ASTM E1151-93(2019)
(Practice)Standard Practice for Ion Chromatography Terms and Relationships
Standard Practice for Ion Chromatography Terms and Relationships
ABSTRACT
This practice deals primarily with identifying the terms and relationships of those techniques that use ion exchange chromatography to separate mixtures and a conductivity detector to detect the separated components. However, most of the terms should also apply to ion chromatographic techniques that employ other separation and detection mechanisms. The apparatus to be used in the chromatography shall consist of syringe pumps, reciprocating pumps, pneumatic pumps, septum injectors, valve injectors, precolumns, concentrator columns, guard columns, separating columns, suppressor columns, conductivity suppressors, membrane suppressors, micromembrane suppressor, bulk property detectors, and solute property detectors. Chemical reagents to be used in the chemical analysis shall be of four kinds: mobile phase, stationary phase, solid support, and column packing materials. The stationary phase has two types which are the liquid phase and interactive solid phase material. Totally porous packing and pellicular packing are the two types of column packing materials.
SCOPE
1.1 This practice deals primarily with identifying the terms and relationships of those techniques that use ion exchange chromatography to separate mixtures and a conductivity detector to detect the separated components. However, most of the terms should also apply to ion chromatographic techniques that employ other separation and detection mechanisms.
1.2 Because ion chromatography is a liquid chromatographic technique, this practice uses, whenever possible the terms and relationships identified in Practice E682.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1151 − 93 (Reapproved 2019)
Standard Practice for
Ion Chromatography Terms and Relationships
This standard is issued under the fixed designation E1151; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ionic or ionizable compounds. Of the many useful separation
and detection schemes, those most widely used have been the
1.1 This practice deals primarily with identifying the terms
two techniques described in 3.2 and 3.3 in which ion exchange
and relationships of those techniques that use ion exchange
separation is combined with conductimetric detection. By
chromatographytoseparatemixturesandaconductivitydetec-
describing only these two techniques, this practice does not
tor to detect the separated components. However, most of the
mean to imply that IC is tied only to ion exchange chroma-
termsshouldalsoapplytoionchromatographictechniquesthat
tography or conductimetric detection.
employ other separation and detection mechanisms.
3.2 Chemically Suppressed Ion Chromatography, (Dual
1.2 Because ion chromatography is a liquid chromato-
Column Ion Chromatography)—Inthistechnique,samplecom-
graphic technique, this practice uses, whenever possible the
ponents are separated on a low capacity ion exchanger and
terms and relationships identified in Practice E682.
detected conductimetrically. Detection of the analyte ions is
1.3 The values stated in SI units are to be regarded as
enhanced by selectively suppressing the conductivity of the
standard. No other units of measurement are included in this
mobile phase through post separation ion exchange reactions.
standard.
3.3 Single Column Ion Chromatography, (Electronically
1.4 This standard does not purport to address all of the
Suppressed Ion Chromatography)—In this technique sample
safety problems, if any, associated with its use. It is the
componentsareseparatedonalowcapacityionexchangerand
responsibility of the user of this standard to establish appro-
detected conductimetrically. Generally, lower capacity ion
priate safety, health, and environmental practices and deter-
exchangers are used with electronic suppression than with
mine the applicability of regulatory limitations prior to use.
chemical suppression. Mobile phases with ionic equivalent
1.5 This international standard was developed in accor-
conductancesignificantlydifferentfromthatofthesampleions
dance with internationally recognized principles on standard-
andalowelectrolyticconductivityareused,permittinganalyte
ization established in the Decision on Principles for the
ion detection with only electronic suppression of the baseline
Development of International Standards, Guides and Recom-
conductivity signal.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Apparatus
2. Referenced Documents
4.1 Pumps—Any of various machines that deliver the mo-
2.1 ASTM Standards:
bile phase at a controlled flow rate through the chromato-
E682Practice for Liquid Chromatography Terms and Rela-
graphic system.
tionships
4.1.1 Syringe Pumps, having a piston that advances at a
controlled rate within a cylinder to displace the mobile phase.
3. Descriptions of Techniques
4.1.2 Reciprocating Pumps, having one or more chambers
3.1 Ion Chromatography, (IC)—a general term for several
from which mobile phase is displaced by reciprocating pis-
liquid column chromatographic techniques for the analysis of
ton(s)ordiaphragm(s).Thechambervolumeisnormallysmall
compared to the volume of the column.
