Carbon Pastes and Carbon Paste Electrodes - Electroanalysis with Carbon Paste Electrodes - page 20

Finally,.the.verge.of.two.millennia.saw.also.two.attempts.to.abandon.traditional.oils.in.favor.of.
alternatives,.namely,.(vii).castor.oil.(an.oily.substance.of.vegetable.nature.and.produced.from.cas-
tor.beans.of. Ricinus communis .sp.).applied.as.a.special.CPE.in.biological.analysis.[236].and.(viii).
vaseline.oil.(a.greasy.mass,.obtainable.by.industrial.fractionation.of.petroleum.jelly.and.having.the.
name.after.a.trademark.product).mixed.together.with.an.avocado.tissue.in.a.CP-based.biosensor.for.
clinical.analysis.[237].

2.1.3.6 New Types of Carbon Paste Binders
In. the. late. 1990s,. the. same. authors. published. two. related. papers. in. which. they. introduced. the.
called.“binder.paste”.(BP;.[238,239]),.based.on.a.polycationic.electrolyte.instead.of.traditional.oil..
Reportedly,.their.new.composite.material.offered.signiicant.improvements.compared.to.common.
carbon.paste.mixtures,.especially,.for.construction.of.biosensors.
Maybe. that. some. results. with. the. “binder. paste. electrodes”. (BPEs). were. also. motivating.
for. the. upcoming. activities. on. testing. (room. temperature). ionic. liquids,. (RT)ILs,. and. the.
.establishment.of.the.aforementioned,.brand.new.subarea.of.the.so-called.“carbon.ionic.liquid.
electrodes”. (CILEs). [84].. Whereas. the. BPEs. had. remained. as. more. or. less. a. single. attempt,.
the. CILE. conigurations. went. rapidly. to. the. fore. since. its. introduction. in. 2001. [125,126]..
And like the. equally. popular. “carbon. nanotubes. paste. electrodes”. (CNTPEs). [123,124],. also.
CILEs. represent. the. new. phenomenon. in. the. ield,. deserving. to. be. discussed. separately—in.
Section.2.2.3.3.

2.1.4 M ixing and p reparaTion oF C arbon p asTes

2.1.4.1 Carbon-to-Pasting Liquid Ratio
In.most.cases,.graphite.powder.and.pasting.liquid.are.mixed.together.in.quantities.chosen.accord-
ing.to.the.empiric.experience,.a.typical.“carbon-to-pasting-liquid.ratio”.varying.in.the.interval.of.
1.0.g:0.4-1.0.mL. [2,3,59,69,82,83,111].. Some. mixtures. contain. even. a. higher. percentage. of. liquid.
binder.since.the.resultant.ratio.of.the.two.main.components.depends.also.on.their.mutual.adherence.
[177,205]..Thus,.for.example,.1.g.of.graphite.may.“swallow”.up.to.7.mL.pasting.liquid,.which.is.the.
case.of.the.very.irst.paste.mixture.[1].

Note: . Appropriate.consistency.can.also.be.a.virtual.measure.of.how.to.adjust.the.optimal.carbon-
to-binder.ratio;.however,.one.should.be.aware.that.the.resultant.pastes.may.vary.quite.much—they.
can.be.inely.thick,.but.they.can.also.be.rather.hard.or.soft.or.even.sticky.[2,3,83,111]..In.this.con-
text,.it.has.to.be.pointed.out.that.especially.“carbon.pastes.of.the.new.generation,”.that.is,.the.new.
alternate.mixtures,.may.form.the.masses.with.atypical.consistency..These.features.are.due.to.spe-
ciic.surface.characteristics.of.new.carbons,.as.well.as.often.very.tight.adhesiveness.of.some.highly.
lipophilic.binders,.both.contributing.to.the.resultant.compactness.of.such.pastes..Here.for.example,.
one.can.remember.again.“muddy”.and.almost.luidic.mixtures.made.of.some.GC-powders.(such.
as. Sigradur. with. pretreated. surface. of. carbon. particles. [96,192]). or,. oppositely,. extremely. hard,.
dificult-to-handle,. and. notably. deep. black. masses. obtained. by. homogenizing. Nujol. with. higher.
percentages.of.multiwalled.CNTs.[229].

Thus,.it.can.be.recommended.to.seek.and.ind.a.suitable.ratio.of.both.pasting.constituents.experi-
mentally—for.each.individual.carbon.paste.mixture.intended.to.be.prepared.and.used..Such.evalua-
tion.can.advantageously.be.accomplished.by.means.of.special.testing.measurements.with.a.series.of.
CPEs.[176,177],.where.the.corresponding.carbon.paste.mixtures.have.been.prepared.from.identical.
components. and. differed. solely. from. the. ratio. chosen.. During. this. examination,. one. can. utilize.
a. number. of. special. tests. with. standard. inorganic. and. organic. electrode. systems;. a. comparison.
with. measurements. carried. out. by. using. traditional. solid. electrodes. like. GCE. or. Pt-disc. is. also.
advantageous.