Electrochemical Investigation with Carbon Paste Electrodes and Sensors - Electroanalysis with Carbon Paste Electrodes - page 165

monitored.during.the.assay.has.conirmed.that.rats.are.nocturnal.animals,.showing.a.signiicantly.
higher.level.of.motor.activity.in.the.darkness.
Regarding.the.detection.as.such,.this.experiment.has.also.demonstrated.the.stability.of.the.μE.used.
and.its.proper.function.inside.the.brain.[605]..Especially.the.long-term.stability.of.CPm/μEs,.which.
may.attain—under.favorable.circumstances—up.to.several.months.of.permanent.use.[601],.is.quoted.
to.be.maybe.the.most.valuable.feature.of.CPEs.in.connection.with.IVV.and.related.applications.
As.implied.by.the.relatively.frequent.term.“brain.electrochemistry”.[50],.a.great.majority.of.mea-
surements.required—either.acute.(short-time).or.chronic.(long-term).[2129]—implantation.of.a.CPm/μE.
into.the.respective.parts.of.the.brain.of.anesthetized.animals,.although.experimentation.without.anes-
thesia.is.reportedly.also.feasible.[2126,2140]..Mostly,.the.laboratory.animals.examined.are.rats.(e.g.,.
[598,1025,2152]),.occasionally.monkeys.[600,2128],.cats.[2128],.or.even.ish.[37]..Other.parts.of.the.
body.for.implantation.were.also.reported.(e.g.,.spinal.cord.[600].or.rat.tail.[396])..In.contrast.to.this.
variety,.“nonanimal”.applications.of.implanted.sensors.are.very.rare.and,.in.fact,.represented.to.date.
by.a.lone.study.with.a.CNTPmE.penetrating.the.skin.of.an.orange.or.an.apple.[409].

7.3.3 s urVey oF a ppliCaTions and s oMe p rospeCTs
In.the.individual.reports,.a.logical.domain.of. in vivo .measurements.is.the.monitoring.of.biologically.
important.compounds.(BIC),.and.all.typical.applications.are.presented.in.detail.in.Chapter.8—with.
the.typical.experimental.data.gathered.in.Table.8.27.
Here,.only.an.informative.survey.is.given,.specifying.mainly.which.substances.are.of.interest..One.
can.start.with.catechols.and.catecholamines,.that.is,.dopamine.(DA;.e.g.,.[48,376,602,605,1022,1108,.
2130,2137,2153]).plus.its.metabolite.homovanillic.acid.(HVA;.[2119,2151]).and.related.l-DOPA.[2119].or.
6-OHDA.(6-hydroxydopamine.or.oxidopamine.[49]),.and.norepinephrine.(syn..noradrenaline.[2117,2120]).
with. their. interfering. “companions”. ascorbic. acid. or. ascorbate. (AA;. [597,1642,2135,2142,2151]),. uric.
acid.(UA;.[2136,2141,2145,2151]),.or.5-HIAA.(hydroxy-indoleacetic.acid.[2141]).
The.list.continues.with.serotonin.(5-hydroxytryptamine,.5-HT;.[593,2146,2147]),.glutamate.(amino.
acid.[2152]),.choline.[2152],.glucose.[611,1774,2152],.and.some.pharmaceuticals.such.as. Acetaminophen .
(syn.. Paracetamol .[600]),. Flunitrazepam .(a.benzodiazepine.anxiolytic.[2139]).with.hypnotics.and.abuse.
drugs.(d- Amphetamine .[603,2149]),.caffeine.[430],.cocaine.[2132],.or.morphine.[1023]),.the.latter.two.
studied.via.their.pathway.in.the.brain.and.their.role.in.the.metabolism.of.principal.neurotransmitters.
The. list. of. substances. and. species. detectable. in vivo . can. be. completed. by. quoting. the. real-
time.monitoring.of.oxygen.[2142,2145,2154],.or.recently.introduced.environmental.monitoring.with.
electrodes.of.the.new.generation,.CNTPm/μEs.(surveyed.in.Section.2.2.3),.so.far.applied.to.some.
bioaccumulative. pollutants,. namely,. insecticide. “EPN”. (i.e.,. ethyl- O-p -nitrophenyl-phenyl. phos-
phonothionate.[409]).and.two.heavy.metal.ions:.Cd 2+ .[377].and.Cu 2+ .[396]..Within.the.area.of.
in vivo .measurements,.these.less.typical.applications.are.important.with.respect.to.future.prospects,.
showing.that.there.are.other.promising.routes.for.investigations.with.implanted.electrodes.that.may.
lead.to.a.wider.diversity.of.the.ield,.which.is.still.anchored.mainly.in.neuroscience.

7.4 SPECIAL STUDIES WITH CARBON PASTES

7.4.1 r ole oF M inor r esearCh
Among.the.“remaining”.research.activities.with.carbon.pastes,.there.are.classiied. special studies .
whose.impact.on.the.ield.is.ambivalent.as.having.crossed.both.large.categories,.thus.allowing.one.to.
classify.such.measurements.additionally..By.taking.into.account.the.overall.abundance,.they.surely.
fall.into.a. minor research ;.nevertheless,.their.outputs.and.achievements.cannot.be.considered.to.be.
of.marginal.importance..On.the.contrary,.numerous.results.manifest.pretty.well.some.less-obvious.
features. of. CPEs. and. the. carbon. pastes,. which. is. a. suficient. reason. for. the. statement. that. even.
minor.and.specially.focused.investigations.deserve.adequate.attention.