Hilary J.
Hamnett†
*,
Amanda E.
McKie
and
Calum
Morrison
Forensic Medicine & Science, School of Medicine, Dentistry & Nursing, University of Glasgow, University Place, Glasgow, G12 8QQ, UK
First published on 10th July 2018
The ability to work in a group is an important skill for graduates. Although the experiences of undergraduate students with group work have been extensively explored, there is much less information in the literature regarding postgraduate students and no information on those enrolled in science programmes. In this study, participants from a taught applied chemistry postgraduate MSc programme report their attitudes and experiences with group work. The usefulness of this approach and of scientific discourse for learning and teaching several key concepts is also explored. Participants in the study completed attitudinal questionnaires and group/individual multiple choice question (MCQ) tests. They reported a range of skills developed through working together, mixed preferences for group vs. individual assignments, and comparison of the mean MCQ test scores between participants working individually and in groups demonstrated no statistically significant differences.
In addition to the employability benefits of group work, there is strong support for having students learning in groups. Comprehensive research reviews and studies have verified that learning in groups has several advantages over traditional lessons (Chiriac and Granström, 2012). Firstly, by working together, students can undertake more difficult and substantial projects than they might have undertaken on their own (Cooper, 1995; Nordberg, 2008). Secondly, the process of working in a group to solve problems can help students develop more ideas and solutions (Johnson et al., 2007; Gillies and Boyle, 2010; Marks and O’Connor, 2013), and thirdly, some students are more motivated, retain information for longer, and are more actively involved in their learning (Johnson et al., 2007; Gillies and Boyle, 2010; Marks and O’Connor, 2013).
There are principally two approaches that students use in group work situations, namely cooperative learning and collaborative learning. Cooperative learning occurs when students sit together in a group, but work individually on separate parts of a group task e.g., sections of a Microsoft PowerPoint presentation. At the end of the assignment, they merge or paste (Hmelo-Silver et al., 2008) the parts together to form a joint product (Marks and O’Connor, 2013). This can be a useful approach to making a large and complex task manageable. However, individual students can too easily focus only on their own specific task, not really understanding the other components or how they contribute to the project as a whole (Gillies and Boyle, 2010).
In collaborative learning, all group members work together on a common task to produce a joint outcome (Chapman and van Auken, 2001). This involves students listening to, debating (Lou et al., 1996) and building on each other's ideas (Gillies and Boyle, 2010), and is the type of group work specifically mentioned in our institution's graduate attributes (University of Glasgow, 2017). The collaborative approach also appears to provide greater freedom [from instructors] of operation for its members and, in return, is likely to yield more innovative results (Strauss and Alice, 2007). There is empirical and theoretical research that overwhelmingly supports the active engagement and development of higher-order cognitive skills associated with collaborative group work (Lou et al., 1996; Johnson et al., 2007; Hillyard et al., 2010).
There are a surprisingly small number of studies in the literature dealing with group work by postgraduate students, and, to the authors’ knowledge, none reporting the experiences and attitudes of science students. Postgraduate taught students are an important resource for education research as their numbers are increasing (Barradell and Peseta, 2017). They are also an articulate and critical group (Barradell and Peseta, 2017) and the characteristics of Masters students, their courses, the contexts in which they operate, and the desired learning outcomes mean that thinking about teaching–learning processes at Masters level should not simply be led by research into undergraduates (Kroll, 1985). Postgraduate cohorts are diverse, with high percentages of international students, mature students, and those with experience in the workplace. For those students embarking on postgraduate study directly from undergraduate degree programmes, it is important to understand their attitudes when embarking on a higher degree, as negativities from previous experiences can be carried into future groups, no doubt affecting that group's climate (Strauss and Alice, 2007; Hillyard et al., 2010).
In the existing studies involving postgraduate arts students, the diversity of postgraduate cohorts has been a source of both frustration and enhanced learning and teaching. In one study, those with better English-language skills felt peer pressure to do the bulk of the written work (Nordberg, 2008), but in another, the students described group work as “inspiring each other and opening up thinking” (Bowering et al., 2007). In a study involving postgraduate students enrolled on a Construction Management course, with varied nationalities and professional backgrounds, the diversity provided an excellent opportunity for students to share knowledge and to generate different ideas for group assignments (Zou and Darvish, 2006). Dealing with diversity in group work can also be a challenge however, as students are required to assess, process and react to unfamiliar values, cultural norms and ideas (Woods et al., 2010). Science postgraduate students are of particular interest for the topic of group work as most chemists and other scientists spend their professional careers working in groups (Kroll, 1985), since the team approach to problem solving is the norm in many industrial settings (Cooper, 1995).
