Hi, I have been working with data from LC/MS electron spray mass spectrometer. I have found the ts structure works very well for dealing with the raw spectra, but have written my own structures to extend ts for multiple spectra. The filters in genefilter work only if you have clean spectra. If you are trying to smooth, deconvolve, and identify peaks not everything is there in R already. I think there could be some fun work here putting together a package that has more signal processing functionality. I have written some simple svatsky-golay, and kalman filter routines for my spectra classes. With some cleaning and massaging they could be a start for a package to process MS data. Of course some more sophisticated filters would be needed such as fir and and iir as well as some wavelet methods. Nicholas