Cereal protein analysis via Dumas method: Standardization of a micro-method using the EuroVector Elemental Analyser

•Detection of influencing factors of Dumas method for cereal protein analysis.•Non-geometric Plackett–Burman experimental design.•Optimization of influencing factors.

The Dumas method (DM) of protein analysis in foods was standardized using two cereal references in order to identify the main sources of error during analysis; specifically, the study sought to establish which of the apparent critical factors (ACFs) were really significant influencing factors (IF) for the application of the DM to protein analysis in cereals.Using a non-geometric Plackett-Burman experimental design augmented to resolution IV via fold-over by increasing to twenty-four runs, the following eleven ACFs were investigated: sample weight (WS), capsule sealing process (CW), carrier gas flow (PC), purge gas flow (FHe), oxygen volume (O2), oxygen pressure (ΔO2), sample delay time (SD), sample run time (SR), front furnace temperature (FFT), rear furnace temperature (RFT), and GC oven temperatures (GCT).Two IFs were identified for each of the factors RFT and GCT, so an optimization process was carried out, based on a central composite design.Optimized conditions, ensuring enhanced accuracy and repeatability when determining protein content in cereals using the DM, are reported.