HPLC-Chip-Multiple Reaction Monitoring (MRM) method for the label-free absolute quantification of γ-conglutin in lupin: Proteotypic peptides and standard addition method

► This study presents a HPLC-Chip-MRM label-free method for the absolute quantification of γ-conglutin. ► Gamma-conglutin has a hypoglycaemic activity and it is a major lupin allergen. ► The standard addition approach is useful to evaluate the matrix effect. ► The standard addition approach is applied to the development of a label-free absolute quantification method in proteomics. ► The final output of the study is a robust external calibration curve for the quantification of the bioactive γ-conglutin.