Standard substances free quantification makes LC/ESI/MS non-targeted screening of pesticides in cereals comparable between labs

•Six cereal matrices containing 134 pesticides (4–35 μM) were analysed.•Measurements were done on QQQ and ToF instruments in two independent laboratories.•Pesticide are quantified with predicted electrospray ionization efficiencies.•Quantitative results obtained in two labs were consistent with the R2 of 0.85. LC/ESI/MS is the technique of choice for qualitative and quantitative food monitoring; however, analysis of a large number of compounds is challenged by the availability of standard substances. The impediment of detection of food contaminants has been overcome by the suspect and non-targeted screening. Still, the results from one laboratory cannot be compared with the results of another laboratory as quantitative results are required for this purpose. Here we show that the results of the suspect and non-targeted screening for pesticides can be made quantitative with the aid of in silico predicted electrospray ionization efficiencies and this allows direct comparison of the results obtained in two different laboratories. For this purpose, six cereal matrices were spiked with 134 pesticides and analysed in two independent labs; a high correlation for the results with the R2 of 0.85.