Perfluoroalkyl Group-Covered Organosilica Films for the Sensitive Detection of Sulfonylurea Herbicides in Laser Desorption/Ionization Mass Spectrometry.

Simple and rapid screening of agrochemicals greatly contributes to food and environmental safety. Matrix-free laser desorption/ionization mass spectrometry (LDI-MS) is an effective tool for high-throughput analysis of low-molecular-weight compounds. In this study, we report a UV-laser-absorbing organosilica film for the sensitive detection of various sulfonylurea herbicides using LDI-MS. Organosilica films with fluoroalkyl groups on the organic part are fabricated, followed by additional modification of the silica moiety with a fluoroalkyl coupling agent to cover the film surface with hydrophobic fluoroalkyl groups. Nanoimprinting is conducted to impart nanostructures on the film surface to enhance the LDI performance. The fabricated nanostructured organosilica films accomplish sensitive detection of cyclosulfamuron and azimsulfuron at concentrations as low as 1 fmol μL. The applicability of the nanostructured organosilica films is confirmed by the recovery of cyclosulfamuron and ethametsulfuron-methyl from pea sprouts () hydroponically grown in herbicide-spiked water at concentrations of 0.5 ppm.