Introduction to Electrochemistry and Electroanalysis with Carbon Paste–Based Electrodes - Electroanalysis with Carbon Paste Electrodes - page 2

1.1.1 1958: T he V ery F irsT r eporT on C arbon p asTe e leCTrodes
As.already.noticed,.the.end.of.the.1950s.saw.an.unsuccessful.attempt.at.constructing.an.alternative.
to.Heyrovský's.dropping.mercury.electrode.for.anodic.oxidations.[1]..Instead,.the.electrochemists.
obtained.a.brand.new.electrode.material—carbon.paste—whose.potentialities.in.electrochemical.
research.and.applied.measurements.could.only.be.assumed.at.that.time..This.was.pretty.well.for-
mulated. by. Peter T. Kissinger ,. another. Adams's. student,. in. his. dedicated. proile. [5]:. “…. I. don't.
think.anyone.could.have.predicted.a.number.of.carbon.paste.publications.from.reading.the.very.irst.
carbon.paste.article.…”.(Herein,.we.can.add.that.this.number.is.currently.around.2500.scientiic.
publications,.increasing.by.20-30.new.items.each.month.)
The.irst.carbon.paste.was.a.mixture.of.1.g.carbon.powder.with.7.mL.bromoform,.whose.proper-
ties.were.demonstrated.on.the.oxidation.of.iodide.in.a.solution.of.1.×.10 −4 .M.I − .in.1.M.H 2 SO 4 ;.the.
second.paste.was.reportedly.tested.as.a.mixture.of.graphite.and.carbon.tetrachloride.[1]..In.retro-
spect,. these. pioneering. experiments. had. been. quite. atypical. for. research. activities. of. the. carbon.
paste.inventor.and.his.group.whose.domain.was.mainly.organic.electrochemistry.
1.1.2 1959-1963: p roposals oF C arbon p asTes ,
T heir C haraCTerizaTion , and i niTial a ppliCaTions
The. early. years. of. using. CPEs. can. be. classiied. as. the. “Era. of. Adams's. Group”. or. “Era. of. the.
Electrochemists.from.Kansas.University.(KU).”.At.that.time,.several.selected.types.of.carbon.pastes.
were.subjected.to.a.fundamental.characterization.in.anodic.and.cathodic.voltammetry.[8,9],.using.
both.inorganic.and.organic.compounds.as.model.species.or.systems..Of.interest.were.also.self-made.
carbon.paste.holders.applicable.in.several.different.electrode.conigurations.[10,11].
As.time.went.by,.the.initially.preferred.halogenated.liquids.were.replaced.by.less.harmful.and.
commercially.available.mineral.oils.such.as.Nujol ® ,.which.was.inally.recommended.as.the.pasting.
liquid.of.choice..(It.is.notable.that.this.substance.is.still.one.of.the.most.popular.binders.for.the.
preparation. of. carbon. pastes. and. its. use. is. being. regularly. reported. in. research. articles. until.
now. [7].). Satisfactory. experience. from. the. testing. measurements. with. CPEs. soon. initiated. their.
systematic.employment.in.investigations.of.the.electrode.behavior.of.various.substances,.predomi-
nantly. biologically. important. aromates. from. the. family. of. substituted. phenols,. aromatic. amines,.
and.aminophenols..The.results.of.these.studies.were.irst.summarized.in.Adams's.review.[2].and.
later,.in.more.detail,.in.the.aforementioned.textbook.[3]..Moreover,.after.a.lengthy.period.of.four.
decades,.these.invaluable.investigations.are.again.the.central.point.of.interest.within.this.topic—in.
Section.7.1.
Extensive.studies.of.both.anodic.oxidations.and.cathodic.reductions.of.organic.compounds.were.
typically.qualitative.in.nature,.and.therefore,.the.irst.quantitative.analysis.with.carbon.paste-based.
electrodes.can.be.attributed.to.Jacob's.simultaneous.determination.of.gold.and.silver.[12].who.was.
using.atypical.(bell-shaped).tubings.illed.with.carbon.paste..The.author.of.the.corresponding.pro-
cedure,.offering.the.limits.of.detections.at.the.nanomolar.level.despite.the.use.of.direct.voltammetry.
(i.e.,. without. accumulation. step),. is. also. an. early. user. of. CPEs. who. had. not. originated. from. the.
research.team.at.the.KU,.the.other.two.being.Davis.and.Everhart.[13].
1.1.3 1964, 1965: F irsT M odiFiCaTions oF C arbon p asTes
In.the.mid-1960s,.two.other.breaking.events.happened.in.Adams's.laboratories..First,.it.was.shown.
that. carbon. pastes. made. of. the. two. main. constituents. might. contain. another. component. and. the.
resultant.system.offered.new.attractive.applications.in.electrochemical.research.[14,15]..The.inten-
tion. of. such. an. approach. was. to. use. the. binary. nature. of. carbon. pastes. for. obtaining. a. simple.
approach.to.study.the.electrode.behavior.of.compounds.completely.insoluble.in.aqueous.solutions.
(see. also. the. foreword. to. this. topic).. Because. the. whole. concept. “bare. carbon. paste. +. substance.