A Derivatization-Based Charge Localization Strategy for Suppressing in-Source Dehydration in LC-ESI(+)-MS Analysis of...

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Organic Chemistry

Background:

• Electrospray ionization (ESI) often yields multiple precursor ions for analytes with multiple hydroxyl or ether groups, complicating analysis.
• Okadaic acids (OAs) show significant sodium/potassium adduction and dehydration under ESI, unlike azaspiracids which form stable protonated ions.

Purpose of the Study:

• To address ion dispersion issues in OA analysis by ESI.
• To improve sensitivity and simplify precursor ion selection in mass spectrometry.

Main Methods:

• Chemical derivatization of OAs using IPPAH to introduce a charge-localizing group.
• Electrospray ionization in positive ion mode (ESI(+)) analysis of native and derivatized OAs.

Main Results:

• OAs derivatized with IPPAH showed high precursor-ion convergence in ESI(+), with up to 95% as a single [M + H]+ ion.
• Peak intensities for derivatized OAs increased by 2.6-4.7 fold compared to native OAs.
• The derivatization suppressed in-source dehydration and metal adduct formation.

Conclusions:

• Chemical control of charge localization is effective in suppressing ion dispersion during ESI.
• IPPAH derivatization offers a viable strategy to enhance ESI performance for OAs and similar compounds.
• This approach improves sensitivity and simplifies mass spectrometry-based analysis of complex molecules.