MALDI pigments

Fig. 10.8. Comparison of spectra of the organic dye pigment red 144 as obtained by (a) LDI, (b) solvent-based and (c) solvent-free MALDI sample preparation. Adapted from Ref. [109] by permission. John WUey Sons, 2001. 

Figure 5-5. A. MALDI mass spectrum of the anthocyanin pigments in the grape variety Marechal Foch. This figure is from the article Matrix-assisted laser desorption ionization mass spectrometry analysis of grape anthocyanins , Am. J. Enol. Vitic. 50 199-203 by Sugui, J. A., Wood, K. V., Yang, Z., Bonham, C. C. and Nicholson, R. L. 1999. Reprinted by permission of the American Society for Enology and Viticulture. B. MALDI mass spectrum of grape anthocyanins acquired on a MALDI mass spectrometer with delayed extraction capabilities. Peak identities are discussed in the text.

Spatially resolved MS techniques that make use of ionic sources based on direct LDI have been employed to study art and archaeological objects since 2002 [43,44]. However, direct LDI is only effective in the study of a limited range of materials. TTie use of matrices that assist the ionization process induced by MALDI has expanded the applicability of LDI-based MS methods to the field of spatially resolved studies of organic components from works of art. Examples of the applicability of MALDI to the analysis of pigments [45], siccative oils [46], proteinaceous binders [47-49], and varnishes [50] are indeed reported in the literature. A proteomic approach based on the use of MALDI-TOF was also used to identify biological samples taken from the more than 5300-year-old Tyrolean mummy, also called iceman or Oetzi [51]. 

The third and the only other online TLC-MS approach in carotenoid analysis was presented in the study of the introduction of TiOj nanoparticles on increase of carotenoid production by the extremophilic haloarchea Haloferax mediterranei [7]. The carotenoids were extracted from bacteria and chromatographed on silica gel TLC plates developed by acetone-n-heptane (1 1, v/v). To prevent the diffusion of bands on the developed silica gel TLC plate, the area surrounding the bands was carefully scraped off prior to the addition of MALDI matrix. Based on the high-resolution mass spectra, the four colored pigments were identified as bisanhydrobac-terioruberin, monoanhydrobacterioruberin, 2-isopentenyl-3,4-dehydrorhodopin, and... 

Stafsnes MH, Dybwad M, Brunsvik A, Bruheim P. Large scale MALDI-TOF MS based taxa identification to identify novel pigment producers in a marine bacterial culture collection. Antonie Van Leeuwenhoek. 2013 103(3) 603-15. doi 10.1007/sl0482-012-9844-6. 

There have been considerable advances in mass spectrometry in the last 10 years. Advanced techniques such as matrix-assisted laser desorption ionization (MALDI), electrospray ionization (ESI), thermospray ionization, plasma desorption, and ion spray have been improved and are widely used to obtain the mass spectra of polar and nonpolar compounds with the mass of several thousand Daltons. New MS-MS techniques can provide structural information based on fragmentation of selected ions and are of great value both for qualitative and quantitative analyses especially in difficult matrices. There is no method of ionization that is ideal for all samples. Often the analyst and pigment chemist must work togeth-... 

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