The effects of resting time, centrifugation time, and technician training on plasma sample quantity and quality: Implications for the Dog Aging Project

Background: The Dog Aging Project (DAP) is a large-scale longitudinal study of 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, which can lead to, for example, insufficient volume for assays. Objective: 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. Methods: We designed three experiments using a convenience sample of five dogs. Each experiment varied one of the three factors and held the other two constant. Experiment 1 examined five different resting times: 10 min and 1, 4, 24, and 72 h. Experiment 2 compared centrifugation times of 7 and 14 min. Experiment 3 compared trained and untrained personnel. The sample resting was always under refrigeration. Experimental outcomes were total plasma volume, number of successful aliquots, hemolysis, and lipemia. Results: A resting time of 72 h yielded statistically significantly lower plasma volume than resting times ≤4 h. Resting times of 24 and 72 h 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. Conclusion: 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.