ASTM E1511-93(2005)
(Practice)Standard Practice for Testing Conductivity Detectors Used in Liquid and Ion Chromatography
Standard Practice for Testing Conductivity Detectors Used in Liquid and Ion Chromatography
SIGNIFICANCE AND USE
This practice is intended to describe the performance of a conductivity detector independent of the chromatographic system in terms that the analyst can use to predict overall system performance when the detector is coupled to the column and other chromatography system components.
Although it is possible to observe each of the several characteristics of a detector under different and unique conditions, it is the intent of this practice that a complete set of detector specifications should be obtained at the same operating conditions, including the setup used for testing, flow rates, and temperatures. It should be noted that to specify a detector’capability completely, its performance should be measured at several sets of conditions within the useful range of the detector. The terms and tests described in this practice are sufficiently general so that they may be used at whatever conditions may be chosen for other reasons.
SCOPE
1.1 This practice covers the testing of the performance of conductivity detectors used as the detection component of a liquid or ion chromatography system.
1.2 The values stated in SI units are to be regarded as the standard.
General Information
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Standards Content (Sample)
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Designation:E1511–93 (Reapproved 2005)
Standard Practice for
Testing Conductivity Detectors Used in Liquid and Ion
1
Chromatography
This standard is issued under the fixed designation E1511; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope of the solution is defined to be independent of electrode and
cell dimensions. Specifically,
1.1 This practice covers the testing of the performance of
conductivity detectors used as the detection component of a 1
k5 G (1)
liquid or ion chromatography system. A
1.2 The values stated in SI units are to be regarded as the
where:
standard.
1 = the distance between two planer disk electrodes, and
A = the electrode’s surface area.
2. Referenced Documents
3.2.3.1 Discussion—In liquid and ion chromatography, cell
2
2.1 ASTM Standards:
dimensions are commonly measured in centimetres, so the
E1151 Practice for Ion Chromatography Terms and Rela-
units of k are S/cm. (Alternatively, the SI units of S/m may be
tionships
used. S/m = 100 S/cm.)
3.2.4 drift—the average slope of the noise envelope ex-
3. Terminology
pressed in nano siemens per centimetre per hour as measured
3.1 See Practice E1151.
over a period of 1 h.
3.2 Definitions:
3.2.5 equivalent conductivity—of an ionic solute, the con-
3.2.1 cell constant—the cell constant (K) of a conductivity
tribution of the solute to the total conductivity of the solution,
cell is equal to 1/A,so k =GK.
measured in microsiemens per centimetre, divided by its
3.2.1.1 Discussion—If the cell constant of the flow-through
concentration in milliequivalents/litre.
cell used is equal to one, then the conductivity equals the
3.2.6 flow dependence rate—the change in measured con-
conductance. Although the cell constant is often specified for
ductivity as a function of flow rate.
conductivity detectors, there is little practical value in knowing
3.2.7 limiting equivalent conductivity—of an ionic solute,
the constant as long as the detector is properly calibrated for
its equivalent conductivity extrapolated to infinite dilution.
conductivity.
3.2.8 linear range—of a conductivity detector for a given
3.2.2 conductance—the conductance (G) of a solution is the
solute in a specific solvent, the concentration range of solute
inverse of the resistance measured between two electrodes in a
for which the detector response factor is within 5 % of the
cell, expressed in units of siemens (S), equal to inverse ohms.
response factor in the middle of the range as determined from
3.2.2.1 Discussion—The term resistance refers specifically
the linearity plot specified in Section 11.
to the dc resistance to ionic current, independent of the
3.2.8.1 Discussion—The lower limit may be limited by
capacitive reactance at the interfaces between the electrodes
noise, and the upper limit by deviation from linearity. (The
and the solution.
upper limit may instead be limited by the maximum full-scale
3.2.3 conductivity—since the conductance is dependent on
deflection on the detector’s least sensitive output range.)
both the conductive properties of the solution and on the
3.2.9 long-term noise—the maximum amplitude in nano
dimensions of the electrodes and the cell, the conductivity (k)
siemenspercentimetreforallrandomvariationsofthedetector
output of frequencies between 2 and 60 cycles per hour.
1
This practice is under the jurisdiction of ASTM Committee E13 on Molecular
3.2.9.1 Discussion—Long-term noise represents noise that
Spectroscopy and Chromatography and is the direct responsibility of Subcommittee
can be mistaken for eluting peaks.
E13.19 on Chromatography.
3.2.10 minimum detectability—of a conductivity detector,
Current edition approved Feb. 1, 2005. Published March 2005. Originally
that concentration of solute in a specific solvent that corre-
approved in 1993. Last previous edition approved in 2000 as E1511 - 93(2000).
DOI: 10.1520/E1511-93R05.
sponds to twice the short-term noise.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.10.1 Discussion—Because of the difficulty of pumping
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
solvents through the chromatographic system without any
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. contamination of the solvents from the system, this quantity
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E1511–93 (2005)
can only be measured with solutes retained by a column. Since 5. Significance and Use
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