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

Interview with Forensic Archaeologist & Researcher Amy Rattenbury

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

By training I’m a Forensic Archaeologist but currently work as a lecturer at Wrexham Glyndwr University teaching on the BSc (Hons) in Forensic Science. My day to day job is teaching student groups across all three years of the programme in a range of subjects such as Crime Scene Investigation, Anatomy & Pathology and the Forensic Investigation of Mass Fatalities. As well as delivering the theory I set up a lot of the practical work that the students do such as fingerprinting workshops, organ dissections and simulated crime scenes that we mock up in our Crime Scene House. I also supervise a number of student research projects mainly in the area of Taphonomy which we conduct on our ‘Body Farm’

What initially attracted you to this field of work?

I had always been interested in science and particularly forensic science and initially took a degree in Forensic Biology at Staffordshire. I always imagined that I would go on to work in a laboratory or doing fingerprint comparisons until I took a module in ‘Identification of Human Remains’. This really sparked my interest in human osteology and made me pursue a MSc in Forensic Archaeology and Crime Scene Investigation at Bradford University where I found my very niche area in search and recovery of human remains. I started teaching anatomy alongside completing my MSc and found a real love for being in the classroom. It gives me an ideal role in being able to share what I’ve learnt so far whilst still being able to pursue my own research and industry related work. Looking back now I can’t imagine not being a teacher. There’s something about introducing students to concepts they had never considered before that really exciting. And sometimes they come back to you later on in their academic careers and actually end up teaching you something; that’s a really rewarding feeling.

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

We are really lucky here at Glyndwr to have Wales’ first and only Taphonomic Research Facility which is licensed by DEFRA. This ‘Body Farm’ allows us to conduct a number of research projects looking at decomposition which could necessarily be hosted by other universities without a dedicated, rural area in which to conduct their research. This coupled with a high calibre research lab in our Chemistry Department has really allowed both myself and students to expand research ideas. Current student projects which are out on the body farm include:

  • The effect of clandestine burial decomposition on soil chemistry and vegetation
  • How tattoo identification is effect by post mortem changes
  • A comparison of decomposition rates in fresh and stagnant water

I am also hoping to set up my own research once the temperature improves slightly and this will be looking at how oxygen deprivation (i.e. vacuum packing) affects taphonomic changes. This is a research project based on a pilot study I supervised, conducted last year by Shareei Singer at the University Centre Southend, and we hope to expand this further by looking at more samples, over a longer time frame whilst also improving the analysis methods used.

What are some of the biggest challenges in your field of work?

Teaching is a challenging role in the first place, but even more so at University level where there is an increased need to challenge students academically, and this can be particularly difficult field to get in to early in a professional career. I’m only 25 so it’s been very much a case of putting myself out there for any and every opportunity to prove myself and gain any experience I can. You really have to show not just your ability as an academic but also a drive and passion for the subject and the students. It is a highly competitive area, not only in terms of securing jobs in the first place, but then going on to conduct and publish research whilst still maintaining high quality, engaging session, for students every week. For me in particular, I find the sheer volume of books and journals I have to read, to ensure that my delivery keeps up with the speed that the area is progressing, a little daunting. But when it’s a subject that I’m passionate about, and books I would likely read anyway, it does make it easier!

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Aside from research, are you often involved in police casework or consultancy work, and what does this typically involve?

I’m not currently involved in any active police work but I did only move up to North Wales around 6 months ago. It is something that I am very keen to start and hope to build up connections in the area to so this. I do some other consultancy work in different areas of forensic search. I work quite closely with UK-K9 who are a search dog training team. They specialise in training dogs to search for a variety of forensic evidence including human remains, explosives and drugs. We are currently working to improve the use of the human remains detection dogs on water and particularly in salt water setting such as costal searches. They are also involved in a lot of cold case reviews and large scale searches which I can offer an archaeological perspective on. I have also recently taken up a consultancy position with Kenyon International Emergency Services who deal with crisis incidents world-wide. I am currently awaiting deployment but once I am called in the role could be anything from collecting evidence at aeroplane crash sites to helping with disaster victim identification during natural disaster.

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

For students wanting to go in to the forensic science generally just make sure you have it clear in your head before you start that it isn’t going to be how you see things portrayed in the media, I wouldn’t want you to be disappointed or put off once you start the course. I would say trying to get any sort of work experience is going to be crucial. Experience is essential nowadays but still almost impossible to get in crime related areas so think outside of the box a little bit. There are lots of labs you could do placements in that, although aren’t forensic can help you to learn and demonstrate key skills. I worked in a drinking water testing lab and in a haematology lab for a little while, both of which helped learn more about preventing cross contamination. But there are lots of other areas you can volunteer in such as becoming a PCSO, the Appropriate Adult services or any other charity that deals with victims of crime or offenders.

