2018 Volume 67 Issue 1 Pages 44-51
Micropipettes are often used to dispense or dilute both patients’ and control samples. Whereas handling of micropipettes is very simple and enables one to take proper amounts of samples rapidly, it is essential to use them exactly according to the operating manual to maintain dispensing accuracy. In this study, we investigated whether the method of manipulating micropipettes affects the accuracy of divided injection by verification experiments including a questionnaire survey to determine the actual status of the manipulation method. We demonstrated that it was excellent both in terms of accuracy and reproducibility if the micropipette with the total capacity near the collection quantity is selected. Moreover, pre-wetting contributed to the improvement of the dispensing accuracy. Forward pipetting (FP) provided higher accuracy of divided injection than reverse pipetting (RP). FP provided a lower value, whereas RP provided a higher one than the theoretical value. FP showed higher reproducibility for water and RP for serum. Therefore, we should basically select FP. However, we should select RP for samples with hyperviscosity. We also found that a large difference in temperature between the tip of the micropipette and the sample affected dispensing accuracy. Various methods of divided injection were used in 91 institutions. In the future, we hope that each institution will keep the manual of the micropipettes used.
