Which factor is most likely to cause a falsely low result when using the BCG dye-binding assay?

The BCG dye-binding assay is a method used to measure albumin levels in blood serum. In this assay, bromcresol green (BCG) dye binds to albumin, and the intensity of the color developed is proportional to the concentration of albumin in the sample. However, certain substances present in the sample can interfere with this measurement.

The presence of penicillin is known to have a binding affinity for the BCG dye, which can result in a competition between penicillin and albumin for the dye. When penicillin binds to the dye, it can reduce the amount of dye available to bind with albumin, leading to a falsely low result for albumin concentration. This interference primarily occurs because the assay relies on the accurate binding of the dye to albumin; any other substance competing for this binding can distort the results.

In contrast, other factors such as incubation time, bilirubin, or lipemia may cause variability in results, but they do not specifically compete with BCG dye for binding in the same manner as penicillin, nor do they directly reduce the dye's ability to interact with albumin to the extent that penicillin does. Thus, penicillin is particularly significant in this context as it leads to a more predictable and