High-performance liquid chromatography coupled with array inductively coupled plasma optical emission spectrometry for the separation and simultaneous detection of metal and non-metal species in soybean flour

Abstract

Biological samples (soybean flour extracts) were subjected to a separation/detection process using size-exclusion chromatography (SEC) coupled with ICP-OES with the aim of obtaining information about possible binding forms of selected trace metals. An array ICP-OES instrument with a segmented charge coupled device detector was used which simultaneously monitors element emission lines and the spectral background. In addition to the trace metals, the non-metals P and S were included to obtain further information about the binding sites of the trace metals in the matrix. Two SEC columns with different packing materials coupled with ICP-OES were compared in terms of performance and influence on native species composition. Recoveries of the eluting metals were evaluated by a post-column injection technique. In the soybean flour extract, Cu and Zn were predominantly present in the 10–16 kDa fraction. Two Mn and P signals were located in the 17–31 kDa range, S was eluted with the exclusion volume of both SEC columns (100 and 70 kDa, respectively) as well as in the 20 kDa range. The effects of chromatographic technique and column type on recoveries and species composition are discussed.