Automated Control of Injection Times for Unattended Acquisition of Multiplexed Individual Ion Mass Spectra.

Charge detection mass spectrometry (CDMS) provides mass domain spectra of large and highly heterogeneous analytes. Over the past few years, we have multiplexed CDMS on Orbitrap instruments, an approach termed Individual Ion Mass Spectrometry (I 2 MS). Until now, I 2 MS required manual adjustment of injection times to collect spectra in the individual ion regime. To increase sample adaptability, enable online separations, and reduce the barrier for entry, we report an automated method for adjusting ion injection times in I 2 MS for image current detectors like the Orbitrap. Automatic Ion Control (AIC) utilizes the density of signals in the m / z domain to adjust an ensemble of ions down to the individual ion regime in real-time. The AIC technique was applied to both denatured and native proteins yielding high quality data without human intervention directly in the mass domain.