstrations with the dogs.”

The conference will host a number of fantastic speakers, including researchers in forensic taphonomy and anthropology, search and recovery experts, detection dog trainers and more. Students are invited to take part in a poster presentation for a chance to share and discuss their research.

For further information and to sign up to the event, visit: www.wgu.ac.uk/ForensicConference