Abstract: A bridge viscometer for measuring specific viscosity, ?sp(t), includes four capillaries, a delay volume, and a pressure transducer. The pressure transducer generates a signal indicative of a pressure differential, ?p(t), as a sample is introduced into the bridge viscometer. The specific viscosity, ?sp(t), of the sample is calculated based on the pressure differential, ?p(t), and a predetermined internal pressure, IP0.

Abstract: A bridge viscometer for measuring specific viscosity, ?sp(t), includes four capillaries, a delay volume, and a pressure transducer. The pressure transducer generates a signal indicative of a pressure differential, ?p(t), as a sample is introduced into the bridge viscometer. The specific viscosity, ?sp(t), of the sample is calculated based on the pressure differential, ?p(t), and a predetermined internal pressure, IP0.

Abstract: A thermally controlled stage is connected within one arm of a bridge of a capillary bridge viscometer so that the bridge can be balanced in situ to provide accurate measurement signals. The thermally controlled stage includes a tuning capillary tubing portion that is wrapped around a thermally conductive core. A resistance heater or a Peltier thermoelectric device is located in close proximity to the capillary tubing portion. The heater or Peltier device and the capillary tubing portion are located within a thermally insulated housing. The heater or Peltier device varies the temperature of the capillary tubing portion to cause a corresponding change in the flow impedance of the tuning capillary tubing portion of the arm of the bridge in which the thermally controlled stage is connected. The temperature of the tuning capillary tubing portion is monitored and adjusted until any pressure differential across the bridge is eliminated, whereby to trim in the balance of the bridge.

Abstract: An improved differential refractometer incorporating a photodetector array is disclosed. Using a multi-element photo array provides the basis for measurement of differential refractive index values with a heretofore unattainable combination of sensitivity of measurement and concurrent range of measurement. Within the large dynamic range attainable, the detector structure provides equal sensitivity irrespective of deflection within the range. The transmitted light beam is tailored to provide a spatial variation of the light intensity at the array improving thereby the precision of measurement of its displacement. This in turn results in improved precision in the reported differential refractive index and in the calculation of the differential refractive index increment dn/dc. Integrating the detector array into the flow cell structure of the parent case results in a detector of exceptional sensitivity and range for sample quantities far smaller than required by conventional differential refractometers.

Abstract: Chromatographic separations are often characterized by multiple detectors though which the sample flows serially. As the sample flows between detectors, it becomes progressively diluted due to mixing and diffusion. This phenomenon is traditionally called “band broadening” and often results in significant distortion of the calculated physical properties such as molar mass and size. This is particularly true for the case of monodisperse samples such as proteins. A new procedure is described whereby most types of band broadening may be corrected resulting in more accurate calculations of such physical properties. The conventional means for correcting band broadening effects is based upon mathematical procedures that attempt to narrow the broadened peak to its prebroadened form. Such procedures are notoriously unstable and often result in unphysical results such as ringing, negative concentrations, or negative scattered intensities.