Beckman Coulter Biomek NX
A Beckman Coulter Biomek NX liquid handler can be optimized for pipetting accuracy by adjusting the scaling factor (slope, m) and the offset (y-intercept, b) in the Biomek software’s Calibration tab within the Technique Editor. The calibration is based on y = mx + b. The scaling factor and offset values are meaningless, however, without a way to measure volume transfer accuracy.
Adjusting pipetting accuracy is a simple and effective process: (1) measure volume transfer performance (three or more target volumes are recommended); (2) plot measured (x) versus theoretically displaced volume (y); (3) determine the new slope and offset values; and (4) enter values and retest. A default preoptimized universal technique was employed to dispense 2, 5, and 8 µL. The preoptimized performance was (linearly) inaccurate: -27.85%, -14.68%, and -9.6%, respectively.
New scaling and offset factors were calculated and employed, and the relative inaccuracies improved to -0.05%, -1.14%, and 1.05%, respectively. The example above is represented graphically using the mean volumes measured for preoptimized and optimized trials (Figure 1).