When it is necessary to determine total protein concentration of a sample, one must first select an appropriate protein assay method based upon its compatibility with the samples type. The objective is to select a method that requires the least manipulation or pre-treatment of the samples to accommodate substances that interfere with the assay. Each method has its particular advantages and disadvantages. Because no one reagent can be considered the ideal or best protein assay method for all circumstances, most researchers have more than one type of protein assay available in their laboratories.
Important criteria for choosing an assay include:
Compatibility with the sample type and components
Assay range and required sample volume
Protein-to-protein uniformity (see below)
Speed and convenience for the number of samples to be tested
Availability of spectrophotometer or plate reader necessary to measure the color produced (absorbance) by the assay