Novel co-matrix systems for the MALDI-MS analysis of polystyrene using a UV absorber and stabilizer

Co-matrix systems composed of a UV absorber and a UV stabilizer applied to the analysis of polystyrene (PS) using a matrix-assisted laser desorption/ionization-mass spectrometer (MALDI-MS) equipped with a N2 laser (337 nm) as the light source were investigated. Various UV absorbers such as Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, and Tinuvin 1577 and a UV stabilizer of Tinuvin 770 were used. Analytical results using the co-matrix systems were compared with those using anthracene-1,8,9-triol (DIT) as the most common matrix for PS analysis. The MALDI mass spectrum of PS obtained using single DIT showed higher ionization efficiency than that using a mixture of DIT and Tinuvin 770 as the matrix. In contrast to this, for the UV absorbers, the ionization efficiencies were notably enhanced by using the co-matrix systems of the UV absorber and Tinuvin 770. The analytical results were explained with the enhanced compatibility with PS by the formation of a complex between the UV absorber and Tinuvin 770 and with the capability of transferring silver cations. Prices of Tinuvin 770 and the UV absorbers are much cheaper than those of the common matrices. The co-matrix systems are recommendable for the MALDI-MS analysis of PS, especially the co-matrix system composed of Tinuvin 234 and Tinuvin 770.