This practice is under the jurisdiction ofASTM Committee E13 on Molecular
4.1.3 Pneumatic Pumps, employing a gas to displace the
Spectroscopy and Separation Science and is the direct responsibility of Subcom-
mittee E13.19 on Separation Science.
mobile phase either directly from a pressurized container or
Current edition approved Dec. 1, 2019. Published December 2019. Originally
indirectly through a piston or collapsible container. The vol-
approved in 1993. Last previous edition approved in 2011 as E1151–93 (2011).
ume within these pumps is normally large as compared to the
DOI: 10.1520/E1151–93R19.
volume of the column.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.2 Sample Inlet Systems, devices for introducing samples
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. into the column.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1151 − 93 (2019)
4.2.1 Septum Injectors—The sample contained in a syringe pressure, causing intimate contact between screens and mem-
isintroduceddirectlyintothepressurizedflowingmobilephase branes. Mobile phase passes through a hole in the upper
by piercing an elastomeric barrier with a needle attached to a regenerant screen and membrane. It enters the screen-filled
syringe. The syringe is exposed to pressure and defines the mobile phase chamber and passes through it. It then exits
sample volume. through a second set of holes in the upper membrane and
4.2.2 Valve Injectors—The sample contained in a syringe regenerant screen. The regenerant flows countercurrent to the
(or contained in a sample vial) is injected into (or drawn into) mobile phase through the screen-filled regenerant chamber.
an ambient-pressure chamber through which the pressurized
4.5 Detectors—Devices that respond to the presence of
flowing mobile phase is subsequently diverted, after sealing
eluted sample components. Detectors may be divided either
against ambient pressure. The displacement is by means of
according to the type of measurement or the principle of
rotary or sliding motion. The chamber is a section (loop) of
detection.
tubing or an internal chamber.The chamber can be completely
4.5.1 Bulk Property Detectors, measuring the change in a
filled, in which case the chamber volume defines the sample
physical property of the liquid phase exiting the column. Thus
volume, or it can be partially filled, in which case the syringe
a change in the refractive index, conductivity, or dielectric
calibration marks define the sample volume.
constant of a mobile phase can indicate the presence of eluting
sample components. Conductimetric parameters, symbols,
4.3 Columns, tubes, containing a stationary phase and
through which the mobile phase can flow. units and definitions are given in Appendix X1.
4.5.2 Solute Property Detectors, measuring the physical or
4.3.1 Precolumns,positionedbeforethesampleinletsystem
and used to condition the mobile phase. chemical characteristics of eluting sample components. Thus,
light absorption (ultraviolet, visible, infrared), fluorescence,
4.3.2 Concentrator Columns, installed in place of the
sample chamber of a valve injector and used to concentrate and polarography are examples of detectors capable of re-
sponding in such a manner.
selected sample components.
4.3.3 Guard Columns, positioned between the sample inlet
5. Reagents
system and the separating columns and used to protect the
separator column from harmful sample components.
5.1 Mobile Phase—Liquid used to sweep or elute the
4.3.4 Separating Columns, positioned after the sample inlet
sample components through the chromatographic system. It
system and the guard column and used to separate the sample
mayconsistofasinglecomponentoramixtureofcomponents.
components.
5.2 Stationary Phase—Active immobile material within the
4.3.5 Suppressor Columns, positioned after the separating
column that delays the passage of sample components by one
column and a type of post column reactor where the conduc-
of a number of processes or their combination. Inert materials
tivity of the mobile phase is selectively reduced to enhance
that merely provide physical support for the stationary phase
sample detection.
are not part of the stationary phase. The following are three
4.4 Postcolumn Reactors, reaction systems in which the
types of stationary phase:
effluent from the separating columns is chemically or physi-
5.2.1 Liquid Phase—A stationary phase that has been
cally treated to enhance the detectability of the sample com-
sorbed (but not covalently bonded) to a solid support. Differ-
ponents.
encesinthesolubilitiesofthesamplecomponentsintheliquid
4.4.1 Conductivity Suppressors, post column reactors in
and mobile phase constitute the basis for their separation.
which the conductivity of the mobile phase is reduced through
5.2.2 Interactive Solid—Astationary phase that comprises a
reactions with ion exchangers. Conductivity suppressors are
relatively homogeneous surface on which the sample compo-
differentiated by their type (cationic or anionic), by their form
nents sorb and desorb effecting a separation. Examples are
+ +
(H ,Na , etc.), and by their method of regeneration (batch or
silica, alumina, graphite, and ion exchangers. In ion chroma-
continuous). tography the interactive material is usually an ion exchanger
4.4.2 Suppressor Columns—Tubular reactors packed with that has ionic groups that are either ionized or capable of
ionexchangers.Suppressorcolumnsrequirebatchregeneration dissociation into fixed ions and mobile counter-ions. Mobile
when the breakthrough capacity of the column is exceeded.
