At a chosen interval of irradiation
time, aliquots of the reaction mixture were withdrawn and
filtered with a membrane filter (0.1 "m). To determine 2-CP concentration,
the sample solutions were subsequently reacted with
4-aminoantipyrine at pH 7.9 ±0.1 in the presence of potassiumferricyanide
to form a coloured antipyrine dye. This dye was kept in
aqueous solution, and the absorbance was measured at 510 nmby a
Lambda 35 PerkinElmer UV–vis spectrometer [13]. The concentration
of 2-CP at each sampling time was designated as C. The reaction
period for all experiments in this work was 50 min unless otherwise
specified. For identification of intermediate products from
2-CP irradiated solutions after 50 min, the sample was analysed by
a Clarus 600 PerkinElmer gas chromatograph equipped with a mass
selective detector (Clarus 600T Mass Spectrometer). The GC column employed was a PE-1HT (0.25 mmi.d., 30 m) column (PerkinElmer)
with 0.1 mmfilm thickness. The GCMSoperating conditions and the
extraction procedure have been described elsewhere [14].