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.

For further information on the HK Series Differential Refractive Index (DRI) detector please visit https://www.testa-analytical.com/gpc-sec-chromatography.html or contact Testa Analytical Solutions on +49-30-864-24076 / rcarano@testa-analytical.com.