( inal mix settings. ...)Serial Dilution with the Bravo Liquid Handling Platform

Serial Dilution by Row
The Bravo can perform serial dilutions by column and by row. While all of the previous experiments were serial dilution by column, it was necessary to confirm that the serial dilution by row would work equally well. Table 6 shows that by applying the improved mix parameters, high precision and accuracy was possible in another serial dilution method. Average precision was improved mostly due to the fact that there were seven dilutions instead of 10; error was propagated over a fewer number of dilutions. With fewer dilutions, the overall serial dilution time decreased as well.

Conclusions
This study shows that the Bravo can quickly and reliably serial dilute across columns or rows of a plate. Based on these experiments, the following settings gave us low CV and an accurate overall dispense. It is possible to achieve accurate and precise serial dilution results in a short process time with:
No tip changes
A minimum number of mix cycles
No wash steps

The ability of the Bravo to do serial dilution with a 96 or 384 channel disposable tip head means that serial dilution can be performed with one instrument with one head type. A head swap is not necessary. A parameter setting in the protocol allowed a change from transferring liquid with the entire head to transferring with a single row or column.

Serial dilution experiments can be optimized through a number of different parameter changes, and based on the results shown here, the keys to obtaining accurate and precise mixing are the following, in order of decreasing contribution to overall mixing efficiency:
Maximize volume of mixing
Maximize mixing speed
Maximize the area traversed by tip retraction/extension. '"/>

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