Resonance Rayleigh scattering study of interaction of hyaluronic acid with ethyl violet dye and its analytical application

In near weak acid to neutral medium, ethyl violet (EV) can react rapidly with hyaluronic acid (HA) to form a complex, which results in a significant enhancement of resonance Rayleigh scattering (RRS) and an appearance of a new spectrum, and the scattering wavelengths appear at 231, 274, 326, 498 and 640 nm. The maximum scattering wavelength appears at 326 nm. The RRS intensity is directly proportional to the concentration of HA in the range of 0.4–48.0 μg mL−1. A new method for the determination of trace amounts of HA based on the RRS method has been developed. The method exhibits high sensitivity, and the detection limit for HA is 9.6 × 10−2 μg mL−1. This method was applied for determining HA in eyedrops and in sodium hyaluronate injection samples with satisfactory results. Furthermore, the enhancement reasons of RRS and the relationship between RRS spectral characteristics of the HA–EV complex and its absorption spectrum have been discussed.