Rapid multi-element characterization of microgreens via total-reflection X-ray fluorescence (TXRF) spectrometry

Microgreens are an emerging class of vegetables, which have become increasingly important in the agri-food market in recent years, and contain a number of macro- and micro-nutrients. This paper presents a rapid method for the elemental analysis of microgreens based on total reflection X-ray fluorescence (TXRF) spectroscopy, without preliminary sample digestion. The following elements were detected and quantified simultaneously for six microgreen genotypes, belonging to Asteraceae and Brassicaceae: P, S, K, Ca, Cl, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr. The limit of detection (LOD) varied depending on the element and ranged between 0.1 mg kg−1 for Sr and 42 mg kg−1 for P. The method was validated using certified standards, and results compared with those obtained using a conventional ICP-AES method requiring sample digestion. The paper also presents the advantages and disadvantages of the two techniques.