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.
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.
Features at a glance
- Fast instrument warm-up, ~ 1 hour!
- Sensitivity, 2.5 x 109 ΔRIU
- Reference cell flush
- 9 measurement ranges
- DNDCW Windows™ software
- Active temperature control to 80 °C
- Wavelength selection: 620, 535 or 470 nm
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.
|Cell Volume (Batch Mode)
|Dead Volume (Inlet to Cell/Cell to Outlet)
||GPC Mode Sample Cell: 0.25 µL, GPC Mode Reference Cell: 100 µL
|Batch Mode Sample Cell
||100 µL: Batch Mode Reference Cell: 8 µL
|Measurement Ranges (ΔRIU Full Scale)(GPC mode)
||6×10-4, 3×10-4, 1.5×10-4, 7.5×10-5, 3.75×10-5, 1.87×10-5, 9.3×10-6, 4.6×10-6, 2.3×10-6
||1.0 to 1.75 RIU
|Sensitivity (GPC Mode)
||1.5 ng (Fructose in H2O)
||< 2.5 x 109, ΔRIU, 25 °C
||± 0.5 °C
||± 0.01 °C
||Ambient to 80 °C
||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 mm
|Batch Mode Reference Cell
|Flow Rate (typical/maximum)
||1.0/3.0 mL/min (Analytical Mode), 5.0/12.0 mL/min (Preparation Mode)
||0.1 to 2 seconds
|Analog Signal Output
||1 and 10 volt bipolar, full scale
|Digital Signal Output
||BI-DNDCW for Batch Mode measurements
|Data Transfer Rate (baud)
||4800, 9600, 19200, 38400, 57600, 115200 Digital Inputs: Flush, Zero, Sync, Error
||160 x 175 x 340, mm
A policy of continual improvement may lead to specification changes.