An Innovative Use of the QuEChERs Method and LC-MS/MS Technique for Fast and Simple Determination of Quinolizidine Alkaloids in Leguminous Plants

Quinolizidine alkaloids, found particularly in leguminous plants (<i>Fabaceae</i>), are known for their role in plant protection, acting as toxic secondary metabolites against pests and pathogens. However, their toxicity also makes them anti-nutritional factors in food and feed. Therefore, it is necessary to monitor their presence. The aim of this study is to optimise two stages of the research procedure, i.e., (1) the conditions of LC-MS/MS instrumental analysis for the simultaneous determination of five alkaloids: angustifolin, hydroxylupanine, sparteine, and two geometric isomers of lupanine and isolupanine, and (2) the extraction and isolation stage of six different leguminous matrices: field beans, peas, lupins (narrow-leaved, white, yellow) and lentils. The modified and validated QuEChERS method based on LC-MS/MS shows acceptable recoveries (71-115%) with relative standard deviation <15%. A slight matrix effect (-20-14%) was observed. The uncertainty of the method <28%. The developed method shows significant progress in terms of sensitivity, achieving a detection limit as low as 0.01 mg/kg. This is a significant improvement over existing analytical methods and highlights the great potential of this method for detecting trace amounts. The innovative, sensitive, and selective method, offering simplicity and speed, was applied to the analysis of real leguminous samples.