MODIFICATION OF A COMMERCIALLY AVAILABLE THERMOSPRAY INTERFACE AND ITS USE FOR THE ANALYSIS OF SULFONATED AZO DYES BY LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY

A standard commercial thermospray interface was modified by replacing the stainless-steel capillary by another stainless-steel capillary with a larger internal diameter. A fused-silica capillary was then placed within the whole length of the stainless-steel capillary and connected to the liquid chromatograph. A thermospray interface modified in this way exhibits a more inert inner surface, resulting in an increased sensitivity for analysing sulfonated azo dyes. Analysis of sub-microgram quantities is possible only with the modified interface.