Abstract by Jiuzhi Gao
Chemistry and Biochemistry
Peak Amplitude vs. Peak Area: which better measures charge in CDMS?
Charge detection mass spectrometry (CDMS) is an important technique that measures charge and m/z independently for each sample particles with virtually no upper mass limit. Both peak amplitudes and peak areas of the Gaussian differentiated signals have been suggested for determining the charge of sample particles. In most situations, peak amplitudes are chosen for simplicity. We designed a PCB image-charge detector patterned with two isosceles right triangular sensing electrodes. Each charged polystyrene bead will enter the first detecting triangle across the hypotenuse with a smaller velocity component and leave across a side leg with a larger velocity component. This sequence reversed at the second triangular electrode. By manipulating the entering and leaving angle and therefore velocity component perpendicular to electrode edge, we observed a clear trend that the peak amplitudes are negatively correlated with particles’ incident angle while positively correlated with the velocity component. Results show that signal amplitudes are largely influenced by the approaching velocity and incident angle while peak area better measures its charge.