The electrochemical activity of poly(8-hydroxyquinoline)
(PHQ) in acid and alkaline media has been investigated
by use of differential pulse polarography
(DPP). The reduction peak height (Ip) of PHQ in universal
buffer solutions is not useful as an analytical signal, because
it is highly affected by hydrogen evolution in acid
media and appears as a small peak located at more negative
potential values in alkaline media. A new and highly
sensitive reduction peak (Ep=–0.45, pH 9.25) appears,
however, after addition of trace amounts of PHQ to
Cu(II), or vice versa. This reduction peak is a result of the
reduction of Cu(II) chelates in the PHQ–Cu(II) complex
and is highly promising for the trace determination of
PHQ at nanomolar and submicromolar levels. The response
current (Ip/μA) for the reduction peak of Cu(II)
chelates in a PHQ–Cu(II) matrix results in sensitivity to
the concentration of PHQ at least three orders of magnitude
higher than that for the reduction peak of PHQ alone
under the same conditions. The limit of detection is as low
as 5.264 ppsulating poly(vinyl alcohol) (PVA)
matrix has been investigated. Electroactive PHQ–Cu(II)
at a level of 0.685% could induce a current of approximately
240 nA in an insulating PVA matrix, suggesting
possible application for the preparation of a PHQ–Cu(II)–
PVA electroactive composite.
Keywords Differential pulse polarography ·
Poly(8-hydroxyquinoline) · Copper(II) determination ·
Poly(vinyl alcohol)