How It Works: A Guided Pipetting System

Problem: Published studies, such as those documented by Artel®, have shown how a change in environmental barometric pressure creates volume variations, which alters the pipetting accuracy of air displacement pipettes. This effect is particularly noticeable when pipetting small volumes.

While a pipette may be brand new or recently returned from calibration, the pipette factory may be at a different altitude than the laboratory using the pipette. Integral to the mechanical design, the air spring within the air displacement pipette changes with this variation in barometric pressure. At higher elevations with inherently lower air density, less liquid is drawn into the tip and subsequently dispensed, resulting in under-delivery and inaccuracy when compared to factory calibration. Therefore, pipettes must be adjusted for the elevation at which they will be used to account for this natural phenomenon.

Most pipette applications require users to pipette multiple liquids to complete a process from sample preparation to analysis. This complicates pipetting as each fluid’s individual properties affect its liquid handling and must be accounted for to prevent poor accuracy and precision.

To manage the variety of liquid properties, technicians often calibrate separate sets of traditional pipettes for each fluid type; for example, labs contain one set of pipettes for viscous solutions, one set for volatile and one set for aqueous. Thus, a total of 9–12 conventional pipettes must be calibrated to complete a method from start to finish while ensuring the best liquid handling for each fluid used. Having to use multiple sets of pipettes is both cumbersome and costly due to the calibration maintenance required.

Solution: One option to solve such problems is Hamilton Company’s Microlab 300 Series Pipettor, which was developed to bring semi-automated liquid handling and compensation technology into the hands of laboratory technicians. The Microlab 300 is used in place of conventional manual and electronic pipettes as it adjusts for elevation and is able to instantly compensate for each liquid used throughout an entire pipetting application.

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