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.
First, the Guided Pipetting System prompts users upon initial startup to input the laboratory’s altitude to eliminate errors caused by variations in barometric pressure. Secondly, the product eliminates recalibration of multiple pipettes for each liquid used by providing a single pipette that achieves the accuracy and precision across the entire pipetting range (0.5 μL–1 mL). Lastly, standard and customizable Liquid Classes enable users to pipette even viscous and volatile fluids one after the other with acceptable accuracy.
Three standard Liquid Classes covering the range of liquid properties are provided with the instrument (i.e., volatile, viscous, aqueous) to quickly approximate pipetting parameters like aspiration and dispense speeds, delays and air gaps. Custom Liquid Classes can also be gravimetrically created to fine tune liquid handling of more challenging fluids. During the protocol programming, users simply select the Liquid Class that will be used at each step in the application. At execution, the Microlab 300 automatically implements the appropriate pipetting parameters per each task’s specified Liquid Class.
In all, a product such as the Microlab 300 optimizes liquid handling and reduces pipetting errors by providing quick elevation adjustment and an efficient, single-probe solution that requires no additional run-time and user intervention to complete an entire method with multiple liquids.
For more information, go to: www.hamiltoncompany.com/microlab300