Abstract
Fosetyl-aluminum is a widely used ionic fungicide. This pesticide is not amenable to the common multi-residue sample preparation methods. Herein, this paper describes a novel method for the simple and sensitive determination of fosetyl-aluminum residue in wheat flour. The sample preparation method involved extraction with water under ultrasonication and subsequent dilution with six-fold acetonitrile. The fosetyl-aluminum concentration was determined by hydrophilic interaction liquid chromatography tandem mass spectrometry. The limit of detection and quantification were only 5 and 10 ng/g, respectively, which meet the requirement of the current European legislation. Matrix-matched linearity (r2 = 0.9999) was established in the range of 10–2000 ng/g. Satisfactory recoveries were achieved in the range of 95.6% to 105.2% for three levels of spiked samples (10, 50, and 100 ng/g). Finally, the method was applied to analyzing 75 wheat flour samples produced in four provinces in China. Two samples were positive with concentrations over the limit of detection. This is the first method focusing on fosetyl-aluminum determination in wheat flour with an extract-dilute-shoot strategy and is very promising for the routine quality control of fosetyl-aluminum in similar cereal matrices.
Highlights
Fosetyl-aluminum is a polar fungicide, and a replacement for the banned sodium arsenite [1]
Fosetyl-Al is a highly polar compound with an ionic structure. This highly polar pesticide is not amenable to the common multi-residue sample preparation methods because it is difficult to partition into common organic solvents [6] and needs dedicated chromatographic conditions
In these liquid chromatography mass spectrometry (LC-MS) methods, polar pesticides are separated with graphitized carbon (Hypercarb) columns [13] or hydrophilic interaction liquid chromatography (HILIC) columns [9,14,15]
Summary
Fosetyl-aluminum (fosetyl-Al) is a polar fungicide, and a replacement for the banned sodium arsenite [1]. Several recent works have described the use of LC-MS for fosetyl-Al determination in different food commodities, such as lettuce [7], tomato [9], grape [1], mango [10], olive oil [11], oat, and soy beans [12] In these LC-MS methods, polar pesticides are separated with graphitized carbon (Hypercarb) columns [13] or hydrophilic interaction liquid chromatography (HILIC) columns [9,14,15]. To the best of our knowledge, this is the first report that focuses on fosetyl-Al determination in wheat flour with extract-dilute-shoot sample preparation and HILIC-MS/MS determination
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