The aim of this study was to report experiences and attitudes of postgraduate taught science students around group work, and highlight any potential differences from those of undergraduate students. In addition, we aimed to explore scientific discourse among postgraduate students (Repice et al., 2016) by giving them the opportunity to discuss key science concepts in small groups.
In the first part of the study, during July–September 2015, 20 postgraduate taught students from academic years 2014–2015 and 2015–2016 were asked about their experiences with group work using a single-question questionnaire requiring a free-text response. In the information sheet for this preliminary study, participants were told that the purpose of the study was to determine postgraduate science students’ experiences with group work. In the questionnaire, the instruction given was: “When you take part in a group exercise, describe what the experience is like for you.” All students were given a participant information sheet and signed a consent form. Ethical approval for this preliminary study was granted by the University of Glasgow Medical, Veterinary & Life Sciences Ethics Committee (project no. 200150002). The results of this study were used to guide the contents of a more detailed questionnaire.
In the second part, carried out during Autumn 2016 and 2017, nine MSc students from the academic year 2016–2017 and seven students from the academic year 2017–2018 (100% of each cohort) completed a questionnaire on their experiences with and attitudes to group work (see Appendix 3).
In the third part, the 2016–2017 and 2017–2018 cohorts also participated in three formative assignments on key concepts from the curriculum during September–December 2016 and 2017. Key concepts are those considered to be the basic building blocks of knowledge, and differ from threshold concepts, which represent crucial points in conceptual understanding, without which students will encounter great difficulty in moving forward (Barradell and Peseta, 2017). During the three key concept assignments, students either worked individually or discussed the concepts in randomly assigned groups of three. Random numbers were assigned to each student using the RAND() function in Microsoft Excel. The numbers were then sorted into ascending order and groups were filled by starting with the first student in the list. The remaining students worked individually. All students were given a participant information sheet and signed a consent form. Ethical approval was granted as before (project no. 200160004 and 200170003).
All data was collected in paper format then transferred to Microsoft Excel for thematic analysis. Feedback from the students on their individual or group work experience was captured using a combination of written and audio methods after the completion of each assignment.
Participants were given the aims of each assignment (Table 1) and directed towards the advance assignment resources a week before each MCQ test. The three assignments were spaced throughout a 10-week semester. Introductory lectures associated with the content were given throughout the semester, were general in nature and not designed to cover all of the material in the MCQs or act as a replacement for the advance assignments. The advance assignment was similar each time (e.g., short videos, Microsoft PowerPoint slides, book chapters, etc.) and was posted on a virtual learning environment (VLE). Participants were told on the day of the test if they would be working in groups or individually.
Post-mortem redistribution | Immunoassay | Alcohol calculations |
---|---|---|
Aims of the assignment | ||
• Explain the mechanisms behind PMR | • Explain the general principles behind immunoassay | • Explain the assumptions behind alcohol calculations and determine when they are appropriate |
• Describe PMR to a lay audience | • Recognise the appropriate use of immunoassay in forensic toxicology | • Explain the pharmacology that makes alcohol calculations possible |
• Differentiate PMR from other post-mortem phenomena (e.g., bacterial production of alcohol) | • Differentiate between types of immunoassay (e.g., direct vs. indirect) | • Identify common errors in alcohol calculations |
Advance assignment | ||
• Watch the Chemistry of Death video (American Chemical Society, 2014) | • Watch a video on the immunoassay process (Microbiotic, 2015) | • Watch the Chemistry of Alcohol and Hangovers video (BytesizeScience, 2013) |
• Read a book chapter by an expert in the field (Drummer, 2008) | • Read two book chapters from forensic toxicology textbooks (Hand and Baldwin, 2013; Smith, 2015) | • Read a book chapter from a forensic toxicology textbook (Scott-Ham, 2016) |
• Review the Microsoft PowerPoint slides from a webinar (Zarwell, 2014) | • Read a set of professional body guidelines (UKIAFT, 2014) |
The students were given up to 50 minutes to complete the MCQs. Randomly assigned groups of students (two groups of three participants in 2016–2017 and one group of four in 2017–2018) and those working individually were based in different rooms. All students worked in a group at least once during the study, with some always working in a group, due to the random nature of the allocations. The students undertaking individual MCQs were under examination conditions i.e., no talking. Neither set of students had access to their mobile phones, notes, computers or the VLE, although the questions were specifically designed such that the answers would not be available on the internet or in a textbook (Parmelee et al., 2012). The students working in groups were required to come to a consensus on the best answer to each question. Roles such as ‘manager’ or ‘record keeper’ were not assigned to students working in groups by the researchers in this study (Heller and Hollabaugh, 1992). Both sets of students were invigilated by a researcher. Following completion of the MCQs, feedback was obtained from the students, before they were brought back together in the same room. During the feedback collection students were asked questions on their perceived difficulty of the MCQs, the length and usefulness of the advance assignments, their preference for group or individual work and their views on the timing of the introductory lectures (before or after the MCQs). The discussion was either noted down in writing or audio recorded. Themes from the recording were noted by researchers after a general listening review. Feedback was collected without any participants’ names being ascribed to comments. The answers to the MCQs (correct or incorrect) were given orally to all of the students together by one of the researchers (papers were peer marked out of 10) and students made a note of their mark and any questions they had answered incorrectly. Question papers were handed in and answer sheets circulated with the correct answers and explanations. Further clarification was provided by one of the researchers.
