DETERMINATION OF SULFONATED AZO DYES BY LIQUID-CHROMATOGRAPHY ATMOSPHERIC-PRESSURE IONIZATION MASS-SPECTROMETRY

Sulfonated azo dyes are separated by high-performance liquid chromatography and introduced into the atmospheric pressure ion source of a triple quadrupole mass spectrometer using pneumatic nebulizers. A heated nebulizer together with a corona discharge produces ions by gas phase chemical ionization. Two related nebulizers operating at room temperature and floating at a high voltage make use of ions present in the liquid phase. Collision induced dissociation of left bracket M-H right bracket ** minus ions shows SO//3** degree ** minus as a fragment characteristic of sulfonated a dyes and parent ion scans on SO//3** degree ** minus are used for identification of azo dyes in environmental samples.