ASTM E1698-95(2000)
(Practice)Standard Practice for Testing Electrolytic Conductivity Detectors (ELCD) Used in Gas Chromatography
Standard Practice for Testing Electrolytic Conductivity Detectors (ELCD) Used in Gas Chromatography
SCOPE
1.1 This practice covers testing the performance of an electrolytic conductivity detector (ELCD) used as the detection component of a gas chromatographic system.
1.2 This practice is directly applicable to electrolytic conductivity detectors that perform a chemical reaction on a given sample over a nickel catalyst surface under oxidizing or reducing conditions and employ a scrubber, if needed, to remove interferences, deionized solvent to dissolve the reaction products, and a conductivity cell to measure the electrolytic conductivity of ionized reaction products.
1.3 This practice covers the performance of the detector itself, independently of the chromatographic column, in terms that the analyst can use to predict overall system performance when the detector is coupled to the column and other chromatographic system components.
1.4 For general gas chromatographic procedures, Practice E260 should be followed except where specific changes are recommended herein for the use of an electrolytic conductivity detector. For definitions of gas chromatography and its various terms see Practice E355.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E1698–95 (Reapproved 2000)
Standard Practice for
Testing Electrolytic Conductivity Detectors (ELCD) Used in
1
Gas Chromatography
This standard is issued under the fixed designation E 1698; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope unique conditions, in particular its different modes of selectiv-
ity,itistheintentofthispracticethatacompletesetofdetector
1.1 This practice covers testing the performance of an
specifications should be obtained at the same operating condi-
electrolytic conductivity detector (ELCD) used as the detection
tions, including geometry, gas and solvent flow rates, and
component of a gas chromatographic system.
temperatures. It should be noted that to specify a detector’s
1.2 This practice is directly applicable to electrolytic con-
capability completely, its performance should be measured at
ductivity detectors that perform a chemical reaction on a given
several sets of conditions within the useful range of the
sample over a nickel catalyst surface under oxidizing or
detector. The terms and tests described in this practice are
reducing conditions and employ a scrubber, if needed, to
sufficiently general so that they may be used at whatever
remove interferences, deionized solvent to dissolve the reac-
conditions may be chosen for other reasons.
tion products, and a conductivity cell to measure the electro-
3.2 Linearity and speed of response of the recorder used
lytic conductivity of ionized reaction products.
should be such that it does not distort or otherwise interfere
1.3 This practice covers the performance of the detector
with the performance of the detector. Effective recorder re-
itself, independently of the chromatographic column, in terms
sponse should be sufficiently fast so that it can be neglected in
that the analyst can use to predict overall system performance
sensitivity of measurements. If additional amplifiers are used
when the detector is coupled to the column and other chro-
between the detector and the final readout device, their
matographic system components.
characteristics should also first be established.
1.4 For general gas chromatographic procedures, Practice
E 260 should be followed except where specific changes are
4. Principles of Electrolytic Conductivity Detectors
recommended herein for the use of an electrolytic conductivity
4.1 The principle components of the ELCD are represented
detector. For definitions of gas chromatography and its various
in Fig. 1 and include: a control module, a reactor assembly,
terms see Practice E 355.
and, a cell assembly.
1.5 This standard does not purport to address all of the
4.1.1 The control module typically will house the detector
safety concerns, if any, associated with its use. It is the
electronics that monitor or control, or both, the solvent flow,
responsibility of the user of this standard to establish appro-
reaction temperatures, and the conductivity detector cell. It can
priate safety and health practices and determine the applica-
be functionally independent of the gas chromatography or, in
bility of regulatory limitations prior to use.
some varieties, designed into the functional framework of the
2. Referenced Documents gas chromatograph. However, the reactor and cell assemblies
are designed for specific models of gas chromatographs so it is
2.1 ASTM Standards:
2 important the proper components be assembled on the appro-
E 260 Practice for Packed Column Gas Chromatography
priate chromatographic equipment.
E 355 Practice for Gas Chromatography Terms and Rela-
2
4.2 Fig. 2 is a block diagram representation of the GC/
tionships
ELCD system. The electrolytic conductivity detector detects
3. Significance and Use compounds by pyrolyzing those compounds in a heated nickel
catalyst (housed in the reactor), removing interfering reaction
3.1 Although it is possible to observe and measure each of
products with a scrubber (if needed), dissolving the reaction
the several characteristics of the ELCD under different and
products in a suitable solvent, and measuring the change in
electrical conductivity using a conductivity detector cell. Other
1
This practice is under the jurisdiction of ASTM Committee E13 on Molecular
suitable non-catalystic reaction tubes can be used for more
Spectroscopy and is the direct responsibility of Subcommittee E13.19 on Chroma-
selective response characteristics. Using the conditions set
tography.
forth in this practice, halogen (Cl, Br, I, F) compounds,
Current edition approved March 15, 1995. Published July 1995.
2
Annual Book of ASTM Standards, Vol 14.02.
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