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End group analysis of poly (methylmethacrylate)s using the most abundant peak in electrospray ionization-ion mobility spectrometry-tandem mass spectrometry and Fourier transform-based noise filtering.

RATIONALE
We recently developed the characterization method for synthetic polymers weighting over a few tens kDa in electrospray ionization-ion mobility spectrometry-tandem mass spectrometry, in which the m/z value of most abundant peak was used for the characterization. However, the identification of the most abundant peak from the isotopic peaks was often difficult due to the background noise.


METHODS
Here, we employed a noise-reduction method using Fourier transform (FT) filtering. In the power spectrum obtained by FT of the mass spectrum of the multiple charged analytes, the significant signals in low-frequency region and at frequency z are observed for the analytes of z charges. When the signals in both regions were used for inversed FT (that is, the signal other regions were zero padded), a noise filtered mass spectrum is obtained.


RESULTS
In analysis of poly (methylmethacrylate)s weighing 13-17 kDa, mass spectra without noise filtering with relatively high intensity noise (than signal) was complicated to identify the most abundant peak. On the other hand, the most abundant peak was clearly identified from the mass spectra after FT-based noise filtering, and estimation of end group composition was successfully achieved.


CONCLUSIONS
The proposed FT-based noise filtering for the mass spectrum is the effective to characterize multiply charged synthetic polymers weighting over a few tens kDa in electrospray ionization-ion mobility spectrometry-tandem mass spectrometry.