For the gravimetrically determined dispensing of the Sciclone HVH, weights dispensed were corrected for evaporation. The magnitude of evaporation over the 90 second experimental time frame can be seen for all sample types in Figure 2: A and B.
Since this is a wet transfer and there is sample in the plate at the start of the experiment, an evaporation rate of >100% at 1 μL is possible. During the course of our experiments, with water taken as the "standard" sample type, we see that most samples, with the exception of Ethanol and DMSO, did not have evaporation rates that varied by more than 2-3% from water (Fig. 3).
In addition to the %CV data generated, it was also noted that the behavior of BSA solution was not ideal under the experimental conditions used here. At 20 μL/sec as an aspiration rate, small bubbles formed. Although this did not affect the precision greatly, the surface tension properties of bubbles are known to damage proteins1.
At pipetting volumes >5 μL, plate-to-plate %CV's attained for the Sciclone 3000 ALH were <1%. In the 1-2 μL range, a CV of <2.5% is possible with the proper pipetting technique. The addition of a surfactant (Triton X-100) dramatically improved the precision, possibly due to better wetting properties2 . This is particularly clear at 1 μL, where the CV is close to 1%. Since different liquids accountant for more than a 4% change in CV (at 1 μL), this demonstrates that variability in sample properties introduces more error into pipetting protocols than is inherent in the precision of the Sciclone ALH High Volume Head device (<3% CV). These results indicate that slight modifications to sample solutions can yield better pipetting results. Although the method for compensating for or eliminating backlash will not have an e