For students wanting to become educators I would say persevere. Remember what made you so passionate about that subject in the first place and share this with you students. It’s amazing how much more progress you make once you’ve learnt to foster this positive learning and collaborative environment. The planning and the marking will get easier, I promise!

 

Follow Amy on Twitter at @amy_rattenbury

Forensics at Glyndŵr can be followed on Twitter or Facebook.

Sex Determination with Raman Spectroscopy

Sex Determination with Raman Spectroscopy

The ability to quickly identify a victim or suspect during a criminal investigation is crucial, and the use of fingerprinting and DNA profiling often proves invaluable in this. However, a fingerprint or DNA profile can only be associated with an individual if there is an alternative profile or database match for comparison.

But what can investigators do when comparison profiles are not available, rendering biological fluids found at crime scenes somewhat useless?

The capability of instantly establishing alternative information relating to a suspect – such as sex, age or a phenotypic characteristic – based on the analysis of the evidence could be a substantial benefit to an investigation.

In recent years, the use of both well-established and novel analytical techniques to ascertain information relating to a suspect or victim from bodily fluids has been the focus of a great deal of research. With an increasing number of analytical instruments becoming field portable, the possibility of in situ analysis at crime scenes and instant suspect information is quickly becoming a reality.

Raman Spectroscopy and Sex Determination

Most recently, researchers at the University of Albany (Muro et al, 2016) have highlighted the possibility of using portable Raman Spectroscopy to determine the sex of an individual based only on their saliva in real-time.

The study utilised a total of 48 saliva samples from both male and female donors of multiple ethnicities, depositing the samples onto aluminium foil and drying overnight. Samples were then subjected to Raman analysis and the chemical signatures scrutinised to determine whether or not the saliva of male donors differed from that of female donors.

Raman Spectroscopy is a non-destructive analytical technique used for analyte identification based on molecular vibrations. As a basic explanation, monochromatic light is initially directed towards the sample, some of this light simply passing through the sample and some of it being scattered. A small amount of this scattered light experiences an energy shift due to interactions between the sample and the incident light. These energy shifts are detected and transformed into a visual representation. The resulting Raman spectrum typically plots frequency vs intensity of the energy shifted light. The positions of different bands on this spectrum relate to the molecular vibrations within the sample which, if interpreted correctly, can allow for the identification of analytes.

Raman spectra are somewhat characteristic of the chemical composition of the sample. In the case of the saliva analysed in this study, the features of the spectra were largely caused by amino acids and proteins. When comparing the respective spectra from male and female donors, by eye they appear remarkably similar. However using multivariate data analysis, a statistical technique used to analyse data with multiple variables, the researchers were able to distinguish between the saliva of male donors and that of female donors, reporting the ability to ascertain the sex of the donor with an accuracy of an impressive 94%.

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Comparison of male and female saliva Raman spectra (Muro et al, 2016)

Although only a proof-of-concept paper, the research demonstrates the possibility of using portable Raman spectroscopy as a method of elucidating donor information, in this case sex, through the analysis of a bodily fluid. The researchers suggest further work will be conducted to include other bodily fluids and donor characteristics.

At this point, the usefulness of the research is limited. Although instantly establishing the sex of the donor of a bodily fluid can aid investigators in developing a suspect or victim profile more efficiently, the pool of potential donors is still huge. The total of 48 saliva donors used in this study is of course not a sufficient representation of the population, thus a much larger sample set would be required to fully evaluate the technique, including non-laboratory setting experiments. Furthermore, there is a wide range of medical conditions and additional factors that can result in changes in the chemical composition of saliva and thus could influence the effectiveness of this technique. Whether or not certain diseases or external influences can hinder gender determination using this method would need to be investigated.

Previous Research

The idea of utilising analytical chemistry to ascertain donor information is not in itself novel, and other researchers have attempted to achieve the same goal through different means.

In 2015, scientists also based at the University of Albany (Huynh et al, 2015) developed a biocatalytic assay approach to the analysis of amino acids in fingerprints to determine the sex of the donor. The study boasted an accuracy of 99%, with the sex differences believed to be due to the higher concentration of amino acids in fingerprints deposited by females.

