Impact of injection solvent composition on 90 pesticides by LC-MS/MS: A data-driven framework for initial method...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Forensic Science

Background:

• Injection solvent composition is a critical, yet often overlooked, factor in LC-MS/MS.
• Accurate pesticide quantification relies on understanding solvent effects on chromatography and ionization.

Purpose of the Study:

• To systematically evaluate the influence of injection solvent composition on pesticide analysis using LC-MS/MS.
• To determine optimal injection solvent ratios for diverse pesticide polarities.

Main Methods:

• Analysis of 90 pesticides using solvent-based standards in LC-MS/MS.
• Comparison of acetonitrile/water and acetonitrile/buffered mobile phase mixtures at various ratios (10/90 to 50/50 v/v).
• Focus on chromatographic and ionization effects, excluding matrix effects.

Main Results:

• Polar pesticides showed enhanced signals (up to 14-fold) in highly aqueous solvents due to on-column focusing.
• Non-polar pesticides required higher organic content for optimal solubility and response.
• A 30/70 acetonitrile/aqueous ratio proved effective for mid-polarity compounds.
• ANOVA confirmed significant impact of solvent ratio on MS response (p < 0.001).

Conclusions:

• Injection solvent selection is crucial for enhancing sensitivity and chromatographic integrity in pesticide LC-MS/MS.
• Guidelines are provided for optimizing injection solvents during method development.
• This foundational study aids in improving multi-residue pesticide analysis accuracy.