Pipette Calibration Requires Different Types of Balances
Many users of pipettes do not realize that distinct balances are required to calibrate different pipettes. If you are currently using an onsite pipette calibration provider, you should take note of the measurement equipment your provider carries into your lab. Depending upon the equipment used, you may be settling for a great deal of unnecessary measurement uncertainty. Most of the time, on-site companies are limited to the use of improper balances to calibrate your pipettes. Unfortunately, many calibration service providers attempt to use a one-size-fits-all approach when calibrating pipettes, and the quality of calibration suffers as a consequence.

According to the science of Metrology, several balances with varying sensitivities are to be used for each volume range of pipette. Thus, one way to identify a sub-par calibration service is by monitoring the balances that service providers use. A provider entering a laboratory with only one balance should serve as a red flag indicating that the calibration underway is likely not of the highest quality and not highly reliable, leaving you with more uncertainty than you started with!

Identify the Correct Balance for the Weighing Task 

The ISO 8655 standards specific for pipette calibration, (Figure 1) defines the minimum requirements for the resolution of balances, based on pipette volume. For instance, 0.1 mg resolution is sufficient for pipettes ranging from 100 uL to 1 mL. However, this resolution is inappropriate for any pipette volume below 100 uL. For pipettes with volumes of 100uL to 10uL, balances need a Semi-Micro Balance with 0.01 mg resolution. Accordingly, as the volume of the pipette gets smaller, the resolution must get smaller and more precise in order to deliver trustworthy data. For pipettes delivering below 10uL, proper calibration requires a 7- place Ultra Micro Balance with resolution of 0.001 mg. These balances are not made for transport.

Precision is of the utmost importance in most experiments involving pipettes, and use of high-resolution balances during the calibration process minimizes the uncertainty associated with pipette measurements. Several other factors, in addition to balance type, are also critical for getting the most out of pipette calibration. At TTE, we meet the high ISO 8655 standard by using the correct balances for different pipettes - unlike many of our competitors. We also perform our calibrations in recommended environmental conditions and have invested thousands of dollars to create a controlled laboratory that maximizes the potential of calibration and ensures that our customers can rely on the measurements their pipettes provide. Our 24-hour calibration service makes correct and accurate calibration convenient for all customers.