The Photodegradation of Diazepam and its Human Metabolites in Water
type: CreativeWork
description: In recent years, the environmental occurrence, fate and effects of pharmaceuticals or pharmaceutically active compounds (PhACs) and their metabolites have received increased attention. PhACs have been detected in wastewater, river water, marine waters and even sewage sludge and soil. Since PhACs are developed with the intention of stimulating or inhibiting physiological responses, these findings have prompted concern over their environmental fate and potential adverse effects on nontarget ecological species. The major source of discharge of PhACs to the environment is through sewage treatment works (STWs) effluents and sludges. Although used in quantities similar to many agrochemicals and other organic micropollutants, PhACs are not required by legislation to undergo the same level of testing for possible environmental effects. Therefore, PhACs and their metabolites have been subject to many years of unrestricted emission to the environment. Typically, concentrations measured in municipal sewage treatment plant effluents are mg Lˉ¹, whilst those in the surface waters range from ng Lˉ¹ to µg Lˉ¹. The fate of PhACs in the aquatic environment is determined by both abiotic and biotic processes. Abiotic transformations in surface waters may occur via hydrolysis-and photolysis, with photolysis thought to be a significant factor in determining their environmental fate. In the present study, the anti-anxiety drug, diazepam (Valium®) along with its known human metabolites, nordiazepam, temazepam and oxazepam were selected for photodegradation studies. The photodegradability of each drug in distilled and natural waters was evaluated using a Suntest CPS Xenon arc lamp, selected to reproduce the spectral distribution of solar irradiation, with emphasis on the determination of degradation rate constants and half-lives under realistic environmental conditions. Solid phase extraction (SPE) methods were developed for extraction of these compounds from natural water samples and anal…
abstract: In recent years, the environmental occurrence, fate and effects of pharmaceuticals or pharmaceutically active compounds (PhACs) and their metabolites have received increased attention. PhACs have been detected in wastewater, river water, marine waters and even sewage sludge and soil. Since PhACs are developed with the intention of stimulating or inhibiting physiological responses, these findings have prompted concern over their environmental fate and potential adverse effects on nontarget ecological species. The major source of discharge of PhACs to the environment is through sewage treatment works (STWs) effluents and sludges. Although used in quantities similar to many agrochemicals and other organic micropollutants, PhACs are not required by legislation to undergo the same level of testing for possible environmental effects. Therefore, PhACs and their metabolites have been subject to many years of unrestricted emission to the environment. Typically, concentrations measured in municipal sewage treatment plant effluents are mg Lˉ¹, whilst those in the surface waters range from ng Lˉ¹ to µg Lˉ¹. The fate of PhACs in the aquatic environment is determined by both abiotic and biotic processes. Abiotic transformations in surface waters may occur via hydrolysis-and photolysis, with photolysis thought to be a significant factor in determining their environmental fate. In the present study, the anti-anxiety drug, diazepam (Valium®) along with its known human metabolites, nordiazepam, temazepam and oxazepam were selected for photodegradation studies. The photodegradability of each drug in distilled and natural waters was evaluated using a Suntest CPS Xenon arc lamp, selected to reproduce the spectral distribution of solar irradiation, with emphasis on the determination of degradation rate constants and half-lives under realistic environmental conditions. Solid phase extraction (SPE) methods were developed for extraction of these compounds from natural water samples and anal…
author: West, Charles Edward
language: eng
date published: 2007-01-01T08:00:00Z
date modified: 2026-07-24T03:49:07Z
provider: University of Plymouth
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Plymouth