Bischoff Analysentechnik und -geräte GmbH - Differential Refractive Index Detector RI 8120
| Year of introduction
Bischoff Analysentechnik und -geräte GmbH
Chromatography: LC-Detector: Refractive Index
Designed for high sensitivity
For highest sensitivity and baseline stability the RI detector 8120 for HPLC has been designed as a differential refractometer detector. It measures continously the differential refractive index Dn between the pure eluent and the eluate from the HPLC column in its differential flow cell. Key properties are in the highly symmetric construction of the optical bench and a build-in heat exchanger which guarantee very small temperature effects on the baseline..
Many analytical applications
Since the volume of the flow cell is 8 µL only, the RI detector 8120 meets all the requirements for high resolution chromatographic separations. No additional peak broadening can be observed with standard 250 x 4.6 mm columns.
For preparative applications the modified model 8120P is available.
Due to the very low heat dissipation of the LED and due to the construction of the optical bench the RI detector 8120 has an outstanding temperature stability. Therefore, no external thermostatting is required.
Linearity and stability
The optics of the RI detector 8120 are designed to give the highest possible linearity. Therefore, a long wavelength almost light emitting diode (LED with l=950 nm) is used instead of a white tungsten lamp.
The use of a LED also avoids non-linearity caused by dispersion effects. In addition to that, silicon photodiodes have been built into the instrument as sensors for the position of the light beam. This position is then converted into an electrical signal in a highly linear way.
Functionality and Simplicity of Operation
The reference (i.e. eluent) channel of the differential refractometer detector RI 8120 is flushed from the sample channel by a push-button actuated 2-way valve. Thus, a second (reference) flow system is avoided. Operation of the RI 8120 is further simplified by the build-in option to perform a complete optical and electrical auto-zeroing by pressing a single push-button.
For Modell RI 8120 and RI 8120 P
0, 1, 2, 5, 20, 50, 100, 200, 500, 1000, 2000 DRI
Noise (Cell filled with water)
±2 x 10-8Dn
Baselinedrift at constant temperature
1 x 10-7Dn/h
Wavelength of light source
950 nm ± 20
Auto zero range
±1% from total sensitivity range
0.05 s / 0.1 s / 0.5 s / 2 s
0 - 100 mV
0 - 1 V
- internal +10 mV
- external +5 mV
Flow cell (Modell 8120)
- volume 8 µl
- angle of deflection 45°
- pressure limit 0.02 MPa
Flow cell (Modell8120P)
- volume 22 µl
- angle of deflection 5°
- pressure limit 0.02 MPa
15 - 50°C
Filling of the reference cell
c) time constant
5 digit LED display
- by contact closures: autozero, marker
- by current loop or via RS232: all functions
110 / 220 V ± 10%
50 / 60 Hz
381 x 255 x 130 mm