Compared to in-clinic sample collection, in-home sampling has many advantages. It saves time for patients, especially those who may be prohibitively far from a clinic or lacking adequate transportation. Additionally, sick patients can collect their own sample without the risk of spreading contagious illnesses. For labs and researchers, broader studies may be performed with fewer restrictions on geographical area. Compliance tends to be higher as the process is simpler for patients. Using dried blood as a matrix helps alleviate stability concerns during shipping compared to biofluids such as liquid blood or saliva.
Dried blood spot analysis is a familiar process but it faces challenges in absolute quantitation. It can be non-trivial to control the extract volume contained in a drop, and varying hematocrit levels between individuals will affect the analye concentration within a fixed area of a spot. To combat these challenges, volumetric adsorptive microsampling (VAMS) has been developed. In this technique, blood from a finger stick is wicked into a sampling tip with a fixed volume. The tip is dried and can be shipped off for analysis.
VAMS faces its own challenges, especially regarding consistent recovery. Hematocrit levels and age of the sample can lead to variable recovery. A variety of extraction conditions were tested on a panel of small molecule analytes to determine if a universal extraction was possible, or if trends could be established. Here, we will discuss these findings and their predictive value in determining optimal extraction conditions for a target analyte.
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- Advantages and challenges for VAMS in bioanalysis.
- Factors to consider during method development using VAMS
- The impact of various extraction conditions for a range of small molecule analytes of varying polarity to determine if recovery from the tips can be normalized across a variety of sample conditions.
- Trends in recovery which may predict optimum extraction conditions based on physical properties of the analyte.