At the Department of Forensic Medicine, Faculty of Medicine, Fukuoka University, forensic toxicology is conducted as part of forensic autopsy investigations. For the concentration and evaporation steps in the sample pretreatment process for screening and targeted drug analysis, the laboratory has incorporated the TurboVap® LV high-throughput nitrogen blowdown evaporator into their analytical workflow. In this interview, we spoke with Senior Assistant Professor Brian Waters, who has been using the TurboVap® LV and positive pressure manifold Biotage® PRESSURE+ 48 in his routine work.
Brian: I am involved in drug analysis in the Department of Forensic Medicine at the Faculty of Medicine, Fukuoka University. I studied textile chemistry at North Carolina State University, where I became interested in forensic science, and later obtained a Master of Science in Criminalistics from California State University, Los Angeles. I also spent time working as a Criminalist with the County of Los Angeles Department of Coroner-Medical Examiner. However, I always wanted to return and work in Japan, and through a timely opportunity, I joined Fukuoka University in April 2011 as an Assistant Professor in the Department of Forensic Medicine.
In our department, we work closely with the police, and our primary role is to analyze body fluids and tissues collected during forensic autopsies. We examine which drugs may be present in biofluids such as blood, urine, and bile, as well as in organs such as the kidneys and liver. When necessary, we also perform quantitative analysis of the detected substances and provide this information to the pathologist to help determine the cause of death.
Brian: We use analytical instruments such as GC/MS and LC/MS, and the TurboVap® LV is used in the pretreatment step prior to analysis, specifically for concentration and evaporation of drug extracts. To improve analytical sensitivity, we concentrate or dry down and reconstitute the extract before injection.
Brian: Yes. Our extraction solvents often contain formic acid or acetic acid, so we selected the PTFE-coated model for its acid resistance. With the aluminum heat-block type evaporators we used previously, the acidic solvents would corrode the metal, causing rusting and contamination. As a result, we frequently had to take the nozzles out for cleaning or replacement. With the PTFE-coated TurboVap® LV, that problem has been eliminated, significantly reducing the time and effort spent on maintenance.
Brian: Our previous instrument used an aluminum heat block, whereas the TurboVap® LV uses a glass water bath. We set the bath temperature, place the tubes inside, and apply nitrogen. Because the glass is transparent, we can easily check the remaining sample volume at any time. With our old heat-block system, we had to lift each tube out to see how far the concentration had progressed, which made the workflow quite time-consuming.
Additionally, the system allows simple method setup to create customized evaporation methods. For example, during the initial stage when the sample volume is still high, we can apply a gentle nitrogen flow to avoid splashing, then increase the flow rate as the solvent level drops to accelerate evaporation. The ability to set up and save these methods is extremely convenient.
Brian: The instruments we previously used blew nitrogen gas straight down onto the sample surface through a nozzle positioned vertically above the liquid. In contrast, the TurboVap® LV directs nitrogen in a spiral pattern along the inner wall of the test tube, and the gas reaches the sample surface while creating a vortex. This improves concentration efficiency, and the concentrated residue settles cleanly at the bottom of the tube.
With vertical-blow instruments, residue often sticks to the tube walls, and if the gas flow is not well controlled, droplets may splash back and contaminate the nozzle. As a result, the nozzles need to be cleaned frequently.
Because the TurboVap® LV ’s nozzles do not extend deep into the tube, they are far less likely to be contaminated, allowing us to maintain cleanliness with minimal effort. The difference in nozzle structure also makes routine maintenance much easier. Previously, the long nozzles reached deep toward the bottom of the test tube, so if we lowered them too close to the liquid surface, contamination occurred. And as the solvent level dropped during concentration, the operator had to manually lower the nozzle further, sometimes resulting in the nozzle dipping into the sample. The vortex-based evaporation method completely solves this problem.
Another advantage is the shortened evaporation time. Aqueous samples in particular require long evaporation times. With aluminum block–type evaporators, we often had to heat samples at 60–80°C for an extended period, but with the TurboVap® LV, a water bath temperature of around 42°C is sufficient for efficient evaporation.
Brian: There is another point I really appreciate. The TurboVap® LV is fully digital, and the temperature can be set via the touch panel, allowing us to specify the exact temperature in 1°C increments. With the analog systems we used before, temperature control was unstable, and there were times when the actual temperature differed from the set temperature by as much as 5°C.
Another advantage is the flexible rack system. Previously, we had to use racks tailored for each test-tube diameter, which was inconvenient when multiple researchers shared the evaporator. For example, I often use 16 mm tubes, while my colleague might use 13 mm tubes, and we could not run samples at the same time. With the TurboVap® LV’s flexible rack, tubes of different diameters can be used together. By adjusting rack height, tubes of different lengths can also be used together. This has made our workflow significantly more efficient.
I would like the nitrogen gas blowdown to stop automatically when the sample reaches the target volume. In drug analysis, quantitative accuracy is sometimes required, so having all samples finish at the exact same volume would improve usability even further.
(End-point detection feature is available on the TurboVap® II, which operates with dedicated 50 mL or 200 mL concentration tubes and accommodates up to six samples.)
We would like to sincerely thank Senior Assistant Professor Brian Waters as well as the team at the Department of Forensic Medicine, Faculty of Medicine, Fukuoka University, for their valuable opinions and continued support for the Biotage portfolio of products.
Note: This interview was first published in Japanese in October 2019.
Literature number: CC01