Improvement of Wine Quality: Tannin and Polymeric Pigment Chemistry
Our last update demonstrated the usefulness of MALDI-FTICR (Matrix Assisted Laser Desorption Ionization Fourier Transform Ion Cyclotron Resonance), the efficiency of QTOF (Quadrupole Time of Flight) tandem mass spectrometric analysis, and the successful fractionation of wine samples. Having demonstrated our methods adequate we set about tailoring them to our experimental needs and adapting our instrumentation and methodology. We have since discovered even better FTICR results with an electrospray ionization source (ESI), and created a method of analysis for pigmented tannin and wine polymers using nano-HPLC QTOF.
ESI-FTICR results have demonstrated resolution greater than 50,000 and tremendous mass accuracy with error less than 1ppm. The QTOF method was modeled originally on the diol stationary phase cocoa extract separation by Robbins (Kelm et al 2006). We have since made significant alterations so as to provide a nano-scale elution with total column volume around 50 μL. Unfortunately, nano columns comprised of diol stationary phases are not in production. We partnered with the manufacturer of our best performing traditional column as well as Agilent Technologies to fabricate a nano-LC chip made from Develosil Diol 100-5. The results we have obtained would not have been possible otherwise.
So far, we believe we have identified over one hundred ions by ESI-FTICR which have never before been published. With those same samples we refined our QTOF method to isolate and fragment those ions providing fragmentation data for structural identification. Unfortunately, the fundamental nature of the project requires that these ion fragmentation spectra be analyzed by hand for neutral mass loss functional assignments. The work is still ongoing. Soon we will have enough fragmentation spectra to verify their identities. We anticipate presentation of new compounds in time for the ASEV national conference 2014 in Austin, TX.