Accurately quantifying total protein concentration is a key to most experiments and is often necessary for isolation, separation, and analysis of proteins by biochemical methods. When it is necessary to determine the total protein concentration in a sample, one of the first factors to consider is the selection of a protein assay method. The choice among available protein assays typically is based upon the compatibility of the method with the samples to be assayed. We offer assay reagents, kits and standards to determine total protein concentration of samples containing different buffer components for protein quantitation using both fluorescence-based and colorimetric assays.

Protein assay selection guide

No one reagent can be considered to be the ideal or best protein assay method. Each method has its advantages and disadvantages. Use the chart below to help select the best protein assay for your application based on the sample composition and your preferred method.

Understand your sample’s purity and concentration

The Thermo Scientific™ NanoDrop™ One UV-Vis Spectrophotometer and the Invitrogen™ Qubit™ 3 Fluorometer, when used together, provide the ability to obtain the most complete information about the concentration and quality of your DNA, RNA, or protein sample. Knowing the precise concentration and purity of your sample early helps you prevent costly troubleshooting and rework downstream.

Choose the platform that is right for you


We offer high-quality, easy-to-use protein standard solutions to serially dilute to create assay standard curves to measure protein concentration

We have developed specialized protein assay reagents and kits to estimate and measure specific post-translational modification (PTM) or functional (enzymatic) classes of proteins in biological samples, including glycoproteins and phosphoproteins.


We offer easy-to-use colorimetric or fluorescent peptide assays that are designed specifically to improve the sensitivity and reproducibility of quantitation of peptide mixtures.

We offer various colorimetric and fluorescent reagents to accomplish pre-column and post-column derivatization of peptides and amino acids for analysis by HPLC detectors; includes vacuum hydrolysis tubes and quantitation standards.


For target-specific protein quantification, we offer Novex® reagents and solutions for immunodetection-based assays including western blot analysis, ELISA, and Luminex® multiplex bead-based assays and instruments.