Determination of proteins with ponceau G by compensating for the molecular absorption decreased resonance light scattering signals

Molecular absorption in an enhanced resonance light scattering (RLS) system decreases the enhanced RLS signals detected by using a common spectrofluorometer, lowering the detection sensitivity of RLS method. Thus a mathematical compensation for the decreased RLS signals resulting from the molecular absorption in the detection system is necessary so as to improve the detection sensitivity. Starting from Beer's law, herein we propose a compensation method by calculating a compensation factor related to the transmittance after the incident beam has passed through the absorption system. The compensation factor can be measured with an equipped accessory of the spectrofluorometer introducing a cell holder to change the propagation direction of the excitation light beam of the spectrofluorometer. By taking the interaction of Ponceau G (PG) with proteins as an example, we proved that the present compensation for the molecular absorption-decreased RLS signals could improve the detection sensitivity about two folds.