We selected the three key concept sessions because each one dealt with very different conceptual material, but all involved activities commonly faced in the forensic toxicology workplace (Repice et al., 2016). The three key concepts chosen were post-mortem redistribution, immunoassay and alcohol calculations. The teaching materials for each concept are given in Appendix 1.
Post-mortem redistribution (PMR) describes how the movement of drugs around the body after a person has died can lead to post-mortem drug concentrations that do not reflect ante-mortem concentrations (Drummer, 2008). Some drugs are more susceptible to this effect than others, and the occurrence of PMR depends on a number of factors (Pélissier-Alicot et al., 2003). PMR is easily confused with other post-mortem phenomena, and is important for the correct interpretation of post-mortem forensic toxicology data.
Immunoassay is a technique that is used in forensic toxicology to rapidly screen for the presence of groups or ‘families’ of drugs e.g., opiates, in biological fluids. Immunoassay results are presumptive, that is, any findings must be confirmed by another, more sophisticated technique such as gas chromatography before the result can be used in a court of law. It is important that students understand the principles of the different types of this technique in order to correctly interpret immunoassay test data, and determine case strategy.
Alcohol calculations, sometimes called Alcohol Technical Defence calculations, are used in forensic toxicology to predict alcohol levels within a person's body before, during or after a particular incident, using a number of facts. The calculations involve quantitative skills, including solving equations and working with numerical values to obtain a quantitative answer (Repice et al., 2016). A calculation is not always appropriate, depending on the circumstances of the case, as a number of assumptions must be made, therefore it is important that the students understand not only how to carry out the calculations, but when they are appropriate, what the common pitfalls are, and the pharmacological properties of alcohol that make the calculations possible.
However, one of the most common themes was differences between group members and participants often commented on how useful the different perspectives of their fellow students were during group assignments. This sample of the student ‘voice’ (Gillies and Boyle, 2010) was used to inform the questions in the main questionnaire; the themes of meeting other students, increased confidence, fairness of grading, and diversity in group work were drawn from the responses and combined with questions from the literature (Bartle et al., 2011; Marks and O’Connor, 2013) to be explored further.
It can be seen that overall the responses were mixed, with a small number of outliers evident. Specifically: an increase in confidence associated with group work; that group assignments were a good way to get to know other students; the participants’ preference for group work over individual assignments; that group work gave participants a chance to experience diverse views and opinions; and a preference for smaller group sizes.
In the free text area for Q4, the participants listed a number of drawbacks to group assignments:
Commitment: whether that is people putting in the effort in their own time at home, or making the effort to attend group meetings to discuss findings
Disagreement over some points or opinions
If the people you are working with attend different classes, it can be hard to arrange meetings
If the assessment is summative and you get a group mark it can be frustrating/unfair when team members don't pull their weight. You lose control of your own grade.
In the free text area for Q5, the participants gave a wide range of skills developed from group assignments. The most common were organisational, critical thinking, mediation, communication, teamwork and active listening skills. However, the influence of diversity was also clear in the responses:
The ability to consider everyone's point of view/learn different ways of thinking/be open to new ideas/learn how to approach a topic in a new (sometimes better) way
How to let go when other people don't agree with you
Recognise when to ask for help
The ability to give your ideas and opinions in an effective and easy way to understand/explain myself better
Confidence: I need to be confident in the work I bring back to the group
The ability to develop an understanding of various techniques of learning/studying and incorporating them into your own work
The mean scores (out of 10) for the individual MCQ tests were 6.8 (immunoassay), 5.7 (PMR) and 4.6 (alcohol). For the group MCQ tests, the corresponding mean scores were 6.4, 6.0 and 5.1, respectively. The differences between the mean scores for individuals vs. groups were not statistically significant for any of the MCQ tests (p = 0.5–0.7), as determined by two-tailed, two-sample equal-variance t-tests carried out in Microsoft Excel.
