Protein Quantification by Elemental Mass Spectrometry: An Experiment for Graduate Students

A multiday laboratory experiment was designed to integrate inductively coupled plasma-mass spectrometry (ICP-MS) in the context of protein quantification into an advanced practical course in analytical and environmental chemistry. Graduate students were familiar with the analytical methods employed, whereas the combination of bioanalytical assays with ICP-MS is rare. Small groups of graduate students quantified ovalbumin in hen egg white using metal-coded affinity tagging (MeCAT). Proteins were covalently labeled with lanthanide chelate complexes and quantified according to the lanthanide content by ICP-MS using internal and external standards. The results were in good agreement with reference values. As an alternative approach, a Bradford assay was used for determination of the ovalbumin content of the internal standard. The chosen workflow provides hands-on experiences for the students in principles of analytical chemistry, quantitative protein analyses, gel electrophoresis, ICP-MS, calibration, and data handling. The experiment constitutes a research-oriented approach as students apply their knowledge and skills in new contexts.