BI-DNDC

Differential Refractometer

Product Description

The BI-DNDC is a deflection type refractometer that may be purchased for use in either batch or GPC/SEC mode. In batch mode, the specific refractive index increment, dn/dc, is determined. This value is required as a parameter in molecular weight measurements using light scattering. In GPC/SEC mode, dn/dc is already known, and the instrument is used as a concentration detector for GPC/SEC applications.

Features

All major features are user programmable in order to achieve the maximum flexibility. The BI-DNDC can be set using the front panel controls and read using the LED readout or by an external computer. It includes a microprocessor, which allows user-friendly handling of all functions of the instrument, as well as refractive index and temperature data transfer to a personal computer via a standard serial interface.

Most importantly, warm-up time for the BI-DNDC is only one hour, much less than other models on the market.

Determination of dn/dc

The dn/dc determination requires calibration of the batch mode instrument with a solvent/solute combination with known dn/dc, typically KCl in water. The calculated constant is not solvent dependent and may be used for all further measurements. In batch mode, the instrument comes with BI-DNDCW software for use with an external PC. Included with the BI-DNDC instrument is a syringe kit with PEEK and Teflon tubing, fittings and syringes.

Sample may be recovered and reconstituted, if required. Typically, five or more concentrations, ranging from 0.1 to 10 mg/mL, are recommended. New instrument readings can be performed in a matter of minutes since it only takes ~ 0.5 mL of liquid to flush out the previous sample.

Determination of concentration

In this mode, the BI-DNDC serves as a highly sensitive concentration detector. Even better, with the right wavelength and the BI-MwA, the BI-DNDC becomes part of a system that eliminates GPC/SEC column calibration.

Specifications

Cell Angle: 45
Cell Volume: 8 L
Dead Volume (Inlet to Cell/Cell to Outlet): GPC mode sample cell: 0.25 L, GPC mode reference cell: 100 L; Batch mode sample cell: 100 L; Batch mode reference cell: 100 L.
Measurement Ranges (ΔRIU Full Scale)(GPC mode): 6x10 ^-4, 3x10 ^-4, 1.5x10 ^-4, 7.5x10 ^-5, 3.75x10 ^-5, 1.87x10 ^-5, 9.3x10 ^-6, 4.6x10 ^-6, 2.3x10 ^-6
n₀ range: 1.0 to 1.75 RIU
Sensitivity (GPC mode): 1.5 ng (Fructose in H₂O)
Noise Level: < 2.5 x 10 ^-9, ΔRIU, 25 C
Temperature Accuracy: 0.5 C
Temperature Stability: 0.01 C
Temperature Range: Ambient to 80 C
Specify Wavelength: 620 nm, 535 nm or 470 nm, factory set
Tubing I.D.: GPC mode sample cell: 0.25 mm, GPC mode reference cell: 0.5 mm; Batch mode sample cell: 0.5; Batch mode reference cell: 0.5 mm.
Flow Rate (typ./max.): 1.0/3.0 mL/min (Analytical Mode), 5.0/12.0 mL/min (Prep. Mode)
Time Constant: 0.1 to 2 seconds
Analog Signal Output: 1 and 10 volt bipolar, full scale
Digital Signal Output: RS-232/COM port
Software: BI-DNDCW for batch mode measurements
Data Transfer Rate (baud): 4800, 9600, 19200, 38400, 57600, 115200
Digital Inputs: Flush, Zero, Sync, Error
Weight: 8 kg
Size: 160 x 175 x 340, mm

A policy of continued improvement may lead to specification changes.

Options and Accessories

BI-SFTK: Syringes, fittings and tubing kit