After the MCQ tests there was some additional discussion and feedback given orally as the MCQ papers were marked. Some participants fed back that the MCQs were difficult, but a useful tool for checking their understanding of the key concepts, particularly as it was often tricky to choose the best answer, hence requiring a deeper knowledge. Based on this feedback, this type of assignment could also be used as a revision tool.
The advance assignments were considered to be acceptable in length, taking about two hours to complete. Feedback from the students on the alcohol calculations advance assignment was that it did not prepare them well for the MCQs, and that some of the set reading was confusing and difficult to follow. For the immunoassay advance assignment, some participants had read a number of different, additional sources (“supplemented their reading with googling”) and found these different resources to be confusing and conflicting.
In terms of the timing of lectures (before or after the MCQs), the results were mixed: some participants liked having the alcohol lecture first as it addressed points in the reading, meaning some concepts were clearer afterwards. Others would have preferred to have the lecture after the test to clarify the MCQ answers. Students who undertook the immunoassay MCQ test as a group reported that having a lecture on the principles of the immunoassays after the test made no difference to them in terms of the amount of preparation they undertook.
From the feedback, there was an overall positive attitude to group work for the MCQs among the participants:
Group work is more fun
In terms of learning stuff, because I did not know anything about immunoassay, learning something totally new, the discussion is very important…today's group testing was the best option for me
It was good to be in group in a sense that you were able to dissect questions, in some of the ones we noticed the wording we were like oh right OK, so we changed answers accordingly
This is perhaps not surprising, as most of the MCQs were of the single best-answer (SBA) type, and specifically designed to be ambiguous (see the discussion) and hence encourage scientific discourse.
However, the same student went onto state that
I don’t know if this is me just being antisocial, but I preferred the individual [MCQ test] last week, I felt that if I got something wrong I am responsible for it.
indicating a sense of responsibility to their fellow group members. Similarly, a student who undertook the PMR MCQ test individually commented:
When it's my own test and I do it myself and it's the wrong answer, it's my responsibility
Some of the comments received in the feedback revealed that working in a group had a restraining effect on individual participants:
I prefer to work alone, in group work there is too much deliberation and I don’t want to compromise
On my own I can go with my gut feeling
I might hold people back in a group sometimes…I have my way of doing things
The results of Q2 of the questionnaire indicate that cooperative learning is generally more common as a strategy among this set of participants than collaboration, when working on group assignments. Although there are no previous studies addressing the issue of collaboration vs. cooperation among postgraduate students, this strategy is particularly known to occur when the group assignment involves producing a lengthy document, as students feel pressure to get started on the writing and therefore limit their discussion time (Michaelsen, 1998).
It can be seen from Fig. 2 that in the responses to Q3 of the questionnaire, 88% (n = 14) of the participants chose a score of 4 or 5, agreeing that group work assignments were a good way to get to know other students. This is consistent with previous research indicating the important social consequences of group work. Group work can help students establish and maintain friendships with peers (Chapman and van Auken, 2001; Woods et al., 2010) and lead to greater social support as students get to know each other on a personal as well as a professional level (Johnson et al., 2007) and help each other in an non-threatening manner (Cooper, 1995). This extension of ties beyond the group work exercise was also reported by Bowering et al. (2007). Successful group efforts can provide the opportunity to share and solve personal problems, which increases an individual's resilience and ability to cope with adversity and stress (Johnson and Johnson, 1999). This is particularly pertinent for postgraduate students, many of whom are international students who are living away from their usual support networks, and suggests that this pedagogy is also a value opportunity for them to get to know their classmates.
Similarly, 56% (n = 9) assigned a score of 4 or 5, indicating that group work assignments increased their confidence, and this was also noted in Q5 in the skills students developed through group work. Successful undergraduate group efforts have been shown to increase self-confidence, independence and autonomy (Johnson and Johnson, 1999), and for postgraduate cohorts, where some students lack confidence with language skills, this is again particularly relevant.
Most of the participants were either neutral (score of 3) or expressed a preference (score of 4) for group assignments over individual assignments, with two participants strongly disagreeing with this statement. This is consistent with the undergraduate literature where there is no real consensus on whether students prefer to work in groups.
