BUCHI ELS Detector C-650 - Manual (Page 39)

C-650 Operation Manual, Version B 6 Operation 39
6.2.2 External
To auto-zero the detector, a contact closure signal or a TTL signal is used to short circuit the
contacts. The signal should be at least 1 second long, with a maximum current of 20 mA at 5 V.
If a TTL signal is used please make sure to use the correct polarity identified on the cable.
6.3 Routine operation of the detector
In general, operation of a Chromatography system with Evaporative Light-Scattering Detection is
similar to operation of the system with other detectors.
During operation of the detector, the following should be considered:
CAUTION
Risk of minor or moderate injury by hot acid fumes.
• Do not operate the system with faulty parts
• Check device setup for proper sealing before use
• Do not inhale process fumes
• Operate the device inside an active fume hood
• Do not move the device or parts of it during operation
NOTICE
Risk of device damage by leaking liquids.
• Do not operate the system with faulty parts
• Check device setup for proper sealing before use
• Make sure that there is a continuous flow of gas through the detector (i.e. no constriction). If
a vacuum is used, ensure that the vacuum effect will not disturb the detector (section 5.4).
• Ensure that the siphon is filled with liquid at all times. The overflow from the siphon should be
collected in a suitable container.
• Make sure that all flow connections are properly tight. In case of any leak, switch off the
pump immediately and remove the liquid.
• Never exceed a gas pressure of greater than 4.5 bar (67 psi).
• Avoid the use of solvent or compounds that could corrode the detector. The mobile phase is
in contact with glass and PTFE tubing and the evaporation tube is made of stainless steel.
6.4 Optimizing the performance
6.4.1 Selecting the optimum temperature
There are two factors that should be taken into account when selecting the optimum tempera-
ture for the detector:
• Increasing temperature will optimize the evaporation of the mobile phase.
• Decreasing temperature will minimize the decomposition of thermally labile compounds and
the volatilization of semi-volatile compounds.
A very reasonable start is to set the temperature to 60 °C if an aqueous mobile phase is used
and 40 °C if an organic mobile phase is used (these temperatures are suggested for a flow rate
of 1 mL/min). At higher flow rates, more elevated temperatures may be required to minimize the
noise.