Role of a UV Absorber as a Matrix for Analysis of Polystyrene Using Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry

Abstract

Matrix-assisted laser desorption/ionization (MALDI) has been widely used as a soft ionization technique and matrixassisted laser desorption/ionization-mass spectrometry (MALDI-MS) has been used to characterize polymeric materials.1-5 MALDI is achieved in two steps. [6][7][8][9] In the first step, a mixture solution of an analyte and a matrix is spotted on the sample plate, and is dried before analysis. A solid solution deposit of analyte-doped matrix crystals is obtained, and the analyte molecules are completely isolated from each other by embedding throughout the matrix. The second step involves ablation of the solid solution by pulse laser. The pulse laser irradiation induces rapid heating to cause sublimation of the matrix crystals and ionization can occur during this process. Selection of the matrix in MALDI-MS absolutely affect the MALDI process. 1,2o-Hydroxyphenyl benzotriazole and hydroxyphenyl triazine derivatives are commonly used as UV absorbers. They absorb destructive UV radiation and dissipate the energy in the form of heat.9-15 In general, the UV absorbers absorb UV wavelength between 295 and 400 nm, so they can potentially play a role as a matrix in MALDI analysis. 16,17 In this study, the UV absorbers were employed as the matrix to analyze polystyrene (PS) using MALDI-MS. The UV absorbers absorb UV radiation well, are not expensive, and are easily available materials. The analytical results using the UV absorbers were compared with that using anthracene-1,8,9-triol (DIT). DIT is the most common matrix for MALDI-MS analysis of PS. 1,18,19Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, Tinuvin 360, and Tinuvin P are UV absorbers of o-hydroxyphenyl benzotriazole derivatives. Tinuvin 1577 is a UV absorber of a hydroxyphenyl triazine derivative. Figure 1 shows the MALDI-MS spectra of PS obtained from the samples prepared using DIT and Tinuvin 234 as the matrix. Abundances of the [PS + Ag] + ions of the MALDI mass spectrum obtained using Tinuvin 234 were larger than those obtained using DIT by about twice. It is a very interesting result because DIT is known to be a proper matrix for MALDI-MS analysis of PS. The average molecular weights were about 4,000-4,200 as listed in Table 1. The average molecular weights for the Tinuvin 234 case were slightly larger than those for the DIT one by about 4%. The other UV absorbers of Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, Tinuvin 360, Tinuvin P, and Tinuvin 1577 were also employed as the matrix, and the analysis results are

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

“…The ionization efficiency of PS in MALDI-MS analysis using Tinuvin 234 as the single matrix was higher than that using DIT. 25 For the UV absorbers, the maximum peak intensity order is consistent with not only the numbers of the phenyl rings including benzotriazole but also with the length of the alkyl groups. The order of the number of the phenyl rings was Tinuvin 234 (4) > Tinuvin 1577 (3) > Tinuvin 329 (2), Tinuvin 328 (2), Tinuvin 327 (2), Tinuvin 326 (2).…”

“…In the previous work, UV absorbers were employed as the matrix for the MALDI-MS analysis of PS. 25 The novel comatrix systems composed of UV absorbers and a UV stabilizer can open access to a new class of matrices. Each PS, the matrix, and AgTFA was dissolved in THF to make a 10 mM solution.…”

Evaluation of UV-permeability and photo-oxidisability of organic ultraviolet radiation-absorbing coatings

“…Therefore, they may not be the most suited materials to form clear UV radiation-resistant coatings [13,14]. It is also known that organic compounds such as benzotriazoles (BTZs), triazines, malonates, and oxalanilides also absorb UV radiation [15][16][17][18][19][20][21]. There have been a few comparative studies on the photostabilities of coatings to which BTZ and micronized TiO 2 have been added.…”