In this work, paper spray (PS) is combined with atmospheric pressure photoionization-mass spectrometry (PS-APPI-MS) for the determination of non-polar and low polar compounds, such as the neutral per- and polyfluorinated alkyl substances (PFAS). The proposed PS-APPI-MS method has been developed for the analysis of fluorotelomer alcohols (FTOHs), fluoroctanesulfonamides (FOSAs) and fluorooctane sulfonamido-ethanols (FOSEs), using both negative ion mode and high-resolution mass spectrometry (HRMS). The most critical working parameters (i.e., UV-krypton lamp position, sample drying time, spray dopant solvent and spray voltage) have been evaluated to study both the ionization behaviour and ionization efficiency. The best results were achieved using dopant-assisted PS-APPI-HRMS with toluene as dopant solvent. The most intense ions observed in the mass spectra, [M‒H]‒ for FOSAs and [M+O2]‒• for FTOHs and FOSEs, were selected and proposed for fast screening and quantitative analysis of target compounds in waterproof impregnation sprays samples using internal standard calibration method and being able to detect down to μg L-1 levels. The satisfactory values of the method quality parameters (detection capability, repeatability, trueness and linearity) demonstrated the good performance of the PS-APPI-HRMS method and allowed the identification and quantitation of some FTOHs (6:2 FTOH, 7-Me-6:2 FTOH, 8:2 FTOH, 10:2 FTOH) and N-MeFOSE at mg L-1 in some of the waterproof impregnation spray products analyzed. This low-cost PS-APPI-HRMS method allows a fast screening, with minimum sample preparation, of non-polar and low polar compounds simultaneously, which can significantly improve the throughput on routine laboratories.

Modern food laboratories are demanding fast screening methods to display a wide range of compounds present at low concentration levels in a large number of complex food samples. For these laboratories, sample treatment and chromatographic separations are often their bottlenecks. The development of ambient ionization mass spectrometry (AIMS) techniques may overcome some of these difficulties, as they allow a rapid, real-time, high-throughput, and in situ analysis of solids, liquids, and gases without the need of rigorous sample treatments. Since the development of the two first AIMS techniques (desorption electrospray ionization and direct analysis in real time), a large number of new ambient ionization strategies have emerged, and nowadays, there are a wide of AIMS techniques available that relay on combining in situ sample processing with different ionization mechanisms. This chapter highlights and assesses the application of AIMS techniques for the analysis of food samples. The fundamentals of AIMS techniques most commonly used for the direct analysis of food are included, and the critical aspects of each technique are commented on. Capabilities and the applicability of these techniques for the rapid screening of both target and nontarget compounds in the food field, as well as new approaches for the on-site analysis, are also discussed.

Benzophenone and its derivatives (BPs) are commonly used as photoinitiators in UV-inks and as additives in plastic food packaging.

In this work, we tested the potential of desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) for the analysis of unknown materials. To this end, our study focused on analyzing an unknown complex sample suspected of being an adulterated phytosanitary product or a fraud. A simple and fast sample manipulation procedure (filter paper impregnated with the sample) was used for the chemical characterization of the phytosanitary product by DESI-HRMS(/MS). Kendrick Mass Defect (KMD) analysis was used to process the DESI high-resolution mass spectral data, allowing the identification of a low molecular weight polymer (polyethylene glycol) and the detection of other ions, which did not follow polymer distributions. The characteristic isotope patterns of these ions suggested the presence of organometallic compounds. Accurate mass measurements, isotope pattern fits and the structural information obtained by DESI-MS/HRMS (wide isolation window) allowed identifying the presence of triphenyltin, a biocide extensively used for agricultural purposes and restricted by the European Commission, in the phytosanitary product. The concentration of triphenyltin in the sample was 35%, which corresponds to ∼12% expressed as weight of tin, 120 times higher than the maximum legislated level.