Analyst qualification for compliance with normal analytical practice for pipette use

Aim. This work aimed to assess the proficiency of routine medicine quality control analysts for compliance with the normal analytical practice (NAP) requirements for the standard pipette aliquoting analytical procedure. Materials and methods. Certified 2 mL Mohr pipettes provided by the proficiency testing provider; a gravimetric procedure for determining the delivered volume and the corresponding equipment that meets the ISO 4787:2021 requirements; methods of mathematical statistics. Results and discussion. The participants conducted five measurements of the delivered volume using the gravi-metric method. The acceptance criteria for the results were developed to ensure reliable verification of volumetric glassware, where the random analyst’s error had to be insignificant compared to the requirements for the error of the volumetric glassware, as well as compliance with NAP in routine analysis, particularly regarding individual deviations. A total of 64 analysts from 22 laboratories participated in the testing. Of these, 61 analysts achieved satisfactory results by all criteria. For 44 % of the participants, the deviations from the nominal value were signif-icant as per the ISO requirements for Class A pipettes. Individual and average deviations from the nominal value were calculated and analyzed, allowing for assessing the participant results’ precision and the correctness of their decisions regarding the ISO requirements for measuring equipment. The accuracy of the participants’ calculations, the instruments used, and the testing conditions were evaluated. Issues with calculations, rounding of results, and non-compliance with the requirements concerning metrological balance qualification, thermometer calibration, laboratory environmental conditions, and pipette condition evaluation were revealed. Conclusions. Findings indicate that participants can meet NAP requirements and perform pipette verification with high reliability, which aligns with the key analyst qualification requirements. The results confirm that for personnel qualification, it is necessary to use pipettes with certified delivered volume with acceptable uncertainty. The devel-oped testing procedure can be used for intra-laboratory proficiency testing