The diffusion of drugs residues in wastewaters and superficial waters as rivers and streams may constitute a problem for environment, with consequences on the ecosystem and also on the human health. In order to study the transformation pathways that drugs may undergo in the environment, such as photolysis, hydrolysis, oxido/reductive processes, we have photoinduced the degradation of some common drugs through an artificial irradiation system. Amiloride, an orally administered diuretic agent, has been studied for this purpose. It has been irradiated by a lamp simulating the solar light, using a 360 nm cut-off filter and by adopting TiO2 as a photocatalyst. Amiloride (m/z 230) disappearance and the identification and quantification of the degradation products as a function of the irradiation time have been performed by adopting an HPLC/HRMS spectrometer. Amiloride undergoes the complete degradation within half an hour of irradiation. The main products formed along with the amiloride photo-catalysed transformation are mainly hydroxylated and hydrolysis products. The amiloride transformation pathways proceed through: 1) dechlorination and hydroxylation of the heteroaromatic ring; 2) the detachment of the guanidinic moiety; 3) concerted loss of the amino groups and the guanidine; 4) cleavage of the heteroaromatic ring. The fate of nitrogen and chlorine atoms have been also monitored through a ion chromatograph. Chlorine is stoichiometrically released as chloride atom within the considered irradiation times, while nitrogen is only partially converted into NO3-, NH4+ions. It is due to the formation of guanidine, recognized to be hardly mineralized
HPLC/HRMS study of the photoinduced transformation products of diuretics: the case of amiloride
MASSOLINO, CRISTINA;MEDANA, Claudio;BAIOCCHI, Claudio;CALZA, Paola
2007-01-01
Abstract
The diffusion of drugs residues in wastewaters and superficial waters as rivers and streams may constitute a problem for environment, with consequences on the ecosystem and also on the human health. In order to study the transformation pathways that drugs may undergo in the environment, such as photolysis, hydrolysis, oxido/reductive processes, we have photoinduced the degradation of some common drugs through an artificial irradiation system. Amiloride, an orally administered diuretic agent, has been studied for this purpose. It has been irradiated by a lamp simulating the solar light, using a 360 nm cut-off filter and by adopting TiO2 as a photocatalyst. Amiloride (m/z 230) disappearance and the identification and quantification of the degradation products as a function of the irradiation time have been performed by adopting an HPLC/HRMS spectrometer. Amiloride undergoes the complete degradation within half an hour of irradiation. The main products formed along with the amiloride photo-catalysed transformation are mainly hydroxylated and hydrolysis products. The amiloride transformation pathways proceed through: 1) dechlorination and hydroxylation of the heteroaromatic ring; 2) the detachment of the guanidinic moiety; 3) concerted loss of the amino groups and the guanidine; 4) cleavage of the heteroaromatic ring. The fate of nitrogen and chlorine atoms have been also monitored through a ion chromatograph. Chlorine is stoichiometrically released as chloride atom within the considered irradiation times, while nitrogen is only partially converted into NO3-, NH4+ions. It is due to the formation of guanidine, recognized to be hardly mineralized
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