A room temperature photochemically-induced fluorescence (RTPF) method
is proposed for the quantitative analysis of seven widely-used chlorop
henoxyacid herbicides. The influence of organic solvent, pH (in aqueou
s solutions), methanol percentage, and UV irradiation time on the exci
tation and emission wavelengths and fluorescence intensity was investi
gated. It was found that the largest fluorescence signals were obtaine
d in a mixture of methanol and pH 5 buffer (50/50, v/v), while organic
solvents and water produced generally lower signals. The tri- and bic
hlorinated phenoxyacid herbicides were photolysed significantly more s
lowly than the monochlorinated derivatives, and the derivatives of 2-p
ropionic acid were photodegraded more quickly than the corresponding d
erivatives of acetic and butyric acid. Selected UV irradiation times w
ere found to be 15 min for all herbicides under study. Linear calibrat
ion graphs were established. over about one to two orders of magnitude
in the interval 0.1-10 mu g ml(-1). The RTPF limits of detection were
between 36 ng ml(-1) and 179 ng ml(-1), according to the compound. An
alytical application of RTPF to river water samples containing chlorop
henoxyacid herbicides is discussed.