Which method is most suitable for accurately measuring low concentrations of proteins in a sample?

The BCA protein assay is the most suitable for accurately measuring low concentrations of proteins because it can detect as little as 0. 5 µg/mL and is less affected by detergents or other interfering substances. It works by reducing Cu²⁺ to Cu⁺ in the presence of protein, then forming a purple complex with bicinchoninic acid that absorbs strongly at 562 nm. The color change is stable for several hours, allowing precise spectrophotometric reading. For example, a 10 µg/mL protein sample will produce a clear purple color that can be measured reliably, giving accurate results for low‑concentration samples.