TESTA Analytical Solutions has introduced new laser options for its HK Series differential refractometer to enable precise determination of specific refractive index increment (dn\/dc) at the same wavelength as the light scattering application under investigation.<\/strong><\/p>\n

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Light scattering is a tried and trusted method for measuring molecular weight and therefore a widely used tool for analysing biopolymers, polymers and proteins. Most labs combine lightscattering detectors with chromatographic techniques such as Gel Permeation Chromatography \/ Size-Exclusion Chromatography (GPC\/SEC). When using a GPC\/SEC system with advanced detectors knowing the exact concentration of the sample at each data slice is very important. Accurately determining the dn\/dc value, which is highly wavelength dependent, is vital because it is the link that translates raw refractive index data to sample concentration<\/p>\n

The most accurate method of determining dn\/dc is to use a stand-alone batch instrument, such the HK Series differential refractometer, and to take measurements at different concentrations. While this uses more sample than on-line methods, it is not influenced by chromatographic parameters.<\/p>\n

The HK Series differential refractometer is a flexible device that may be used in either static or dynamic mode. In static mode, the specific refractive index (dn\/dc) of dissolved samples can be easily and precisely determined in just a few minutes. Beneficially, the system now offers a large number of wavelength options enabling precise matching of your light scattering detector laser operating wavelength, thereby ensuring reliable and reproducible results every time.<\/p>\n<\/div><\/section>
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