This application note discusses one approach for optimizing pipetting accuracy on a Beckman Coulter Biomek liquid handler using the MVS Multichannel Verification System. Pipetting accuracy can be improved in any number of ways, such as by adjusting individual liquid class variables (aspirate rates, dispense rates, air gaps, mix steps, etc.) and measuring transferred volume resulting after each successive adjustment. In the optimization approach discussed here, however, the individual and unique liquid class variables within a technique are relatively unimportant to the optimization process. The focus of this application note is to show that pipetting accuracy can be improved by simply adjusting the linearly-based calibration factors within the technique1 by first knowing: (1) the scaling factor and offset volume employed within the technique for the volume transfer task and (2) the amount of volume transferred to the test vessel as measured with the MVS. In the example discussed, a pre-optimized arbitrary “universal” pipetting technique was employed to dispense 2, 5 and 8 μL (scaling and offset were 1 and 0, respectively). The “as found” performance was (linearly) inaccurate: -27.85%, -14.68% and -9.6% respectively for the three volumes. New scaling and offset values were calculated and the instrument was retested with the new values to show an improved relative inaccuracy at each volume: -0.05%, -1.14% and 1.05%, respectively.
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