A serological pipette is more accurate than a graduated cylinder for measuring small volumes of liquid.
There are a few reasons for this:
– Graduations – Serological pipettes have finer gradations, usually in increments of 0.01 mL, compared to 0.1 mL graduations on most graduated cylinders. This allows for more precise volume measurements.
– Measurement range – Serological pipettes typically measure from 0.1 mL to 1 mL volumes. This narrow range with fine graduations improves accuracy for small volumes. Graduated cylinders measure larger ranges less precisely.
– Readability – The long thin pipette tip provides a narrow liquid column that magnifies the meniscus for easier and sharper reading. Cylinders have wider diameters that make the meniscus harder to read accurately.
– Precision – Serological pipettes made from glass are individually calibrated to have measurement tolerances within +/- 0.02 mL or better. Graduated cylinders often have tolerances of +/- 0.1 mL.
– Technique – The controlled filling technique for pipettes is simpler than carefully filling a cylinder for maximum accuracy.
– Reproducibility – Measurements are more reproducible with serological pipettes, giving better experimental repeatability.
So in summary, the fine graduations, narrow measurement range, improved readability, calibrated precision, and control technique of serological pipettes allow for more accurate and reproducible small-volume liquid measurement compared to graduated cylinders. Serological pipettes are the preferred choice when accuracy matters.