Research by Takeda et al in 2009 used Nuclear Magnetic Resonance (NMR) Spectroscopy to determine differences between the urine and saliva samples of different donors based on the detection and comparison of different metabolites. Certain compounds, including acetate, formate, glycine and pyruvate, were found in higher concentrations in male samples, allowing for the differentiation between male and female bodily fluids.

The focus of such research is not limited to sex differentiation, for instance some research has even focused on establishing whether a blood sample belongs to a smoker or non-smoker. Utilising gas chromatography mass spectrometry with a solid phase microextraction pre-concentration step, Mochalski et al (2013) were able to effectively distinguish between the blood and breath of smokers and non-smokers due to the ten-fold increase in levels of benzene and toluene, a conclusion which has been repeated by other researchers.

Looking at just this small handful of studies, it becomes evident that certain analytical techniques have the potential power to ascertain a range of information about the donor of a bodily fluid. However all of these immunoassay and mass spectrometry techniques are typically time-consuming, requiring the transportation of a sample to a laboratory, sometimes extensive sample preparation, followed by a form of analysis that will often destroy the sample. This is evidentially not ideal during a time-sensitive criminal investigation in which sample amount may be limited.

To an extent, the research utilising Raman spectroscopy to determine sex from saliva does alleviate some of these problems. The portability of Raman devices allows for in situ analysis, removing the need for expensive and time-consuming laboratory analysis. As Raman spectroscopy is based on the interaction between the sample analyte and light, it is a non-destructive technique, allowing the sample to be preserved for storage and further analyses is required.

Although these techniques do not hold the power of DNA in almost irrefutably identifying the suspect, they may at least aid investigators in narrowing down their pool of suspects and steering the investigation in the right direction. No doubt further advances in analytical chemistry will allow for more accurate and robust techniques in the future.

 

References

Huynh, C et al. Forensic identification of gender from fingerprints. Anal. Chem. 87(2015), pp11531-11536.

Mochalski, P et al. Blood and breath levels of selected volatile organic compounds in healthy volunteers. Analyst. 7(2013), pp2134-2145.

Muro, C. L et al. Sex determination based on Raman Spectroscopy of saliva traces for forensic purposes. Anal. Chem. 88(2016), pp12489-12493.

Takeda, I et al. Understanding the human salivary metabolome. NMR Biomed. 22(2009), pp577-584.

 

Interview with Postgraduate Researcher Winsome Lee

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What is the focus of your research at the University of Leicester?

My research focus, namely for my dissertation is a comparative study of the forensic science progression in Hong Kong over a 40 years time frame. Hong Kong is where I have been brought up, and forensic science in the city is always covered with the mysterious veil. In 1965, we had our first forensic case. Till today, more than 40 years have passed by, it will be essential to evaluate how much we had progress.

Other than the dissertation research, since my focus is on forensic anthropology and forensic archaeology, I am also doing different excavation field schools, projects,  and osteology related research with other institutions.

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

Technology and forensic techniques develop in a pace that we would never catch up with. However, due to constraints, not much comparative studies have been done, as an evaluation of the progress and development of the field, on the one hand. Sadly, funding is usually not entirely willing to sponsor studies of this sort, as they are hoping for new discovery most of the time, which likely lead to over generalization of ideas. Given the fact that forensics subjects heavily to experiences and contexts. Therefore, comparative study of forensic science is something that the profession needs yet tends to be overseen usually. On the other hand, a historical comparative study like the captioned one above, shows the same model over different time frames. It allows us to see the approach or policy from a macro level, namely environmental and political factors. In hope of this research, the government and the law enforcement will make improvements of their policies and models in order to facilitate the growth and application of forensic science in Hong Kong.

What does life as a postgraduate researcher entail?

Grad school life, as we all know, is tough. It is the kind of life that you have a full plate and always do not know where to start with. A lot of time management is involved, especially when I am also working alongside the study. People say you can use the senior year of undergraduate as a postgraduate tryout, I find this mostly correct! Also, other than studying, you are constantly looking for research and publication opportunities. Every time, when we are struggling, my pals and I keep asking ourselves, “why would we do this to ourselves.” But the sense of achievement is never better when you have accomplished something and survived a semester after another.

What are your plans for after you have completed your research?

After completing the existing project in the University of Leicester, I would be looking for PhD opportunities in either bioarchaeology, or biological anthropology.

Also, I have several real life forensic projects with police and other authorities ongoing and lined up. I am all excited and looking forward to all these amazing opportunities ahead!

