According to the European Commission directive 2006/141/EC, haloxyfop residue levels should not exceed 0.003 mg/kg in ready-to-feed infant formula. Haloxyfop is a selective herbicide that is used to protect crops such as potatoes and carrots against persistent grasses. In a recent paper authored by Urairat Koesukwiwat et al., (Analytical and Bioanalytical Chemistry https://doi.org/10.1007/s0021), the authors developed and validated a simple method for total haloxyfop analysis in infant formula and related ingredient matrices using UCT’s QuEChERS and liquid chromatography-tandem mass spectrometry (LC-MS/MS).
The sample preparation consisted of an alkaline hydrolysis with methanolic sodium hydroxide to release haloxyfop (parent acid) from its conjugated forms prior to the QuEChERS extraction. Unbuffered salts containing magnesium sulfate (MgSO4) and sodium chloride (NaCl) (4:1, w/w) were used prior to dispersive solid phase extraction (dSPE). A 1-mL aliquot was cleaned up with a 2mL dSPE tube containing 150 mg of MgSO4 and 50 mg of octadecyl (C18) sorbent from UCT.
The analytical procedure was developed and carefully optimized to enable low-level, total haloxyfop analysis in a variety of challenging matrices, including infant formulas and their important high-carbohydrate, high-protein, high-fat, and emulsifier ingredients. The final method was validated in two different laboratories by fortifying samples with haloxyfop and haloxyfop-methyl, which was used as a model compound simulating bound forms of the analyte.
Mean recoveries of haloxyfop across all fortification levels and evaluated matrices ranged between 92.2 and 114% with repeatability, within-lab reproducibility, and reproducibility RSDs ≤ 14%. Based on the validation results, this method was capable to convert the haloxyfop ester into the parent acid in a wide range of sample types and to reliably identify and quantify total haloxyfop at the target 0.003 mg/kg level in both powder and liquid infant formulas.
UCT QuEChERS and dSPE sorbents are an excellent choice for analysis of residual herbicides in food-based matrices. For more information regarding this product line, please visit our QuEChERS homepage.