A Truth About Protein Detection And Analysis

Whenever protein detection and analysis is referred to, many of us who are working in bioanalytical technology and method development often mistakenly believe that such detection and analysis must be quantitative. As a matter of fact, to biomolecular researchers, most frequently, protein detection and analysis only needs to be qualitative, or relatively-quantitative. 

With such stringent conditions, it is extremely difficult to determine the absolute quantity of a target protein. Despite this fact, there are numerous products in the market that are based on ELISA (enzyme-linked immunosorbent assay) or other similar immunoassay technique for “quantitative” detection and analysis of proteins. Are these methods truly “quantitative”? The answer, unfortunately, very often, may be a “no”. Please refer to Application Note 2: A comparison between NanoDLSay and ELISA, to find further explanation. 

Despite these obvious difficulties, why there is such a fervent belief on the necessity of quantitative detection of protein molecules? This is because bioanalytical chemistry was derived from traditional quantitative chemical analysis. Small chemicals and ions are usually very stable and they usually have much less interactions with their surrounding environment than proteins. The “quality” and “quantity” of small molecules and ions are not significantly affected by the environment as a protein would. Furthermore, the detection of small chemicals and ions is usually done on relatively simple samples, such as water, and there is much less interference from the sample matrix to the analysis. This is why it is relatively easier to develop standard solutions for small chemicals and ions, and one standard solution can often be used for the analysis of samples in different matrices. Under these conditions, the quantitative analysis of small chemicals and ions is reliable.