Rapid detection of pesticides not amenable to multi-residue methods by flow injection–tandem mass spectrometry

Abstract

Flow injection combined with tandem mass spectrometry (MS/MS) was investigated for the rapid detection of highly polar pesticides that are not amenable to multi-residue methods because they do not partition into organic solvents and require dedicated chromatographic conditions. The pesticides included in this study were amitrole, chlormequat, cyromazine, daminozide, diquat, ethephon, fosetyl-Al, glufosinate, glyphosate and its metabolite aminomethylphosphonic acid, maleic hydrazide, mepiquat and paraquat. The composition of the flow-injection solvent was optimized to achieve maximum MS/MS sensitivity. Instrumental limits of detection varied between <0.05 and 1 pg. Fruit, vegetable, cereal, milk and kidney samples were extracted with water (1% formic acid in case of paraquat/diquat) and ten times diluted in either methanol/0.1% formic acid, methanol/0.1% ammonia or acetonitrile/0.1% ammonia, depending on the pesticide. The ion suppression observed depended strongly on both the matrix and the pesticide. This could be largely compensated for by matrix-matched calibration, but more accurate quantification was obtained by using isotopically labelled standards (commercially available for most of the pesticides studied). The method detection limits ranged from 0.02 mg/kg for chlormequat and mepiquat to 2 mg/kg for maleic hydrazide and were 0.05-0.2 mg/kg for most other pesticide/matrix combinations. This was sufficiently low to test compliance with EU maximum residue limits for many relevant pesticide/commodity combinations. The method substantially reduces the liquid chromatography-MS/MS capacity demand which for many laboratories is prohibitive for inclusion of these pesticides in their monitoring and surveillance programmes.

Rapid Quantitative Analysis of Multiple Explosive Compound Classes on a Single Instrument via Flow‐Injection Analysis Tandem Mass Spectrometry

“…According to Mol et al, () the sensitivity of the FIA method is strongly dependent on the analyte's peak shape, which in turn depends on the capillary internal diameter, length, and the flow rate of the solvent. In this work, the highest sensitivity was achieved with the 0.13 mm internal diameter capillary of ~1 m length between the autosampler and the ionization source of the mass spectrometer, flow solvent delivery rate was set at 350 μL/min.…”

Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry Analysis of Fosetyl-Aluminum in Airborne Particulate Matter

“…As for LOD, other authors found, in food matrices [ 18 ], comparable values (0.2 mg·kg −1 ) of fosetyl. In air particulate matter (PM 2.5 ), Coscollà et al [ 19 ] found, for other pesticides by LC-MS/MS, LOQ values with the same order of magnitude (pg·m −3 ).…”

Determination of fatty acid methyl esters in cosmetic castor oils by flow injection–electrospray ionization–high‐resolution mass spectrometry

“…The following parameters were considered: (i) sample loop volume, (ii) composition of carrier solution, (iii) flow rate and (iv) sampling frequency. As recommended elsewhere , capillary PEEK tubing with internal diameter of 0.005″ was applied for connecting a Rheodyne injection valve with the ESI and the shortest possible distance was set (9 cm). The sample loop was made from this same tube, 2 μL volume was sufficient for the acquisition of mass spectrum and for signal integration, and provided the fit‐for‐purpose sensitivity.…”