I. Pereira, B. Banstola, K. Wang, F. Donnarumma, B.G. Vaz, K.K. Murray, Matrix-Assisted Laser Desorption Ionization Imaging and Laser Ablation Sampling for Analysis of Fungicide Distribution in Apples, Anal. Chem. 91 (2019) 6051–6056. 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.