Eighty-eight percent (n = 14) of the participants reported scores of 4 or 5, agreeing that group work gave them a chance to experience a variety of views and opinions. In this study, because of the nature of the cohort, the groups combined students with different undergraduate degree backgrounds, cultures, native languages and areas of expertise. It has been previously reported that diversity enhances creativity by encouraging the search for novel information and perspectives, leading to better decision-making and problem solving (Phillips, 2014). By promoting a variety of ideas and opinions in groups, the individual student's experience of the task can be expanded and enlarged, and the task can be viewed from different perspectives (Michaelsen, 1998; Brandler and Roman, 2016). This was also reflected in the feedback from the MCQ tests and the answers to Q5 of the questionnaire. Again, this result is important for postgraduate cohorts, which are often diverse in nature.
Finally, a similar pattern was observed in the participants’ preference for smaller groups (88%, n = 14, expressing a score of 4 or 5). This is a common finding in group work studies. In the study by Marks and O'Connor (2013), students preferred smaller groups (2–3 members) to larger groups (4 or more members). This was mirrored in the study by Zou and Darvish (2006) where more than half of the students considered three as the most suitable group size. It has been noted that the degree of social loafing or free-riding within groups can become more pronounced as the size of the group increases (Falchikov and Goldfinch, 2000).
In Q5 of the questionnaire, the participants commented that group work helped them develop their skills of explanation. We know that through group interaction, students learn to communicate effectively (Johnson and Johnson, 1999) and use language to explain new experiences, and demonstrate a more sophisticated level of discourse (Gillies and Boyle, 2010). Through the practice of explaining scientific concepts to each other, students learn to develop skills to monitor and reflect on their own learning (Repice et al., 2016). For this particular MSc programme, the ability to explain concepts is a key skill required for future expert witness work.
In the feedback from the key concept assignments, the students commented that the questions were difficult. Most of the MCQs were of the SBA type, constructed in scenario form with an introductory stem and a lead-in question, followed by a list of four possible responses. In some cases, the four options consisted of three ‘distractors’ and one correct answer (Campbell, 2011). Distractors were based on common incorrect answers and areas of confusion that had been identified by the researchers when teaching these concepts previously. In other cases, MCQs were of the multiple true/false type, and an ‘all of the above’ option was the correct answer. A small number of the MCQs focused on definitions. The researchers avoided negatives such as “which of the following is FALSE?” when writing the MCQs.
Finding the appropriate level of difficulty for group assignments is fundamental to encouraging interaction between group members. If assignments are too easy, one member will simply act on behalf of the group. In contrast, assignments that require students to use course concepts to make difficult choices, always produce high levels of both interaction and learning (Michaelsen, 1998). Particularly at postgraduate level, it is also important that students move away from memorization and recall of facts towards solving messy, real-life, ambiguous problems (Spence, 2001). We found that these MCQs were a useful introduction for our students to the level of difficulty and the skills required for postgraduate study.
In the feedback, one student commented that group work is more fun than individual work. This is consistent with the previous finding in the literature that students find group projects more interesting than traditional methods of teaching (Dochy et al., 1999).
There are a number of limitations to this study. Firstly, the sample size is small and all participants came from a specialised MSc course at a single institution. However, the participants represent a range of countries of origin (UK, EU and outside EU), undergraduate degree subjects (e.g., chemistry or pharmacology) and cultures. Secondly, some of the students had already been introduced to these key concepts prior to this study. Thirdly, lack of completion of the advance assignments may have affected their scores and attitude to the MCQs. Fourthly, although the feedback on the timing of associated lectures was mixed, the timing may have affected participants’ feedback on the MCQs. Finally, as mentioned in Section 2, the MCQ assignments were formative. This was for both ethical and administrative reasons; as the assignments were new (therefore not part of the validation documents for the courses) and, in one instance set before an introductory lecture on the same topic, summative assessment would be inappropriate. Our decision to set formative assignments, meaning no student's final course grade depended on their group, may explain the more positive approach to group work reported for the key concept assignments, than was reflected in the questionnaire data. Our use of randomly selected groups has also not taken into account the effects of group membership on attitudes and experiences.
Future work could include summative assessment of the MCQ tests and/or the inclusion of additional aspects of Team-Based Learning e.g., the use of an individual MCQ test prior to the group MCQ test. Further research into group work attitudes and experiences of postgraduate students could include larger sample sizes, assignment of roles, instruction on effective group work, and the exploration of group composition variables such as academic performance, age, gender and country of origin.
