Accurate liquid handling underpins every result a laboratory reports, from diagnostic pathology testing to a school chemistry practical. Accuracy depends on more than the pipettor alone. The pipette tip fitted to it plays an equally important role in delivering a true, repeatable volume. This guide explains how to choose a pipettor and pipette tips suited to the task, the user, and the standards Australian laboratories are expected to meet.
What Is a Pipettor and Why Does Accuracy Matter?
A pipettor is a handheld instrument that draws up and dispenses precise volumes of liquid, usually measured in microlitres. In clinical, pathology and research settings, even a small volume error can alter reagent concentrations or affect an entire test batch.
Most laboratory pipettors work on the air displacement principle, using a piston to create a vacuum that draws liquid into a disposable tip. Accuracy and precision are distinct properties. Accuracy describes how close a dispensed volume is to the true value, while precision describes how consistent repeated dispenses are with one another. A pipettor can be precise but inaccurate if it consistently under or over dispenses by the same margin. For school science, a small accuracy error may go unnoticed. In a pathology or research laboratory, the same error can invalidate a result or a whole assay run.
What Types of Pipettors Suit Different Laboratory Tasks?
Single-Channel or Multichannel?
Single-channel pipettors suit general bench work where samples are handled individually, such as reagent preparation, sample dilution and routine dispensing. Multichannel pipettors, typically in 8 or 12-channel formats, are built for plate-based workflows including ELISA testing and PCR setup, where dispensing the same volume across many wells at once saves time and reduces the chance of inconsistency between wells.
Manual or Electronic Pipettors?
Manual pipettors remain the standard for low to moderate volume work and are straightforward to maintain and calibrate. Electronic pipettors use a motor to control aspiration and dispensing, which improves consistency across users and reduces the thumb force needed for repetitive tasks. Laboratories setting up a new bench or replacing older equipment should compare single and multichannel options across a range of volume capacities to find the right fit for their workflow before committing to a purchase.
Why Does the Pipette Tip Matter as Much as the Pipettor?
A pipettor cannot deliver an accurate volume through a poorly fitted or low-quality tip. The tip forms the seal that maintains vacuum during aspiration, so its manufacturing tolerance directly affects the volume actually dispensed.
Tips vary in material, moulding tolerance and fit, and mixing brands can introduce a poor seal that no amount of pipettor calibration will correct. Filter tips are recommended wherever aerosol contamination is a risk, such as PCR work or handling infectious samples, because the filter barrier protects both the pipettor and the sample from cross-contamination. Colour-coding by volume range helps reduce user error at the bench, and certified RNase and DNase-free tips are essential for molecular biology applications. For routine microlitre-range work, a correctly sized tip in the 50 to 1000 microlitre range is a common choice where a consistent seal against a compatible pipettor is needed to preserve day-to-day accuracy.
How Do You Choose the Right Pipettor and Tip Combination?
Match the Volume Range to the Task
Selecting a pipettor with a volume range too broad for the task reduces accuracy at the lower end of its scale. Fixed-volume pipettors suit repetitive single-volume tasks, while variable-volume pipettors offer flexibility across a defined range. Reviewing the typical volumes used in a protocol before purchasing avoids under or over-specifying equipment.
Consider Ergonomics for High-Volume Use
Repetitive pipetting performed for extended periods each day can constitute a hazardous manual task under Australian work health and safety guidance, given the repetition, sustained grip and awkward wrist posture involved. Lightweight, low-force and electronic pipettors reduce this risk for staff who pipette frequently, and rotating tasks or scheduling short breaks further supports safe, sustainable use across a busy laboratory or teaching bench.
How Should Pipettors Be Maintained and Calibrated?
Pipettors are mechanical instruments with seals and springs that wear with use, so accuracy drifts over time even with careful handling. Regular calibration by a NATA-accredited laboratory provides traceable evidence that a pipettor is performing within its specified tolerance. Most laboratories schedule formal calibration annually, supported by simple in-house gravimetric checks between services to catch drift early. Replacing worn seals, storing pipettor’s upright, and avoiding cross-contamination between users all extend the interval between adjustments and support consistent results.
What is the difference between air displacement and positive displacement pipettors?
Air displacement pipettors use a cushion of air between the piston and the liquid, suiting most aqueous samples. Positive displacement pipettors use a piston that contacts the liquid directly through a capillary tip, making them better suited to viscous, dense or volatile samples where air displacement can lose accuracy.
How often should laboratory pipettes be calibrated in Australia?
Pipettor calibration intervals depend on factors such as laboratory quality requirements, instrument usage frequency, risk assessment, regulatory expectations and manufacturer recommendations. Many laboratories establish scheduled calibration programs through qualified providers, including NATA-accredited laboratories where applicable, and use routine verification checks such as gravimetric testing between services to identify performance changes early.
Can any pipette tip be used with any pipettor?
No. Pipette tips should be compatible with the pipettor model and designed to create a secure seal during aspiration and dispensing. An incorrect fit can allow air leakage, affecting volume accuracy and repeatability even when the pipettor itself is correctly calibrated.
Why do pipette tips come in different colours?
Colour-coding indicates the intended volume range of the tip, helping laboratory staff quickly identify the correct tip for a given pipettor and reducing the chance of selecting an incompatible size during busy bench work.
References:
National Association of Testing Authorities, Australia (NATA) 2021, Piston operated volumetric apparatus (POVA/pipette) calibration, NATA, Sydney, viewed 17 September 2026.
Safe Work Australia 2020, Model code of practice: hazardous manual tasks, Safe Work Australia, Canberra. viewed 17 September 2026.
