MICRODETERMINATION OF PROTEINS BY RESONANCE LIGHT-SCATTERING SPECTROSCOPY WITH TETRAIODO PHENOL SULFONAPHTHALEIN

The reaction of tetraiodo phenol sulfonaphthalein (TIPSP) with protein s results in an enhanced resonance light scattering (RLS) at 334 nm. T his is the foundation of a new quantitative determination method for p roteins in aqueous solution. The assay is characterized by high sensit ivity (0.34-12.24 mu g/ml), short reaction time (< 2 min) and simplici ty (one-step assay). The protein-to-protein variability of the method was investigated, which had some relationships with the isoelectric po ints of the proteins. There is little or no interference from amino ac ids, from most metal ions and from complexing agents (e.g. EDTA). Inte rference by some metal ions, detergents and salts can be minimized by dilution. Human serum samples were measured by this method and the res ults were compared with a traditional method.