Automated sample preparation for electrospray ionization mass spectrometry based on CLOCK- controlled autonomous centrifugal microfluidics

We report a centrifugal microfluidic device that automatically executes sample preparation at steady-state rotation for clinical applications using mass spectrometry. The autonomous microfluidic device was designed for the control of liquid operation based on centrifugal hydrokinetics (CLOCK) paradigm. The reported device was highly stable with less than 7% variation in the time of each unit operation (sample extraction, mixing, and supernatant extraction) with respect to the preparation process. Mixing of the sample and organic solvent in this device was realized using an agitation mechanism with bubbling. We confirmed that the device effectively removed protein aggregates from the sample, and the performance was comparable to that of conventional manual sample preparation procedure that uses high-speed centrifuge. In addition, probe electrospray ionization mass spectrometry (PESI-MS) was performed to compare the device-treated and manually treated samples. The obtained PESI-MS spectra were analyzed by partial least squares discriminant analysis, confirming that the preparation capability of the device was equivalent to that of the conventional method.