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Differential Refractometer for Quantifying Protein in Samples

publication date: Jul 15, 2021
author/source: TESTA Analytical Solutions



The HK Series Differential Refractive Index (DRI) detector from TESTA Analytical has been shown to provide accurate and reliable measurement of the absolute concentration and total mass of protein in a sample.

Quantifying the amount of protein is highly desirable before processing protein samples for isolation, separation and analysis using chromatographic techniques.

Refractive index is one of the most commonly used detectors in GPC/SEC and HPLC systems. A key parameter for translating RI detector output to exact sample concentration is the dn/dc value, or specific refractive index increment.  The dn/dc value is unique for each sample-solvent combination, as it represents the difference in refractive index between the sample and the solvent.

The HK Series DRI detector is an exceptionally stable differential refractometer, operating from room temperature to 80°C, that may be used in either static or dynamic mode. In static mode, the specific refractive index increment (dn/dc) of dissolved protein samples can be easily and precisely determined in just a few minutes. The specific refractive index increment is also a critical parameter required to determine absolute molecular weight using static light scattering (SLS) detectors. This is because a relatively small error in dn/dc determination will lead to twice the error in calculating molecular weights. It is important also to determine the dn/dc value at the same wavelength as the SLS detector laser or a further error will be introduced, as dn/dc is strongly dependent on operating wavelength. The HK Series DRI detector offers a large number of wavelength options to enable precise matching of your SLS detector laser operating wavelength, thereby ensuring reliable andreproducible results every time.

Where the dn/dc value of your protein sample is already known, the HK Series DRI detector can be used for precise and sensitive protein concentration determination. The protein sample used for this measurement can usefully easily be collected, saved and used for further investigations.


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Testa Analytical Solutions e.K

Testa Analytical Solutions e.K. is a company dedicated to supplying the best possible instrumental solutions for characterization of polymers, particles, nanomaterials and proteins. Drawing upon over 30 years’ experience of technologies serving these markets, the staff at Testa Analytical are happy to share their knowledge with researchers worldwide to help provide them with a working solution for even the most demanding applications.


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