BUCHI ELS Detector C-650 - Manual (Page 17)

C-650 Operation Manual, Version B 4 Description of function 17
A plot of log I versus log m provides a linear response. The values of the constants (k and b) are
dependent on a variety of parameters (e.g. the temperature and the nature of the mobile phase).
An inlet to provide additional gas is located immediately before the detector chamber to provide
a concentric shield for the carrier gas. This serves to eliminate diffusion of the carrier gas and
eliminate contamination of the detection chamber.
4.3 Eluent flow splitting
The C-650 detector is designed to work with flow rates from 0.1 to 5 mL/min. In preparative chro-
matography applications, the flow rate is mostly higher than 5 mL/min. The BUCHI preparative
chromatography systems can deliver flow rates up to 250 mL/min. For preparative applications,
the eluent flow rate coming out of the chromatography column must be split into 2 different flow
rates:
• One part (usually about 1 mL/min) is directed to the C-650 and this part of the sample is
destructed by the evaporation and diffraction process.
• The other part is directed to the fraction collector to collect the detected compounds.
The working principle is shown below:
Pumping system
Co
lu
m
n
UV
Detector
(optional)
ELSD
Fraction
Collector
Flow splitter
≤ 250mL/min
≤ 5mL/min
Fig 4.6: Working principle of the flow splitting