Do you have any advice for students hoping to pursue a position in forensic research?

Keep your mind open!

First of all, forensic science itself is a relatively broad profession. Some of my friends switched from one discipline to another after trying out things, from forensic anthropology to law, from forensic pathology to forensic photography. You never know until you have tried. So first thing will be, to grasp as many opportunities as you can, then decide.

Once you made your choice, you also have to remember that forensic scientist is a relatively narrow yet competitive profession. What I mean is that, there is only certain demand in the authorities or law enforcement for forensic experts. If no one retires, you probably will not get a job. So it is always beneficial to have a broader, or second profession focus besides forensics.

Also, it is also very important to know that not every forensic scientist is good with doing research. Some are good with applying what we have learned, rather than doing research and making new discoveries. Be open minded, and do not get frustrated! Keep in mind that, either way we are making remarkable contribution.

Follow Winsome’s blog “Traces in Bones” here.

Interview with Forensic Accountant Sundaraparipurnan Narayanan

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

I handle the forensic service line for SKP Business Consulting LLP, in India. I advise clients/corporates on fraud management/prevention strategy in the nature of setting up an in-house fraud control unit or support with operational fraud matrices in the nature of fraud analytics or fraud risk assessments, and assist in ethics or compliance investigations. With the increase in fraud, corporates are increasingly setting up in-house fraud control units to manage the risk of frauds. This includes defining the roles & responsibilities of the unit, exhibiting independence, developing a robust concern handling process and measuring effectiveness of the operations at appropriate intervals. Operational fraud management includes supporting corporates with fraud risk assessments and specific dashboards on fraud control. Supporting ethics and compliance investigations is primarily focussed towards gathering evidence from digital and documentary sources and conducting interviews of identified individuals (employees and third parties) with reference to the issue in question.

What kind of education/training do you need to work in this area?

You need to have an eye for details and you need to develop the capability of noticing inconsistencies and identifying patterns. These are enablers in this field. At the base, for the given nature of job, one should have a strong background in accounting and internal controls. Certified Fraud Examiner is a certification offered by ACFE, a non-profit working towards enhancing education relating to fraud. This certification helps resources to understand the essentials better.

How did you end up working in forensic accounting?

I was influenced by the way my mentor (Mr. Shanmuga Sundaram) worked on internal audit/internal control reviews, where he was able to spot complex frauds based on his unorthodox approach. Over time I realized that I had an interest in fraud investigations and wanted to explore that as a career. I joined Ernst & Young in their fraud investigation service line to learn and over a period the work experience supported by subsidiary reading has helped me in this field.

What are some of the most challenging aspects of this kind of work?

Gathering evidence is always challenging. In one of the reviews that I led, the issue in question was on the fraudulent manipulation of IT application data at the backend. The review involved gathering of specific traces of evidence from the logs and identifying inconsistencies. It also required exploring newer tools/techniques including wireshark attack or specific backup protocols to ensure that evidence was secured for subsequent analysis. These measures helped in concluding the investigation.

Similarly in another review, the instance of fraudulent conduct was identified in Japan. Investigation in Japan with known language constraints was challenging. We had to conduct interviews of the suspects with translators around.

How do you think this field of work could be improved?

Currently the technology is maturing in this field with digital forensics and analytics becoming more prominent than before. I believe that technological influence can change the playing field for the service in the decade to come. A move from service to solutions on fraud management also will be a game changer in the years to come.

Finally, do you have any advice for those seeking a career in forensic accounting?

My 3 points of suggestions to people joining forensic accounting are:

  1. Remember you are not a super human. You can gather only those evidences that are available, extractable and representable at the court of law. Hence be clear with the evidence that you can gather.
  2. Spend time learning. Learning gives a broader perspective of gathering evidence.
  3. Embrace technology. It will help you, add value to the field of work over time and bring in a change.

If you’re a forensic scientist (academic or industry) or a crime scene investigator and would like to be part of this series of interviews, get in touch by emailing locardslabblog[at]gmail.com.

This is Part 6 of our series of interviews with forensic professionals.

Interview Series Part 1 – Interview with Forensic Identification Scientist Alexandre Beaudoin

Interview Series Part 2 – Interview with Forensic Expert Robert Green OBE

Interview Series Part 3 – Interview with Forensic Expert & Consultant Gareth Bryon

Interview Series Part 4 – Interview with Forensic Identification Specialist Donna Brandelli

Interview Series Part 5 – Interview with Forensic Video Analyst David Spreadborough