Instrumental Measurements with Carbon Paste Electrodes, Sensors, and Detectors - Electroanalysis with Carbon Paste Electrodes - page 135

•. Batch injection analysis (BIA) .is.operated.under.dynamic.conditions.[1948-1954],.where.
the.analyte.solution.is.injected.directly.onto.the.surface.of.the.sensor.in.a.wall-jet.conigu-
ration;. the. sensor. is.submerged. in. a. large.volume. of. solution.. A. transient. signal. occurs,.
similar. to. FIA,. due. to. the. stream. of. injected. analyte. solution. toward. the. electrode. and.
ensuing.dilution.in.the.bulk,.yielding.a.peak-shaped.signal.
. . . Manual. BIA. usually. yields. worse. reproducibility. than. FIA. due. to. variations. when.
injecting.the.solutions..Therefore,.automated.systems.[1948].or.capillary.injection.in.com-
bination.with.small-sized.electrodes.[1954].are.preferable..BIA.can.also.be.combined.with.
voltammetry.and.even.with.stripping.voltammetry.[1951,1953].
•. Liquid chromatography (HPLC) .offers.similarly.favorable.conditions.for.AD.employing.
often.the. glassy carbon electrode .( GCE ).in.the.detection.system..Carbon.paste.can.provide.
a.simple.alternative.particularly.if.the.CMCPE.variants.are.to.be.used.
•. Capillary (zone) electrophoresis, C(Z)E ,. is. a. relatively. new. method. of. employing. some.
microsized.CPEs.applicable.as.amperometric.detectors,.including.dual.conigurations.(see.
Sections.2.3.4.through.2.3.6.and.some.examples.in.Section.8.4).
With.AD,.the.peak.current,. i p ,.is.dependent.on.the.geometry.of.the.detector.electrode.
and.its.position.toward.the.solution.stream.
•. Wall-jet coniguration .is.a.special.arrangement.of.the.working.electrode.inside.a.detection.
cell,.where.the.electrode.surface.perpendicular.to.the.incoming.stream.of.the.carrier. i p .can.
be.approximated.by.the.limiting.current. i d .at.disk.electrodes.in.wall-jet.coniguration.and.
continuous.low.(Equation.6.19.according.to.[1955]):

*

3 4 / 2 3 / − 5 12 / − 1 2 /

i ≈ i = 1 43 . ⋅ n F R V ⋅ ⋅ ( ⋅ ) ⋅ D ⋅ v ⋅ a ⋅ C . (6.19)

p d f

.

. . where

R .is.the.radius.of.the.disk.electrode
V f .is.the.volume.low.rate.of.the.solution
v .is.the.viscosity.of.the.solution
a .is.the.diameter.of.the.jet.stream

Other. symbols. have. the. same. meaning. as. before.. For. some. other. conigurations,. see.
Table 6.1.[1915].

6.4 POTENTIOMETRY

6.4.1 d ireCT p oTenTioMeTry and p oTenTioMeTriC T iTraTions
(Equilibrium).potentiometry.is.another.common.electrochemical.technique.for.measurements.with.
carbon.paste-based.electrodes..It.can.be.estimated.that.(i).direct.potentiometry.and.(ii).potentio-
metric.titrations.are.both.on.the.third.rank.with.respect.to.the.abundance.of.their.use,.immediately.
after.voltammetry.and.amperometry..This.has.been.documented.in.a.wide.variety.of.publications.
mentioned. earlier. (e.g.,. [36,159,208,232,251,253,448,457,517,538,569,570,655,709,712]),. within.
this.section.(together.with.associated.citations.[178,1956-1976]),.as.well.as.later.in.Chapter.8.and.
throughout.the.table.surveys.
Regarding.direct.potentiometry,.the.respective.measurements.are.employed.to.complete.chemi-
cal. analyses. of. species. for. which. an. indicator. electrode. is. available.. The. technique. is. simple,.
requiring.only.a.comparison.of.the.voltage.developed.by.the.measuring.cell.(consisting.of.two.half-
cells—indicator.and.reference.electrodes).in.the.test.solution.with.its.voltage.when.immersed.in.a.