2.5. Verification Study
Human blood samples were used to check the reference range and confirm that the method was useful for analysis of a large number of human blood samples. Before and after each day’s run of human blood samples, a 150 μL sample of SRM 966 was analyzed, and the results were used to formulate a control chart. Quality control limits were set at two standard deviations from the mean. Runs where the SRM value fell outside the three standard de-viation control limits were removed and the samples done that day re-analyzed after a recalibration. The samples for the verification study were done in duplicate. If more than 10% error was observed between duplicate samples, the samples were reanalyzed. Data from the control chart were tracked to observe between day precision.