Inverse Abbe-method for observing small refractive index changes in liquids

• Published in: Talanta (Oxford) 2015-05, Vol.137, p.143-147
• Main Authors: Räty, Jukka, Peiponen, Kai-Erik
• Format: Article
• Language: English
• Subjects: Abbe refractometer; Dispersions; Ethyl alcohol; Inverse; Inverse Abbe method; Light dispersion; Liquids; Monitoring; Reflection spectrum; Refractive index; Refractivity; Spectra; Water purity
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2015.01.023

This study concerns an optical method for the detection of minuscule refractive index changes in the liquid phase. The proposed method reverses the operation of the traditional Abbe refractometer and thus utilizes the light dispersion properties of materials, i.e. it involves the dependence of the refractive index on light wavelength. In practice, the method includes the detection of light reflection spectra in the visible spectral range. This inverse Abbe method is suitable for liquid quality studies e.g. for monitoring water purity. Tests have shown that the method reveals less than per mil NaCl or ethanol concentrations in water. [Display omitted] •The refractive index of substances has been used in various applications e.g. in liquid purity testing.•Refractometers commonly operate according to the Abbe principle.•We reverse the traditional Abbe principle to detect tiny refractive index changes in liquids.•The inverse Abbe method was applied to water purity monitoring.•Less than per mil NaCl or ethanol concentration in water was detected.