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Influence of experimental conditions on the liquid secondary ion mass spectra of sulfonated azo dyes
Author(s) -
Richardson Susan D.,
Thruston Alfred D.,
McGuire John M.,
Baughman George L.
Publication year - 1991
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210261004
Subject(s) - ion , mass spectrum , analytical chemistry (journal) , chemistry , mass spectrometry , matrix (chemical analysis) , ionization , secondary ion mass spectrometry , chromatography , organic chemistry
Two monosulfonated and eight disulfonated azo dyes of varying relative molecular mass were examined by liquid secondary ion mass spectrometry (LSIMS). The effects of matrix, concentration, primary beam energy, and mode of operation were addressed in order to optimize sample ionization, whilst minimizing interference from matrix ions. Seven matrices were investigated: glycerol, thioglycerol, 3‐nitrobenzyl alcohol, diethanolamine, 2‐hydroxyethyl disulfide, a 1:1 (v/v) mixture of 2‐hydroxyethyl disulfide and thioglycerol, and a 1 : 3 (v/v) mixture of dithioerythritol and dithiothreitol. Of these matrices, 3‐nitrobenzyl alcohol produced LSIMS spectra that exhibited the most intense sample ions and the least inteiference from matrix ions. Minimum concentrations of 0.4 μg/μl and 4 μg/μl (dye in matrix) were necessary to produce useful full‐scan spectra for monosulfonated azo dyes and disulfonated azo dyes, respectively; maximum sample ion intensities were obtained with concentrations ranging from 20 μg/μl to 60 μg/μl. A primary ion beam (cesium) of 10 to 15 kV produced the greatest secondary ionization efficiency, and a negative‐ion analysis mode produced more useful spectra than those obtained in the positive‐ion mode.