Dried blood spot (DBS) testing is a microsampling method based on dried spots of whole blood. The technique is widely used in newborn screening programmes, to monitor patients with inherited metabolic disorders, and for the analysis of hundreds of molecules involved in health and disease, including nucleic acids, small molecule drugs, proteins, enzymes and antibodies (for an extensive overview, see Reference 1).
In a typical DBS testing workflow, blood is removed from an individual and immediately applied to a DBS filter paper for drying. In the laboratory, circular discs of a certain diameter are cut from the dried filter paper spots. These discs, also known as sub-punches, hold approximately 3-10 µL of blood, and serve directly as the sample for many downstream testing applications in microtitre plates.
Since DBS testing is often used in conjunction with sensitive applications, e.g., mass spectrometry, ELISA and PCR, blood volumes in the microlitre range are often sufficient. However, accurate analyses of low-concentration substances such as trace elements, or analysis of several analytes within the same sample, are often hampered by the low volumes of blood collected in DBS filter papers. In addition, the equipment in many routine laboratories is not developed for microsamples of only a few microlitres.
Capitainer®B 50 enables self-sampling of larger blood volumes with accuracy and precision
Last month, we launched Capitainer®B 50, a microsampling blood collection device that can collect and store 2 x 50μL of whole blood. This product compliments our existing portfolio of patented volumetric and precise self-sampling devices based on our proprietary quantitative DBS (qDBS) technology.
All of our card-based devices make it possible for patients to take their own sample with minimal/no help at home. The devices are used with an appropriate lancet to puncture the fingertip and draw capillary blood. The sample card measures a precise volume of blood that is automatically dried in a protected paper disc contained inside the device. The sample can then be sent as non-hazardous post by regular mail at ambient temperature to the appropriate testing lab.
Key features of Capitainer®B 50 include:
- Possibility to add multiple drops of blood. The proprietary filling mechanism employed in Capitainer®B 50 allows for the application of multiple blood drops, until the blood reaches the clearly marked stop line in the device. The possibility to add multiple drops allows patients to take their samples at their own pace, however the entire sampling process can be completed with ease within a couple of minutes from start to finish.
- Elimination of additive-induced assay interference or inhibition. Capitainer®B 50 does not contain anti-coagulants or other additives that could potentially cause assay-interfering effects.
- Precise filling mechanism. The microfluidic metering mechanism in the qDBS technology quantifies the blood volume with superior precision and accuracy. In addition, qDBS technology upon which Capitainer®B 50 is developed, causes a built-in delay in sample transfer to the DBS disc to give the user sufficient time to note correct filling to the stop line. Together, this ensures superb precision in filling volume (standard deviation less than 0.98 μl (CV < 2%).
- Sample protection. As with all other Capitainer cards, the sample disc in Capitainer®B 50 is embedded in the device, providing protection from the environment. This is in contrast to a standard DBS card, where the user can touch the card, as well as move it and place it on surfaces that may introduce contaminants.
- Instrument and assay compatibility. The increased volume capacity of Capitainer®B 50 is made possible by the use of a pre-cut sample disc that has the same diameter (6mm) as Capitainer®B, but with increased disc height. This feature ensures full compatibility with 96-well assay plates, our pre-analytical handler PH96, as well as automated workflows based on 96-well format.
Diverse applications in anti-doping, HIV monitoring, and testing in low-resource settings
Within DBS testing, the smallest possible sample volume is always best for patient comfort and convenience. However, reliable analysis of certain markers requires larger volumes, and in these cases, the option to sample more blood conveniently is necessary. The volume capacity of Capitainer®B 50 is five times greater than its predecessor, Capitainer®B, a technological advance that expands the range of possibilities for DBS testing.
Capitainer®B 50 is not limited to any particular types of tests, but some of the major application areas that will benefit from the increased sample volume include:
- The detection of low-abundance analytes that are difficult/impossible to measure accurately in low-volume DBS samples.
- Measurement of multiple analytes or biomarkers from the same sample. Such approaches may be very cost-effective in low-resource settings, allowing physicians to monitor several parameters of health and disease without increasing sampling costs, e.g., trace elements for nutritional analysis, from a single sample that can be prepared remotely and sent to an analytical lab.
- Larger blood volumes may allow for increased assay accuracy and sensitivity in certain assay types, e.g., quantitative PCR, which is widely used to monitor chronic viral infections such as viral load in HIV and certain hepatitis serotypes.
- Anti-doping testing. The World Anti-Doping Agency (WADA) requires a minimum total of approximately 40 µL and 20 µL of capillary blood in the so-called “A” and “B” spot(s) for chromatography-mass spectrometric analytical methods, which are used in routine monitoring of doping substance usage (2). The large and accurate sample volume collected by Capitainer®B 50 makes it an ideal device for DBS testing within anti-doping applications.
Learn more about how self sampling for dried blood spot testing works, or try Capitainer®B 50 for free
Capitainer®B 50 is part of a complete platform for self-sampling that we are building for blood, plasma, and urine. With Capitainer®B 50, it is possible to collect larger sample volumes for quantitative DBS testing than before, while ensuring device compatibility with existing laboratory assays, processes, and equipment. If you or your organisation is interested in testing Capitainer®B 50 in any of the applications mentioned above, or another application, please get in touch with us here to arrange a complementary sample.
Read the full press release about Capitainer®B 50 product launch here.
- Moat, S. J., George, R. S., & Carling, R. S. (2020). Use of Dried Blood Spot Specimens to Monitor Patients with Inherited Metabolic Disorders. International Journal of Neonatal Screening, 6(26), doi: 10.3390/ijns6020026.
- World Anti-Doping Agency 2021 Code Implementation Support Program Guidelines for Sample Collection. Accessed 9th January 2023.