Matrix-Assisted Laser Desorption Ionization Imaging and Laser Ablation Sampling for Analysis of Fungicide Distribution in Apples

  • Anal Chem. 2019 May 7;91(9):6051-6056. doi: 10.1021/acs.analchem.9b00566.
Igor Pereira  1  2 ,  Bijay Banstola  1 ,  Kelin Wang  1 ,  Fabrizio Donnarumma  1 ,  Boniek G Vaz  2 ,  Kermit K Murray  1
Affiliations
  • 1. Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States.
  • 2. Chemistry Institute , Federal University of Goiás , Goiânia , Goiás , 74690-900 , Brazil.
PMID: 30969757 DOI: 10.1021/acs.analchem.9b00566
Abstract

A combination of matrix-assisted laser desorption ionization (MALDI) imaging and infrared (IR) laser ablation sampling with offline electrospray ionization mass spectrometry (ESI-MS) was used to determine the distribution of the fungicide imazalil in apples. MALDI images were used to determine the penetration depth of imazalil up to 7 days after its application. IR laser ablation sampling and ESI-MS were used to quantify the rate of penetration of the fungicide, which was determined to be approximately 1 mm per day. Imazalil concentration decreased in the apple skin over the course of the experiment, and after 7 days the fungicide was detected at 0.015 ppm 6 mm inside the apple. Approximately 60% of the pesticide remained in the skin after 7 days. This work demonstrates the utility of MALDI imaging for spatial localization of fungicide in fruit in combination with IR laser ablation and ESI-MS for quantitative analysis.

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