(a) Alcohol calculations
1. Why are forensic toxicologists able to conduct alcohol calculations?
A. Previous research has shown they are usually accurate.
B. They are allowed under the Road Traffic Act 1988.
C. Alcohol exhibits linear metabolism throughout a certain range.
D. All of the above.
2. Which four pieces of information are required before an alcohol back-calculation can be attempted?
A. Time of sample collection, blood or breath alcohol concentration measured, time of alleged incident, and time alcohol was last consumed.
B. Time food was last consumed, time of alleged incident, time of sample collection, and blood or breath alcohol concentration measured.
C. Time of sample testing, blood or breath alcohol concentration measured, time of alleged incident, and time alcohol was last consumed.
D. Time of alleged incident, time of sample collection, blood or breath alcohol concentration measured, and exact amount of alcohol consumed.
3. UKIAFT recommend three rates of metabolism for alcohol calculations. They are 9, 19 and 29 mg/100 mL h −1 in blood. Why might a driver have an elimination rate of 9 mg/100 mL h −1 ?
A. They are taking the prescription medication Antabuse® (disulfiram).
B. Their liver function is impaired by disease.
C. They are dependent on alcohol (an alcoholic).
D. They are over the age of 65.
4. A driver was found in a stationary vehicle at midnight, breathalysed and found to be over the alcohol limit for driving. The driver claims he had no intention of driving until 0800 hours and you have been asked to calculate his alcohol concentration at that time. Which assumptions must you make when performing this calculation?
A. The driver has a rate of alcohol metabolism that is within the normal range, the driver did not consume any more alcohol after the breathalyser test, and the driver was not intending to drive before 0800 hours.
B. The driver did not consume any more alcohol after the breathalyser test, the driver has a rate of alcohol metabolism that is within the normal range, and the driver was in the elimination phase at the time of the test.
C. The driver has a rate of metabolism that is within the normal range, the driver did not consume any more alcohol after the breathalyser test, and the breathalyser device was working properly.
D. The driver did not consume any alcohol after the breathalyser test, the driver has a rate of alcohol metabolism that is within the normal range, and the driver was in the absorption phase at the time of the test.
5. A driver crashed his large goods vehicle at 2100 hours, and following analysis by the hospital laboratory of a sample taken at 0000 hours, his serum alcohol concentration was 60 mg/100 mL. His employer has requested a back-calculation to the time of the crash. What was his blood alcohol concentration most likely to be at the time of the crash?
A. 117 mg/100 mL
B. 99 mg/100 mL
C. A back-calculation is not appropriate in this case (you must state a reason).
D. 74 mg/100 mL
6. A woman was allegedly assaulted 2 hours after leaving a nightclub. She provided blood and urine samples 10 hours after leaving the nightclub. The concentrations were 15 mg/100 mL (blood) and 86 mg/100 mL (urine). What was her blood alcohol concentration most likely to be at the time of the alleged incident?
A. 167 mg/100 mL
B. 247 mg/100 mL
C. 205 mg/100 mL
D. A back-calculation is not appropriate in this case (you must state a reason).
7. A driver is breathalysed 2 hours after a crash and the reading is 160 μg/100 mL breath. What was his blood alcohol concentration most likely to be at the time of the crash?
A. 198 mg/100 mL
B. A back-calculation is not appropriate in this case (you must state a reason).
C. 108 mg/100 mL
D. 406 mg/100 mL
8. A driver is breathalysed following a crash and found to be over the limit. He claims to have consumed alcohol earlier in the day and after the crash, but before the breathalyser test (the ‘hipflask defence’). What information is required before an alcohol calculation can be attempted?
A. The driver's height and weight, the exact quantity of alcohol consumed (volume and %ABV) before and after the crash, the time of the crash, and the time of the breathalyser test.
B. The exact quantity of alcohol consumed (volume and %ABV) before and after the crash (volume and %ABV), the time of the crash, and the time of the breathalyser test.
C. The driver's height and weight on the date of the crash, the exact quantity of alcohol consumed (volume and %ABV) before and after the crash, the time of the crash, and the time of the breathalyser test.
D. The driver's height and weight on the date of the crash, the exact quantity of alcohol consumed (volume and %ABV) after the crash, the time of the crash, and the time of the breathalyser test.
9. A driver crashed his car at 0700 hours, and following a blood test at 0830 hours, his blood alcohol concentration was 44 mg/100 mL. As this is below the legal limit he was not prosecuted by the police, but his insurance company has requested a back-calculation to the time of the crash. What was his blood alcohol concentration most likely to be at the time of the crash?
