Single- and Multiple-Laboratory Validation of LC-MS/MS Method for Simultaneous Determination of Fosetyl-Al and Phosphonic Acid in Cereal Grains and Analysis of Rice, Wheat, and Barley

Abstract

Background and objective In Japan, the residue definition for fosetyl-Al was “sum of fosetyl-Al and phosphonic acid expressed as fosetyl-Al” and its current provisional MRL in cereals was under review. For establishment and enforcement of fosetyl-Al MRL in cereals, a new analytical method for fosetyl-Al and phosphonic acid in cereals should be developed and validated. Methods The new method involved water extraction, clean-up using tandem cation- and anion-exchange mini-columns, and determination by LC-MS/MS. It was validated in single laboratory and multiple laboratories. Using the method, 41 samples of rice, wheat and barley were analyzed. Results In the multiple-laboratory validation: repeatability and reproducibility for three concentrations of fosetyl-Al and phosphonic acid were in ranges of 4.8–20% and 5.9–34%; calculated sum of fosetyl-Al and phosphonic acid, expressed as fosetyl-Al, showed good recoveries; linearity was observed for fosetyl-Al and phosphonic acid in ranges of 0.005–0.4 and 0.025–2.0 mg/kg; and specificity was sufficient. The method was verified for rice matrices. In 41 samples, phosphonic acid was detected up to 0.2 mg/kg while fosetyl was not. Conclusion The method was successfully validated with high precision, accuracy, linearity, and specificity and capable of analyzing fosetyl-Al and phosphonic acid with the practical LOQ of 0.01 and 0.05 mg/kg. The LOQs and concentrations of phosphonic acid in samples indicate that a potential MRL would be 0.5 mg/kg for fosetyl-Al in cereals. Highlights The validated method was simpler than many methods and did not require derivatization or matrix matched or isotopically labeled internal standards.

Comparison of Ion Chromatography Conductivity Detection (IC-CD) and Ion Chromatography Inductively Coupled Plasma Mass Spectrometry (IC-ICP-MS) for the Determination of Phosphonic Acid in Grapevine Plant Parts, Wine, and Soil

“…By analogy to that from the liquid matrices, the recovery from solid samples ranged from 83.2 to 108.2% across all samples. The trace recovery of our IC-ICP-MS-based method was in accordance with the values reported by Adams et al, Bauer et al, and Sekiyama et al, who found recovery rates of 94–106, 80–106, and 88–96% of phosphonic acid in trace amounts of different food matrices (e.g., apple, lemon, avocado, wheat) after a single extraction, respectively. A slight overestimation was found for CD detection in sediment (107.3 or 108.2%) due to the high presence of tartrate precipitating in the must.…”

“…Further recent analytical approaches focused on liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods for the simultaneous determination of polar pesticides including phosphonate. − One pitfall of this method is that an important negative ion mass transition of phosphonic acid ( m / z 81 → 63) is also observed as a minor transition of phosphoric acid, which can lead to major interferences in case of insufficient chromatographic separation. To solve this problem, an alternative mass transition for phosphonic acid ( m / z 81 → 79) has been recommended, particularly because the chromatographic resolution between these related compounds is often poor in the presence of high amounts of phosphoric acid or its anion, as found in grapes and grapevines .…”

Analysis of highly polar pesticides in foods by LC-MS/MS

“…For SPE, the performance of different commercial SPE cartridges was evaluated. The result indicates that combining mixed-mode cation-exchange (MCX) and enhanced matrix removal (EMR) can give the best recovery and the lowest matrix effect of HPP residues in oats [ 14 , 23 , 24 ]. Another easy way to precipitate unwanted coextracts is by freezing the extracts [ 15 ].…”

“…This technique enables sample pretreatment and analysis to be completed at the same time. In addition, an ion exchange mini column can also be utilized as a sample clean-up method for quantifying fosetyl-Al and phosphonic acid in rice, wheat, and barley [ 23 ].…”

Determination of Polar Pesticides Based on a Modified QuPPe with Liquid Chromatography Coupled to Tandem Mass Spectrometry

“…In many countries, fosetyl and its aluminum salt (fosetyl-Al) are systemic fungicides used to control oomycetes and ascomycete fungi, as well as some plant pathogenic bacteria, in fruit trees, vegetables, and ornamental plants [10]. Glyphosate (N-phosphonomethyl glycine) is a nonselective postemergence herbicide used to control a wide variety of grass and broad-leaf-weed species in agricultural and industrial settings [11].…”