Liquid transfers were evaluated in-house using 10 previously determined optimization parameters, including air gap, blow out, aspiration and dispense speeds, overstroke, and tip height. These were subsequently evaluated using a multichannel verification technique—a dual-dye multichannel verification system that has been widely used in the automation field to calibrate liquid volumes from a variety of automation platforms. This system offers a systematic validation of the liquid-handling instrument and includes dye solutions (sample and diluent), a calibration plate, an orbital plate mixer, as well as spectrophotometric read-out and data-analysis software.
The single-, 8-, and 12-channel heads were used to dispense three different volumes: 2, 3, and 30 µL, to evaluate accuracy over a wide range. In addition, the 96-channel head was used to dispense five volumes, from 0.5 to 30 µL, in order to determine that this new liquid handler can dispense liquids in a precise and accurate manner. The assessment of these parameters is critical to generate reliable data when using the instrument for automated applications.
The accuracy of the Versette was initially confirmed via the following process:
- Dye was dispensed at the selected volume into a 96-well plate.
- The plate was shaken at 1,200 rpm for one minute and centrifuged at 1,700 rpm for one minute.
- Spectrophotometric absorbance was measured.
The coefficient of variation (%CV) and margins of error (%error) were subsequently calculated using multichannel verification system software.