ionic species in an ion exchanger with a charge of the same
4.4.3 Membrane Suppressors—Reactors made from tubular sign as the fixed ions are termed “co-ions.” An ion exchanger
shaped ion exchange membranes. On the inside of the tube with cations as counter-ions is termed a “cation exchanger,”
flows the mobile phase; a regenerative solution surrounds the and an ion exchanger with anions as counter-ions is termed an
tube. These membrane suppressors can be in the form of an “anion exchanger.” The ionic form of an ion exchanger is
opened tube, hollow fiber suppressors, or a flattened tube for determinedbythecounter-ion,forexample,ifthecounter-ions
higher capacity. Tubular membranes can be packed with inert arehydrogenionsthenthecationexchangerisintheacidform
materials to reduce band broadening. or hydrogen form, or if the counter-ions are hydroxide ions
4.4.4 Micromembrane Suppressor—Reactors made from thentheanionexchangerisinthebaseformorhydroxideform.
two sizes of ion-exchange screen.Afine screen is used for the Ionicgroupscanbecovalentlybondedtoorganicpolymers(for
mobile phase chamber and a coarse screen is used for the example, styrene/divinylbenzene) or an inorganic material (for
regenerant chambers. The mobile phase screen is sandwiched example, silica gel). Ion exchange parameters, symbols, units
between ion-exchange membranes, and on either side of each and definitions are given in Appendix X2. Separation mecha-
membrane is a regenerant screen. The stack is laminated by nisms on ion exchangers are described in Appendix X3.
E1151 − 93 (2019)
5.2.3 Bonded Phase—A stationary phase that comprises a 6.6 Peak Height (EB in Fig. X1.1)—Distance measured in
chemical (or chemicals) that has been covalently attached to a the direction of detector response, from the peak base to peak
solid support. The sample components sorb onto and off the maximum.
bonded phase differentially to effect separation. Octadecylsilyl
6.7 Peak Widths—Represent retention dimensions parallel
groups bonded to silica represent a typical example for a
to the baseline. Peak width at base or base width, (KL in Fig.
bonded phase.
X1.1) is the retention dimension of the peak base intercepted
5.3 Solid Support—Inert material to which the stationary by the tangents drawn to the inflection points on both sides of
the peak. Peak width at half height, (HJ in Fig. X1.1) is the
phase is sorbed (liquid phases) or covalently attached (bonded
phases).Itholdsthestationaryphaseincontactwiththemobile retention dimension drawn at 50% of peak height parallel to
the peak base. The peak width at inflection points, (FG in Fig.
phase.
X1.1), is the retention dimension drawn at the inflection points
5.4 Column Packing—The column packing consists of all
(=60.7% of peak height) parallel to the peak base.
the material used to fill packed columns. The two types are as
follows:
7. Retention Parameters, Symbols, and Units
5.4.1 Totally Porous Packing—One where the stationary
7.1 Retention parameters, symbols, units, and their defini-
phase is found throughout each porous particle.
tions or relationship to other parameters are listed in Table
5.4.2 Pellicular Packing—Onewherethestationaryphaseis
X3.1.
found only on the porous outer shell of the otherwise imper-
NOTE 1—The adjusted retention time, capacity ratio, number of
meableparticle.Surfaceagglomeratedpackingsareconsidered
theoretical plates, and relative retention times are exactly true only in an
to be a type of pellicular packing.
isocratic, constant-flow system yielding perfectly Gaussian peak shapes.
7.2 Fig.X1.1canbeusedtoillustratesomeofthefollowing
6. Readout
most common parameters measured from chromatograms:
6.1 Chromatogram—Graphic representation of the detector
Retention time of unretained component, t = OA
M
response versus retention time or retention volume as the
Retention time, t = OB
R
sample components elute from the column(s) and through the
Adjusted retention time, t = AB
R
detector. An idealized chromatogram of an unretained and a
Capacity factor, k' = (OB − OA) ⁄OA
retained component is shown in Fig. X1.1.
Peak width at base, w = KL
b
6.2 Baseline—Portion of a chromatogram recording the
Peak width at half height, w = HJ
h
detector response when only the mobile phase emerges from
Peak width at inflection points,= FG =0.607(EB)
the column.
Number of theoretical plates, N=16[(OB)/
2 2
(KL)] =5.54[(OB)/(HJ)]
6.3 Peak—Portion of a chromatogram recording detector
Relative retention, r (Note 2)=(AB) /(AB)
response when a single component, or two or more unresolved i s
Peak resolution, R (Note 2 and Note 3)=2[(OB) −(OB)
s j i
components, elute from the column.
]/(KL) +(KL) . (OB) −(OB) /(KL)
i j j i j
6.4 Peak Base (CD in Fig. X1.1)—Interpolation of the
NOTE2—Subscripts i, j,and srefertosomepeak,afollowingpeak,and
baseline between the extremities of a peak.
a reference peak (standard), respectively.
6.5 Peak Area (CHFEGJD in Fig. X1.1)—Area enclosed
NOTE 3—The second fraction may be used if peak resolution of two
between the peak and the peak base.
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