The need to handle precise volumes of liquids for various applications make pipettes an essential tool in clinical and research laboratories. The use of these precision instruments and their proper handling will ensure reliable measurements. Factors that negatively impact a pipette performance are:
- Lack of trained operators
- Operator fatigue
- Heat transfer from the operator’s hands
- Air temperature and relative humidity
- Low quality pipette tips
- Malfunction of the device
Once the right instrument has been selected and the technique of pipetting perfected, it is important to ensure that the instrument is in good working condition all the time. Consistent calibration of the instrument is an essential laboratory best practice to ensure greater quality results.
The main objective of pipette calibration is to make sure that dispensing is carried out with the intended accuracy. The calibration process requires the use of equipment such as a beaker, an Erlenmeyer flask, pipette filler, a thermometer and a balance. The process should also be undertaken in monitored and recorded conditions by experienced individuals.
Calibration intervals are a matter of concern. According to the report in Laboratory News, pipettes checked yearly without any preventative maintenance or regular servicing procedures in place will have a 20% or more failure rate. Most manufacturers recommend calibrating the equipment at least once every six months. Critical applications may require monthly service. Nevertheless, the decision on calibration should be taken based on the knowledge, skill and training of the operators, how the device is handled, how intensively it is used, type of liquid dispensed, the required level of precision and accuracy, and instrument brand and type (reliable pipette brands may require less frequent calibration).
Preventive maintenance along with calibration on a regular basis will ensure that the instrument continues to function properly. Efficient preventive maintenance service would involve thorough cleaning and inspecting the working parts of the instrument, replacing grease and/or seals, checking for corrosion, and repairing and/or replacing parts as necessary.