Methods of isolating and detecting metal ions from proteins
A method of detecting a metal ion in a protein-containing sample includes adding a protein degrading enzyme to the protein-containing sample to form an enzyme degradation product, adding an acid to the enzyme degradation product to provide a mixture, filtering the mixture to provide a supernatant, extracting the supernatant with an organic solvent to remove organic solvent soluble byproducts to provide a washed aqueous layer, and detecting the metal ion in the washed aqueous layer. The method is amenable to the detection of heavy metal ions in complex products such as milk. A kit includes reagents for performing the method.
1. A kit comprising:
a container for holding a protein-containing sample;
proteinase K;
concentrated nitric acid;
chloroform;
a handheld device for detecting metal ions, the handheld device employing detection based on giant magnetoresistance; and
instructions for performing the isolation of metal ions from the protein-containing sample.
2. The kit of claim 1 , wherein the kit is a small scale kit for performing the isolation of metal ions in the field.
3. The kit of claim 1 , further comprising other protein denaturing agents.
4. The kit of claim 3 , wherein the further protein denaturing agents comprise at least one selected from the group consisting of sodium dodecyl sulfate (SDS), urea, ethylenediamine tetraacetic acid, trypsin, and chymotrypsin.