Electroanalysis with Carbon Paste–Based Electrodes, Sensors, and Detectors - Electroanalysis with Carbon Paste Electrodes - page 194

carbon.paste.biosensors.containing.salicylate.hydrolase,.which.releases.catechol.that.can.subse-
quently.be.oxidized.to.the.corresponding.quinone,.either.directly.or.via.Meldola.blue.as.mediator.
[1174,2694].
8.4.3 a Mino C oMpounds
8.4.3.1 Amides and Amines
Table. 8.17. comprises. analytical. methods. for. the. determination. of. amines. with. carbon. paste.
electrodes..Amines.with.neurotransmitter.function.will.be.discussed.in.Table.8.22.
Acrylamide. can. be. detected. indirectly. with. a. biosensor. containing. hemoglobin;. it. forms. an.
adduct. with. the. biological. recognition. element. and. decreases. its. reduction. current. [2420].. Cu(I).
oxide.can.be.used.as.a.catalyst.for.the.oxidation.of.amines.in.alkaline.medium,.similar.to.alcohols.
[1225]..The.principle.of.formation.of.a.Schiff.base.for.the.detection.of.aldehydes.[1021].can.be.also.
applied.to.amines.when.using.aldehyde.pentacyano-Fe(II).complexes;.the.Schiff.base.is.irreversibly.
oxidized.at.around.0.9.V.vs..SCE.[1743]..Co(II)-phthalocyanine.can.oxidize.amines.and.ephedrines.
in.alkaline.medium.via.Co(III).[902].
Synthetic.and.biogenic.amines.can.be.oxidized.by.amine.oxidase.either.in.puriied.form.[2695].
or.in.pea.seedling.tissue.[274];.the.intermediate.H 2 O 2 .is.detected.either.via.direct.oxidation.or.with.
HRP.as.a.mediator..Aniline.can.be.preconcentrated.at.sepiolite-modiied.carbon.paste.electrodes.
and.determined.in.beverages.without.need.to.prior.isolation.[2424]..Benzocaine.and.lidocaine.react.
chemically.with. p -chloranil.and.decrease.its.electrochemical.response.[1507].
Monoamine. oxidase. (MAO). can. oxidize. benzyl. amine. and. can. be. exploited. to. determine. the.
analyte.in.mouthwashes.[1167]..Biogenic.amines.are.usually.freshness.indicators.of.ish.or.meat..
They.can.be.detected.via.simultaneous.monitoring.of.their.oxidation.by.different.phthalocyanine-
modiied.CPEs.and.chemometric.evaluation.[2696]..Other.possibilities.involve.HRP.[2697],.carbon.
nanotubes.[2698],.amine.oxidase.with.HRP.on.sepharose.and.ferrocene.[589],.or.speciic.oxidases.
for.the.individual.amines.(sarcosine,.putrescine,.and.cadaverine)..Such.types.of.sensors.are.often.
designed.as.thick.ilm.sensors.(screen-printed.electrodes)..Histamine.can.be.detected.with.amine.
dehydrogenase.and.ferrocene.[2699].
Phenylethylamine.and.tyramine.can.be.catalytically.oxidized.with.CNT.[2700],.penicillamine.
and.tryptophan.with.quinizarine.on.TiO 2 .nanoparticles.[1880]..Oat.seedling.tissue.contains.poly-
amine.oxidase.and.peroxidase;.it.can.be.used.in.biosensors.for.polyamines.which.are.detected.via.
released.hydrogen.peroxide.[864].
Aromatic.amines.and.cancerogens.can.be.determined.by.adsorptive.anodic.stripping.with.CPEs.
modiied.with.cyclodextrins.and.direct.electrochemical.oxidation.[726,1413].
A.biosensor.for.urea.was.designed.with.urease.and.glutamate.dehydrogenase.[2701],.when.the.
respective.ammonium.ions.are.indirectly.detected.via.the.decrease.of.the.NADH.response.which.is.
consumed.by.the.dehydrogenase.to.form.glutamate.from.ketoglutarate.
8.4.3.2 Amino Acids
Amino. acids. were. frequently. the. subject. of. studies. with. carbon. paste. electrodes.. The. majority.
deal.with.voltammetric.and.amperometric.investigations,.although.potentiometric.detection.is.also.
possible.
In.amperometry,.detection.may.proceed.either.via.the.oxidation.of.the.amino-moiety.or.via.the.
chemical.and/or.electrochemical.reactivity.of.a.structural.element.of.the.compound.. N -acetyl.cyste-
ine.is.a.mucolytic.agent.and.is.also.used.as.a.food.supplement..It.can.be.determined.with.catalysts,.
such. as. caffeic. acid. [2702],. iron. oxide-Co(III)-hexacyanoferrate. core-shell. nanoparticles. [983],.
Co(III)-salophen.in.combination.with.carbon.nanotubes.[403],.or.methylphenothiazine.[2703].
Many.amino.acids.can.be.electrocatalytically.oxidized.by.copper.micro-.and.nanoparticles.and.
powder.[963,966,2704,2705],.Cu(I)-oxide.[401,556,1225,2706].and.various.other.oxides.[556,1223],.
usually. in. strongly. alkaline. media;. Cu(II)-cyclohexal-butyrate. can. be. used. as. well. [1607]..