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dn/dc and UV Extinction Determination

ASTRA has several different methods for determining the dn/dc or UV extinction coefficients for your sample:

Direct measurement

dn/dc determination

Inject aliquots of known concentration into an Optilab refractometer or UV detector. ASTRA provides experiment methods for determining dn/dc or UV extinction coefficients. Define baselines, set peak regions with concentrations, then view the corresponding analysis procedure to determine dn/dc or UV extinction.

On-line measurement

If the assumption can be made that 100% of the injected mass reaches the Optilab or UV detector, it is possible to calculate the dn/dc or UV extinction coefficient on-line.

Alternately, if an Optilab and UV detector are used in combination, and the dn/dc value is known for the sample, ASTRA can calculate a UV extinction coefficient for the sample.

RI Calibration

If a third-party RI detector is being used, ASTRA provides an experiment template to calculate the RI calibration constant for the analog input signal.



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Wyatt Technology is the recognized leader in light scattering instrumentation and software for determining the absolute molar mass, size, charge and interactions of macromolecules and nanoparticles in solution.

Wyatt's line of multi-angle static light scattering products couple to size exclusion chromatography (SEC-MALS), field-flow fractionation (FFF-MALS), and stop-flow composition-gradient systems (CG-MALS). Our dynamic light scattering (DLS) products operate in traditional cuvette as well as on-line and automated, high-throughput modes. We also offer unique instruments for electrophoretic light scattering (MP-PALS), differential refractometry, and differential viscosity.

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