Biology Reference
In-Depth Information
11.5.2
Solid Electrodes
There are many types of solid electrodes which are used for the
determination of purine nucleobases, their derivatives, and ODNs
containing purines in the presence of Cu(II). The glassy carbon
electrode(GCE)wasusedfortheelectrochemicalanodicstrippingof
adenine and guanine in Cu(II) solution [65]. It was found that Cu(II)
can be reduced to Cu(I) and the generated Cu(I) reacts with A and G
to accumulate on the GCE as an insoluble compound. Reoxidation of
Cu(I) to Cu(II) at positive potentials gives a large oxidation current
forthebase.Thesameelectrodewasusedforanultra-traceassayof
some derivatives of nucleic acid bases in Cu(II) solution. Promising
results were obtained also for xanthine determination [66]. The
coppersolidamalgamelectrodeissuitableforasensitiveanalysisof
A at very low concentrations. Compared to HMDE, the voltammetric
peak resulting from reduction of the Cu(I)-adenine complex with
theincreasingconcentrationofAshiftedtomorenegativepotentials,
indicating the adsorption of this complex on the electrode surface
[67].
Using a para
n-impregnated graphite electrode (PIGE) and
mercury-modified pyrolytic graphite electrode with basal orien-
tation (Hg-PGEb) Cu(I)-purine complex was studied by LSV in
connection with EVLS [68]. According to the elimination function
E4, the first cathodic peak corresponds to the reduction Cu(II)
+
e
−
→
Cu(I) with the possibility of fast disproportionation 2Cu(I)
→
Cu(II)
+
Cu(0). Anodic stripping voltammetry (ASV) on PIGE and
cathodic stripping voltammetry (CSV) on Hg-PGEb were carried out
at potentials where the reduction of copper ions took place and
Cu(I)-purine complexes were formed.
Electrochemical oxidations of aminopurines (adenine,
2-aminopurine, 2,6-diaminopurine) and their complexes with Cu(I)
were investigated on a pencil graphite electrode (PeGE) by LSV
and EVLS [69]. The anodic process of the sparingly soluble Cu(I)-
aminopurine complex, corresponding to the oxidation of Cu(I) to
Cu(II), takes place in the potential range between 0.4 and 0.5 V. At
more positive potentials, the aminopurines provide voltammetric
peaks resulting from the oxidation of the purine ring. The appro-
priate complex of Cu(I)-aminopurine has a synergic effect on the
