Application of covalent affinity chromatography with thiol-disulphide interchange for determination of environmental exposure to heavy metals based on the quantitative isolation of Cd-thionein from human breast milk.

The aim of this study was to test a new chromatographic method for the quantitative determination of Cd-thionein (Cd-Th) in human breast milk, in order to determine the level of exposure to heavy metals. Cd-thionein was isolated by covalent affinity chromatography with thiol-disulphide interchange, which is a modern separation technique of high affinity, good repeatability and reproducibility, allowing specific isolation of the thiolproteins. The fundamentals of indirect determination of the contents of metallothionein protein from human milk were worked out through estimation of the quantities of cadmium bound with Cd-thionein and adsorbed on covalent affinity chromatography gel during a separation process.