28
Figure 25.
Electrolytic conductivity detector: propanol tankwith pump.
ToCell
ToPump
Drain fromCell
Out of Pump
Propanol
Pump
Figure 26.
With any detector, always be sure that gas flows are adjusted properly.
PIDMakeup
H
2
PIDPurge
ELCDMaintenance andTroubleshooting:
ELCD performance depends on the reactor tem-
perature, the volume of the conductivity cell, the propanol flow rate, the hydrogen gas flow
(Figure 26), and the purity of the solvent system. The goal is tominimize tailing asmuch as
possiblewithout losing sensitivity. Depending on the amount of use and the types of sam-
ples analyzed, the nickel reaction tube – the reaction catalyst – should be replaced as often
asmonthly. Hydrocarbons and certain other compounds can “poison” the reaction tube and
reduce its catalytic activity. Oxygen andmoisture can oxidize the reaction tube, affecting
sensitivity. High-purity hydrogen gas is critical for a stable baseline. Use gas regulatorswith
stainless steel diaphragms and the proper purifiers for reaction gases.
A drop in sensitivity (particularly for brominated compounds), baseline instability, or
appearance of unknown peaks indicate it might be necessary to replace the reaction tube.
Reconditioning the reaction tubemight restore baseline stability: disconnect theTeflon
®
transfer line, then increase the reactor temperature to 1000°C for one hour, then reset the
reaction temperature to 900°C for re-calibration.
Ultra-High-Purity Brass
LineRegulator
• Usewherever you
need to reduce the
line pressure by
20psi ormore.
• Same purity level
as high-pressure
cylinder regulators.
*Please order appropriatemale connector,
pipe-to-tube fittings; see our catalog.
Fitting
qty.
cat.#
1
/
4
" female NPT ports*
ea.
21666
