Pipetting Performance across Laboratory Personnel: A Comparative Study

Background: Accurate and precise pipetting is critical for reliable laboratory results, especially when handling small volumes or sensitive analytical techniques. Despite the common use of piston-operated pipettes, operator-dependent variability remains a major source of error. This study aimed to evaluate pipetting performance among laboratory personnel with varying levels of experience. Methods: The study included 108 participants: 26 laboratory school students (first to third year), 10 PhD students, 10 clinical chemists, and 62 laboratory technicians. Technicians were stratified into 3 groups based on the extent of sensitive manual pipetting in their work: minimal (Group A), moderate (Group B), and high (Group C). Pipetting performance was evaluated using gravimetric replicates at 10 µL and 100 µL volumes, and a dilution task involving serial dilutions of 1 M copper sulfate. Accuracy and precision metrics were compared across groups. Results: The median coefficient of variation (CV%) was lower for 100 µL replicates (0.3% to 0.8%) than for 10 µL replicates (1.4% to 5.9%). Laboratory students showed the greatest variability and longest task completion times, although performance improved with advancing school year. Ten percent of participants exceeded ISO-defined accuracy limits for 10 µL pipetting, and 22% for 100 µL. Imprecision limits were surpassed by 36% and 20% of participants for 10 µL and 100 µL, respectively. Group C technicians achieved optimal dilution performance (R2 = 1.00), while students showed the highest deviation. Conclusions: Pipetting performance was significantly influenced by experience level and task sensitivity. Even experienced personnel occasionally failed to meet ISO standards, underscoring the need for ongoing training and performance assessment.