A. 15.5 mg/100 mL
B. 72.5 mg/100 mL
C. A back-calculation is not appropriate in this case (you must state a reason).
D. 73 mg/100 mL
10. In a homicide case, death occurred one hour after the deceased was stabbed. The post-mortem blood and urine alcohol concentrations for the deceased are 30 mg/100 mL (blood) and 5 mg/100 mL (urine). What was the deceased's blood alcohol concentration most likely to be at the time of the stabbing?
A. 49 mg/100 mL
B. A back-calculation is not appropriate in this case (you must state a reason).
C. 24 mg/100 mL
D. 11 mg/100 mL
(b) Post-mortem redistribution
1. What is the mechanism responsible for post-mortem redistribution?
A. Diffusion of drug from the site of injection.
B. Diffusion across a concentration gradient.
C. Contamination from the GI tract.
D. Movement of the body after death.
2. Post-mortem redistribution can result in movement of drugs into blood from solid organs, such as the lungs, stomach and liver. Following a suspected heroin overdose, the morphine concentration in heart blood was 0.2 mg L −1 and in femoral blood it was 0.02 mg L −1 . What is the most likely explanation for these findings?
A. Post-mortem redistribution from the lungs following aspiration of vomit.
B. Post-mortem redistribution from the stomach.
C. Post-mortem redistribution from body fat.
D. Post-mortem redistribution from an injection site.
3. A deceased is found hanging and resuscitation is attempted. They were known to take fluoxetine. The concentration of fluoxetine in post-mortem femoral blood is 2 mg L −1 (therapeutic concentrations are 0.05–0.5 mg L −1 ). What is the most likely explanation for this finding?
A. The deceased took an overdose of fluoxetine before the hanging.
B. Post-mortem redistribution.
C. Pooling of blood in the lower half of the body.
D. Post-mortem bacterial production.
4. Post-mortem redistribution causes drug movements within the body after death. Which of the following is the major factor influencing post-mortem redistribution?
A. Volume of distribution (Vd).
B. Drug lipophilicity.
C. Ionisation characteristics and pKa.
D. Size of molecule.
5. Following a sudden death, two heart blood samples are taken at autopsy: sample 1 is preserved and sample 2 is unpreserved. Both are analysed and the only finding is paracetamol at a concentration of 60 mg L −1 in both samples (therapeutic concentrations are <20 mg L −1 , fatal concentrations are >100 mg L −1 ). What is the most likely explanation for these results?
A. Overdose of paracetamol.
B. Post-mortem redistribution.
C. Normal therapeutic use of paracetamol.
D. Conversion of the metabolite (paracetamol-glucuronide) back to the parent.
6. In a case of fatal excited delirium, a high level of benzoylecgonine (cocaine metabolite) is measured. No cocaine is detected. What is the most likely explanation for these findings?
A. Acute use of cocaine, which was all metabolised prior to death.
B. Post-mortem redistribution of benzoylecgonine.
C. Post-mortem hydrolysis of cocaine into benzoylecgonine.
D. Chronic use of cocaine resulting in a high background concentration of benzoylecgonine.
7. Following a suspected overdose, a hospital admission ante-mortem serum sample (in a gel tube) and a post-mortem heart blood sample are taken from the same deceased. There was a delay of several hours between admission and death. The amitriptyline concentration in the serum sample is 2 mg L −1 , and in the post-mortem blood sample it is 12 mg L −1 . What is the most likely explanation for these findings?
A. The high level of amitriptyline in the blood is due to post-mortem redistribution.
B. The low level of amitriptyline in the serum is due to drug absorption by the gel tube.
C. The deceased had not absorbed all of the amitriptyline at the point of admission, the level therefore increased before death.
D. All of the above mechanisms may have contributed to these findings.
8. Low levels (<30 mg/100 mL) of alcohol can be measured post-mortem in the blood, but not the urine. What is the main mechanism for this effect?
A. Leakage of consumed alcohol from the GI tract into the blood.
B. Post-mortem redistribution.
C. Post-mortem bacterial production of alcohol.
D. Leakage of consumed alcohol from the bladder into the blood.
9. In a suspected drug-related death, a hospital admission plasma sample and a post-mortem femoral blood sample are taken from the same deceased. Death occurred quickly following admission. The methadone concentration in the plasma sample is 1.1 mg L −1 and in the post-mortem sample it is 0.8 mg L −1 . What is the most likely explanation for these findings?
