Fractionation metallothionein-like proteins in mussels with on line metal detection by high performance liquid chromatography-inductively coupled plasma-optical emission spectrometry

A rapid method for the determination of Al, Ba, Cu, Fe, Mn, Sr and Zn binding metallothionein-like proteins (MLPs) in mussels (Mytilus galloprovincialis) by inductively coupled plasma-optical emission spectrometry was developed. The method uses a short column (8 mm x 75 mm) anion exchange high performance liquid chromatography (HPLC) with inductively coupled plasma-optical emission spectrometric (ICP-OES) detection. Working in isocratic mode (75 mM Tris-HCl at pH 7.4, flow rate at 0.8 ml min(-1)), two major MLPs isoforms (MLP-1 and MLP-2) can be separated in ten minutes. The distribution of basal metals binding MLPs was assessed by on line HPLC and ICP-OES, while the basal contents of metals binding MLPs were obtained after off line HPLC and ICP-OES (collection of the two major fractions and multi-element determination by ICP-OES). The calculated LODs were 81, 6, 10, 13, 30, 9 and 123 ng g(-1) for Al, Ba, Cu, Fe, Mn, Sr and Zn binding MLP-1 and MLP-2, respectively. The repeatability of the over-all method (five different mussel cytosols prepared from the same mussel sample and subjected to the off line HPLC-ICP-OES procedure twice) was from 11.2 for Cu to 16.2% for Zn. The method was finally applied to different raft mussels from Ria de Arousa estuary in order to know basal levels of elements binding MLPs. (c) 2006 Elsevier B.V All rights reserved.