The effects of resting time, centrifugation time, and technician training on plasma sample quantity and quality:...

The Dog Aging Project (DAP) is a large-scale longitudinal study for studying aging in dogs. For some dogs in the DAP, blood samples for plasma isolation are collected by non-DAP personnel. However, plasma samples are sometimes inadequate, eg, insufficient volume for assays.

We aimed to examine three factors that may affect plasma yield: resting time after sample collection, centrifugation time, and level of operator or technician training.

We designed three experiments using a convenience sample of 5 dogs. Each experiment varied one of the three factors and held the other two constant. Experiment 1 examined 5 different resting times: 10 minutes and 1, 4, 24, and 72 hours. Experiment 2 compared centrifugation times of 7 and 14 minutes. Experiment 3 compared trained and untrained personnel. Sample resting was always under refrigeration. Experimental outcomes were total plasma volume, number of successful aliquots, hemolysis, and lipemia.

A resting time of 72 hours yielded statistically significantly lower plasma volume than resting times ≤ 4 hours. Resting times of 24 and 72 hours also had statistically significantly higher hemolysis scores compared with other resting time points. In addition, trained operators or technicians yielded an average of 0.5 more aliquots. Outcomes were similar by centrifugation time in Experiment 2.

To mitigate sample loss, we recommend shorter post-collection resting times and ensuring technician proficiency. Additionally, increasing the requested whole blood volume may improve sample yield.