Development of a method for the detection of zinc in Brassica oleracea using solid phase extraction and size-exclusion chromatography inductively coupled plasma mass spectrometry (SEC-ICP-MS).

The aim of this work is the development of a suitable method to extract and detect zinc-bound compounds from cabbage, broccoli and kale (family Brassicaceae, species oleracea) using solid phase extraction (SPE) and size-exclusion chromatography inductively coupled plasma mass spectrometry (SEC-ICP-MS). Tris [2-Amino-2-(hydroxymethyl)-1,3-propanediol]/hydrochloric acid (Tris/HCl) or ammonium nitrate were used as extractants added to the freeze-dried samples, which were then sonicated and centrifuged. An enzymatic mixture was added to the extracts and then incubated for 5- and 18 h prior to analysis by SEC-ICP-MS. Results showed a good coefficient of variation (CV) of the elution time (0.06-0.9%), concentration (4.7-16.9%) and molecular size (0.4-5.4%). The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.9 μg L-1 and 2.8 μg L-1, respectively. The proposed method is reliable and robust and can be applied to samples with difficult matrices like vegetables and soil.•Good precision, stability and reproducibility.•Easy to execute and suitable for analysis of vegetables and other samples with complex matrices, eg. soil.•This method contributed to good maintenance of the instrument and to minimal cleaning time.