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A comparison of EDI with solvent‐free MALDI and LDI for the analysis of organic pigments
Author(s) -
Kudaka Ichiro,
Asakawa Daiki,
Mori Kunihiko,
Hiraoka Kenzo
Publication year - 2008
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1271
Subject(s) - chemistry , pigment , desorption , mass spectrometry , solvent , chromatography , analytical chemistry (journal) , sample preparation , substrate (aquarium) , ion , ionization , mass spectrum , matrix (chemical analysis) , organic chemistry , adsorption , oceanography , geology
To evaluate the applicability of EDI to material analysis as a new ionization method, a comparison of EDI with solvent‐free matrix‐assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) was made for the analysis of organic pigments, e.g. Pigment Yellow 93, Pigment Yellow 180, and Pigment Green 36, as test samples, which are poorly soluble in standard solvents. In EDI, the samples were prepared in two ways: deposition of suspended samples in appropriate solvents and dried on the substrate, and the direct deposition of the powder samples on the substrate. No matrices were used. Both sample preparation methods gave similar mass spectra. Equally strong signals of [M + H] + and [M − H] − ions were observed with some fragment ions for azo pigments in the respective positive or negative mode of operation. For the powder sample of the phthalocyanine pigment PG36, M +• and [M + H] + in the positive mode and M −• in the negative mode of operation were observed as major ions. Positive‐mode, solvent‐free MALDI gave M + , [M + H] + and [M + Na] + and negative mode gave [M − H] − depending on the sample preparation. As solvent‐free MALDI, EDI was also found to be an easy‐to‐operate, versatile method for the samples as received. Copyright © 2008 John Wiley & Sons, Ltd.