[Establishment of Internal Quality Control Method for Mixed and Split Samples by NAT in Blood Donor Screening]

To establish and evaluate the methods of internal quality control in blood donor screening by nucleic acid test (NAT).

After HBV-DNA standard quality control (QC) sample (60 IU/ml) was diluted by pooling 6 samples, the concentration was 10.0 IU/ml, which was approach twice of the low limit. When the pooling result turned out reactive, the pooling samples need to be split into single sample to process. Meanwhile, the standard QC samples were tested as well. The same batch QC samples were tested 20 times respectively, calculate the mean (x̄), standard deviation (SD) and CV. Make Levey-Jennings QC curves by setting x̄±2SD as warning, x̄±3SD as rejected. The Levey-Jennings quality controls chart was mapped by using Microsoft Excel.

After 20 times test of mixed/split samples, the x̄±2SD were 33.03±1.47 and 30.08±0.98, the x̄±3SD were 33.03±2.20 and 30.08±1.47, the CV were 2.22% and 1.63%, respectively. The P value of t test was 0.08 and 0.17 respectively, there was no statistically significant difference between the 2 group.

When establish an internal QC system in the screening laboratory by nucleic acid testing, the concentration of the QC samples should be equal to normal specimens. This type of QC system may validate the extraction and amplification of the nucleic acid, and improve the stability of the test results.