All centrifugation of coagulation tests in our department had been performed at 4oC as earlier centrifuges raised temperatures of samples to unacceptable levels. In reporting our evaluation of a new centrifuge, the ThermoScientific -Megafuge 40R, we noted 3 design flaws and explored solutions to these as well as determining the optimum temperature for centrifugation of samples for coagulation testing and how this relates to the setting on the centrifuge.
Some laboratories centrifuge coagulation samples at room temperature (RT). RT is a misleading term, with many differing ranges quoted in a variety of Australian Standards. We define room temperature as 20oC to 24oC. Results of centrifugation in a non-temperature controlled centrifuge showed that post centrifugation samples were on average 27.1oC, that is, they did not remain at ‘room-temperature’.
In a temperature controlled centrifuge used in another section of the laboratory, post centrifugation samples were on average 21.3oC.
Using the ThermoScientific -Megafuge 40R, we measured the bowl temperature, the centrifuge sensor temperature, the sample holder and the sample temperature over a range of temperature settings (4oC, 10oC, 17oC and 20oC) at pre-spin, post-spin, and 10 mins and 30 mins post spin and also noted the level of condensation in the centrifuge bowl at each temperature setting.
All samples completed their centrifugation at a temperature higher than the set temperature of the centrifuge at a predictable and reproducible level.
In conclusion, centrifugation at a setting of 17oC-20oC gave optimal results.