Determination of glyphosate and AMPA in oat products for the selection of candidate reference materials

The use of reference materials (RMs) is critical for validating and testing the accuracy of analytical protocols. The National Institute of Standards and Technology (NIST) is in initial stages of developing a glyphosate in oats RM. The first aim of this study was to optimize and validate a robust method for the extraction and analysis of glyphosate and aminomethylphosphonic acid (AMPA). The optimized method was used to screen thirteen commercially available oat products to identify candidate RMs. Glyphosate was detected in all samples, with the highest glyphosate mass fraction of 1100 ng/g; lower levels were measured in grains from organic agriculture. AMPA was quantified in nine samples up to 40 ng/g. The findings of this study led to the identification of candidate RMs, with "high" and "low" glyphosate levels. A preliminary stability study determined that glyphosate is stable in oat material at room temperature for six months.