Enhanced analysis of sulfonated azo dyes using liquid chromatography/thermospray mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Chromatography

Background:

• Thermospray ionization is a common technique for introducing liquid samples into mass spectrometers.
• Optimizing thermospray ionization is crucial for enhancing sensitivity and enabling the detection of trace analytes.
• Sulfonated azo dyes are widely used in various industries and require sensitive analytical methods for their detection and quantification.

Purpose of the Study:

• To improve the performance of thermospray vaporizer probes and ion sources for enhanced ion evaporation.
• To investigate the effects of specific modifications on the detection of sulfonated azo dyes.
• To develop an efficient chromatographic separation method compatible with thermospray mass spectrometric detection.

Main Methods:

• Modifications to the thermospray vaporizer exit orifice to restrict flow.
• Addition of a needle-tip repeller electrode to the thermospray ion source.
• Optimization of probe-tip size, repeller voltage, and flow rate.
• Development of a chromatographic separation procedure for sulfonated azo dyes.
• Analysis using selected ion monitoring (SIM) with thermospray mass spectrometry.

Main Results:

• Increased sample ion current due to enhanced ion evaporation.
• Significant increase in signal response for sulfonated azo dye detection.
• Successful separation and detection of five disulfonated azo dyes.
• Obtained mass spectra provided unequivocal molecular weight information through molecular ions and adduct ions.

Conclusions:

• The implemented modifications effectively enhance ion evaporation and signal response for sulfonated azo dyes.
• The developed chromatographic method is efficient and compatible with thermospray mass spectrometry.
• The study demonstrates a robust approach for the sensitive detection and characterization of sulfonated azo dyes.