Optically gated vacancy electrophoresis in microfluidic devices Original Research Article

Electrophoretic vacancy separations with optically gated injections are presented as an alternative method of performing separations in microfluidic devices. Vacancy electrophoretic separations of FITC-labeled amino acids have been performed over a separation distance of 0.9 cm at a field strength of 353 V/cm, with an injection every 8.0 s. For a series of 10 vacancy electrophoretic separations with 100-ms (177 pl) optically gated injections, the RSD for retention times was 0.17% and the RSD for peak height was 1.6%. The performance of optically gated vacancy electrophoresis has been quantitatively compared to the performance of standard optically gated electrophoresis for the same separation using the same microfluidic device and identical experimental conditions. For these separations, the overall performance of the two optically gated injection methods is similar. The resolution obtained with the electrophoretic vacancy separations was slightly lower (6–14%) than with the standard electrophoretic separations due to the larger injection volume for optically gated vacancy injection, using the same injection time.