Effects of ion-pairing reagents on the electrospray signal suppression of sulphonated dyes and intermediates.
High-performance liquid chromatography/mass spectrometry (HPLC/MS) analysis of anionic species such as sulphonic acid dyes and intermediates requires volatile ion-pairing mobile phase additives. Six di- and trialkylammonium acetates were compared with tetraalkylammonium salts and ammonium acetate in the concentration range 0-20 mmol l(-1) as mobile phase additives for HPLC/MS of polysulphonated compounds. The effects of the structure and concentration of the ion-pairing reagents on the electrospray response of mono-, di- and tetrasulphonic aromatic acids and acid dyes were studied in detail. Further, five different mass analysers and instrument geometries were compared. A higher signal decrease is observed with linear geometry instruments in comparison to orthogonal or even Z-spray geometry mass spectrometers. The concentration of mobile phase additives has a significant influence on the abundance ratios of multiply charged ions in the mass spectra of polysulphonated compounds. The competing ions of sulphonic acids may also cause significant signal suppression.
Holcapek
M
M
Faculty of Chemical Technology, Department of Analytical Chemistry, University of Pardubice, nám. Cs. legií 565, 53210 Pardubice, Czech Republic. Michal.Holcapek@upce.cz
Volná
K
K
Jandera
P
P
Kolárová
L
L
Lemr
K
K
Exner
M
M
Církva
A
A