What method is most commonly used to measure total protein?

The most commonly used method to measure total protein is the Biuret method. This technique is based on the principle that proteins react with copper ions in an alkaline solution to form a colored complex. The intensity of the color produced is directly proportional to the concentration of protein present in the sample, allowing for quantification.

The Biuret method is favored in clinical laboratories because it is relatively simple and provides consistent results across a range of protein concentrations. Additionally, the method is less susceptible to interference from other substances than some alternative techniques, which enhances its reliability in various biological samples.

The other methods listed, while useful in certain situations, do not typically serve as the primary method for total protein quantification. Dye binding is often used for specific protein assays but can be less accurate for total protein measurement. The Kjeldahl method is primarily used for determining nitrogen content in organic compounds, and while it can estimate protein levels, it is labor-intensive and less practical for routine clinical use. Refractometry measures the refractive index of solutions and is more commonly used for measuring certain solutes in a sample rather than total protein.