# Ambient-Pressure Multischeme Chemical Ionization for Pesticide Detection: A MION-Orbitrap Mass Spectrometry Study

## TL;DR

This study shows how using multiple ionization methods with MION-Orbitrap mass spectrometry improves pesticide detection from complex samples.

## Contribution

The study introduces a versatile MION-MS method that enables pesticide detection across a wide range of compounds using multiple ionization schemes.

## Key findings

- The method detected 136 compounds at 10 ng/mL and 447 at 100 ng/mL from standard pesticide solutions.
- Analysis of fruit extracts showed comparable results to validated methods.
- Molecular modeling explained the energetically favored fragmentation pathway using protonated acetone as a reagent ion.

## Abstract

This study explores
pesticide detection with diverse
ionization
reagents by employing Multischeme chemical IONization inlet (MION)
in conjunction with high-resolution Orbitrap mass spectrometry (MS).
Various ionization schemes, specifically charging by Br– and O2
– in negative polarity, and by
H3O+ and C3H6OH+ in positive polarity, were investigated. The findings build on our
previous work concerning pesticide detection using multischeme ionization
and further demonstrate the effectiveness of the MION-MS methodology
for detecting pesticides from complex standard mixtures and fruit
extracts. The method successfully detected 136 compounds at a concentration
of 10 ng/mL, and 447 at a concentration of 100 ng/mL, from standard
solutions containing altogether 651 pesticides. The analysis of 10
fruit extracts revealed detections comparable to those obtained with
validated methods. Subsequent molecular modeling provided insight
into product identities observed when using protonated acetone as
a reagent ion, which revealed that fragmentation into protonated pesticide
and neutral acetone is energetically favored over decomposition to
pesticide and protonated acetone (reactants). The current study amply
underscores the versatility of the MION-MS methodology in seamlessly
transitioning between different reagent ions in both polarities, enabling
detection of a wider range of chemical compounds than with any single-ion-scheme
instrument.