An accurate and precise ultra‐high performance liquid chromatography with tandem mass spectrometry (UHPLC‐MS/MS) method was validated for the analysis of glyphosate and its main transformation product (aminomethylphosphonic acid) in barley, malt, wheat, oats, and lentils. The validation data demonstrated good performance of the method. This UHPLC‐MS/MS method was also used to evaluate the performance of a commercially available enzyme‐linked immunosorbent assay (ELISA) test kit. For all of the grain matrices examined, the ELISA showed poor accuracy and precision at its stated lower working limit of 0.075 mg/kg; however, performance was acceptable at 0.30 mg/kg, as well as higher concentrations relevant to established maximum residue limits. At these relevant concentrations, the ELISA also produced results higher than the UHPLC‐MS/MS method. Although results from the two methods were linearly correlated, differences in the result values from the two methods differed among the grains studied and ranged from +1% for oats to +40% for glyphosate concentrations in barley. ELISA is a useful tool that is complemented by the comprehensive and sensitive UHPLC‐MS/MS method.

By-products of cereal grain cleaning were analysed for a number of mycotoxins. Deoxynivalenol (DON) was the most frequently detected in by-products from commercial-scale cleaning procedures (maximum 2.94 mg/kg), followed by zearalenone (ZEA; maximum 0.045 mg/kg) and ochratoxin A (OTA; maximum 0.019 mg/kg). These three mycotoxins were also the most frequently detected in four different fractions collected from wheat run through a dockage tester, a piece of equipment used in the Canadian inspection process to separate material other than grain from wheat. Concentrations of mycotoxins were highest in the ‘light dockage’ fraction that contained dust and roughage such as glumes, fragments of stem, or rachis. Mycotoxin concentrations in this fraction reached up to 32 mg/kg (DON), 0.532 mg/kg (ZEA), and 0.249 mg/kg (OTA). Concentrations of DON in light dockage were significantly correlated with concentrations in whole grain that was un-cleaned or had undergone basic cleaning, indicating that the light dockage fraction could be used as a readily available matrix for the rapid screening of DON in wheat. This would eliminate the time required for additional sampling and preparation of whole grain, and move towards a truly rapid method for the screening of DON in wheat.

Background and objectives:The variability in gluten in non-gluten-containing grains (NGCG) processed using two preparation schemes was evaluated with the aim of minimizing effects of sample heterogeneity on gluten determined by enzyme linked immunosorbent assay (ELISA). The relationship between gluten concentration as determined by ELISA and visually assessed contamination of NGCG with wheat, durum, barley, and rye was investigated. Findings: Low variability between duplicate aliquots taken from test portions (0-30.6% relative standard deviation [RSD]) demonstrated the ELISA itself was precise. In the first scheme, variability among test portions ranged from 1% to 143% RSD, with only half in the range of 1-50%. Using scheme 2, variability in gluten among test portions ranged from 1% to 85% RSD, with more than three quarters in the range of 1-50%. High lipid content hemp seed was a particular challenge to grind, and this was reflected in higher variability in gluten results between test portions (mean RSD = 61%). Conclusions: Subsampling ground samples using rotary sample division and the use of a 1-g test portion in scheme 2 decreased the variability of gluten results for most samples. At concentrations relevant to existing thresholds of gluten contamination (e.g. 20 mg/kg), there was no relationship between gluten concentration in NGCG and cereal contamination as determined by visual inspection. Significance and novelty: This study provides guidance on how to improve the analysis of gluten contamination in NGCG by ELISA and describes the absence of a relationship between ELISA-determined gluten and the visual assessment of contamination in NGCG.