sample storage factors when using dried microsamples
by Neoteryx | 2 min read
Using dried microsamples collected through fingerstick sampling for research studies can often replace the traditional practice of using venipuncture to collect liquid blood samples in vials. Dried specimen microsampling reduces biohazard risks while also increasing the feasibility of sample storage and shipment. However, the question arises about how long dried specimen samples can be stored.
Wet Blood Samples vs. Dried Blood Samples
Collection and Storage
For wet blood tests to be accurate, the samples must be collected, stored, and transported in specific ways. These factors affect their long-term viability. Wet blood samples should be tested soon after collection; usually within four hours.
When serum samples are required for testing, they must be separated from whole blood within two hours after sample collection. Depending on the test, additives are sometimes used, which affect sample testing and storage.
Blood sample storage requires specific temperatures depending on the type of study for which the samples will be analyzed. The samples may be stored at room temperature (about 20°C), refrigerated (approximately 40°C), or frozen (32°C or below).
Length of Storage
Six weeks has long been considered the blood sample “shelf life” by blood banks. However, a new study shows that red blood cells become less effective in supplying oxygen-rich cells in the body within 3 weeks of storage. Extended storage of blood in frozen or refrigerated temperatures can hinder its viability.
Advantages of Using Dried Samples
Due to these challenges encountered with wet sample collection, many researchers have switched to dried blood sampling for research and clinical trials. One advantage is that researchers can remotely collect samples from geographically diverse populations when using dried blood spot (DBS) methods. With a dried sampling approach, study participants don’t have to visit a clinic or research site for professional assistance with sample collection. They can use an easy finger-stick method for remote specimen collection at home.
Dried blood spot sampling works well with the finger-stick method, but DBS cards also present some challenges, including lack of sampling accuracy and spot area visibility due to hematocrit effects. These issues have prompted researchers to explore more advanced methods of dried blood sampling: the volumetric absorptive microsampling technique enabled by Mitra® devices equipped with special VAMS® tips.
These absorb the precise sample volume needed for clinical studies. The samples collected using the Mitra devices don’t require special handling. They are housed inside a protective plastic cartridge immediately after collection. They are slipped into a sealed specimen pouch that includes a sachet of drying desiccant, which allows them to dry while in transit to the lab.
Since study participants can collect their samples at home, dried microsampling allows for remote research studies. Remote or decentralized studies were previously less feasible because of the challenges associated with collecting, handling, and storing wet specimen samples. More researchers are finding that Mitra microsamples are easy to use and store with robust sample stability. They can reference the published literature for guidance on sample storage timelines based on the experiences of other researchers working with various analytes or assays. Most importantly, dried volumetric absorptive microsamples provide the precision needed for accurate scientific analysis.