A. The low blood concentration of methadone is due to post-mortem redistribution.
B. The high plasma concentration of methadone is due to plasma protein binding.
C. Methadone is unstable post-mortem.
D. Methadone has been metabolised between admission and death.
10. In a homicide by stabbing the venlafaxine concentration post-mortem femoral blood is 0.44 mg L −1 and in heart blood it is 40 mg L −1 . Both samples were preserved. What is the most likely explanation for these findings?
A. Conversion of O-desmethylvenlafaxine (Pristiq®) into venlafaxine post-mortem.
B. Overdose of venlafaxine prior to stabbing.
C. Leakage of venlafaxine from the stomach into the heart blood.
D. Post-mortem redistribution.
(c) Immunoassay
1. Which is the best definition of immunoassay?
A. A test that uses antibodies to identify and measure amounts of a chemical substance.
B. A commonly used technique for the determination of known analytes.
C. A test where antibodies and antigens are brought together.
D. A test in which the detection of a substance depends on the reaction between an antigen and an antibody.
2. In an immunoassay, antibody binding to an antigen is based on:
A. The molecular weight of the antigen.
B. The molecular composition and spatial orientation of the antigen.
C. The presence of an isotope-labelled element in the antigen.
D. The attachment of a protein molecule to the antigen.
3. Immunoassays may be described as ‘competitive’ or ‘non-competitive’. The technique used by Forensic Medicine & Science is a competitive immunoassay kit made by Immunalysis®. In a competitive immunoassay:
A. The amount of antigen is directly proportional to the signal from the assay.
B. Antigen in the sample competes with labelled antigen for a limited number of antibody binding sites.
C. Two different antibodies compete to bind on the same site of the antigen.
D. Antigen competes with a blocking agent to bind to the bottom of the microtiter plate well.
4. A ‘label’ in an immunoassay can be radioactive, fluorescent, enzyme-based or a microparticle. Which is the most important attribute to consider when choosing a label? Labels should:
A. Be inexpensive to produce.
B. React chemically with another reagent during the assay to produce a change in signal.
C. Be free from interference by common matrices.
D. Produce a specific energy change that can be measured.
5. Cloned enzyme donor immunoassay (CEDIA) is a homogeneous immunoassay. Homogeneous immunoassays:
A. Can be mixed, incubated and read in the original container.
B. Require physical separation of the bound and free antigen.
C. Do not require physical separation of the bound and free antigen.
D. Are difficult to scale up to large automated analysers.
6. Positive immunoassay results in forensic toxicology must be confirmed by another technique such as GC-MS. The main purpose of this confirmation is to:
A. Definitively identify the antigen.
B. Measure the concentration of the antigen.
C. Determine which stereoisomer of the antigen is present.
D. Determine if the result is a true positive.
7. A cutoff is used in immunoassay to identify samples as either positive or negative. Urine cutoffs used in workplace drug testing:
A. Distinguish active drug users from those who have been passively exposed.
B. Distinguish drugs from compounds that can be produced post-mortem (e.g. biogenic amines).
C. Distinguish drug users who are impaired by drugs from those who are not.
D. Are set by an international oversight organisation.
8. Reference standards containing known concentrations of the antigen are used in immunoassay in order to:
A. Determine the antigen concentration.
B. Demonstrate that the technique is working properly.
C. Determine if the concentration of antigen is above or below the cutoff.
D. All of the above.
9. Enzyme-linked immunosorbent assay (ELISA) uses a colour change to identify the presence of an antigen. ELISA can be classified as either ‘direct’ or ‘indirect’. During direct ELISA:
A. The antigen is bound by a primary antibody, which is then detected by a labelled secondary antibody.
B. The antigen reacts directly with the label, producing a colour change.
C. The antigen is bound by a primary labelled antibody only.
D. The antigen is immobilised directly on the bottom of the microtiter plate well.
10. A toxicology laboratory receives samples of blood, urine and oral fluid from the same individual for cannabis testing by immunoassay. Only the blood and urine give a presumptive positive result for cannabinoids. Which is the best explanation:
A. The immunoassay targets the active ingredient in cannabis (THC), which is not found in oral fluid.
B. The oral fluid immunoassay test is a false-negative result.
C. The immunoassay targets the main cannabis metabolite (carboxy-THC), which is not found in oral fluid.
D. The blood and urine immunoassay tests are false-positive results.
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Footnote |
† Present address: Toxicology Unit, Imperial College London, Charing Cross Campus, St Dunstan's Road, London, W6 8RP, UK. E-mail: h.hamnett@imperial.ac.uk |
This journal is © The Royal Society of Chemistry 2018 |