Entwicklung und Anwendung chemisch-analytischer Verfahren zur Bestimmung endokrin wirksamer Substanzen
- Development and application of analytical methods for determination of endocrine disrupting compounds
Stehmann, Angelika; Schröder, Horst Friedrich (Thesis advisor)
Aachen : Publikationsserver der RWTH Aachen University (2007)
Dissertation / PhD Thesis
Aachen, Techn. Hochsch., Diss., 2006
The aim of this work was to develop analytical methods for identification and quantification of endocrine disrupting compounds (EDCs) from matrices, which result during the waste water treatment process. Especially matrices like sewage sludge and sediments were investigated. From the abundance of the EDCs the xenoestrogens Nonylphenol, Bisphenol A and Octylphenol as well as the estrogens Estrone, 17beta-Estradiol, Estriol and 17alpha-Ethinylestradiol was selected. These substances possess a high environmental relevance. They will either manufacture in large quantities industrially or by biochemical degradation during the waste water treatment process or they are eliminated by humans. For influent and effluent samples a method, consisting enrichment at C18-solid phase material with following clean-up at silica gel and derivatisation by means of heptafluorbutyric acid anhydride, was developed. The detection of these endocrine disrupting compounds and the following identification and quantification took place by means of measure-spectrometric detection after previous separation by gas chromatography (GC-MS). Especially the influence of different derivatisation reagents on the detection limit was tested. The influence of different amounts of fluor in the derivatisation reagents on the sensitivity was examined with electron ionization or negative chemical ionization. The optimal derivatisation reagent was heptafluorbutyric acid anhydride. For the routine determination of the EDCs the positive electron ionization (EI(+)) was therefore used. The recovery of this optimized analytical method lay between 77 and 116% and the detection limits lay in the lower ng/L range, so that the method is suitable for the analysis of real waste water samples on EDCs. The characteristic of the determination from the solid matrices sewage sludge and/or sediment was the extraction by "accelerated solvent extraction" (ASE). This extraction is also known under "pressurized liquid extraction" (PLE). This extraction method was used not so much in the past for the complete range of the selected EDCs. The extraction became regarding temperature, pressure, used solvent and/or solvent mixture - after kind and quantity - as well as regarding the extraction time and amount of sample material optimized. The developed method is especially efficient regarding the extraction yield, i.e., the recovery is within the range of 82 to 116% for sewage sludge and form 74 to 104% for sediments. Compared with the frequently used Soxhlet extraction the developed ASE extraction is on the one hand substantially faster and used on the other hand smaller volumes of solvents. The following clean up of the sample extract took place according to the processing of aqueous samples, after the organic extract had been resuspended in high-purity water. The optimized analytical method for determination of EDCs in solid matrices was also used, in order to illustrate the load of the sediment of a lake with name "Volvi", lain in Greece, during the period of two years. This lake is proven by the Ramsar Convention on Wetlands as an internationally meaning humid area. Due to this protection the information about the load with endocrine disrupting compounds is of large interest. The results showed that the load in the investigation period had strongly decreased. At the beginning of the investigation the most potent steroids were detectable, at the last sampling date only bisphenol A was observed, this however in clearly smaller concentrations than at the beginning of the investigation. Now there are validated analytical methods available for the determination of the endocrine disrupting compounds Nonylphenol, Bisphenol A and Octylphenol, Estrone, 17beta-Estradiol, Estriol and 17alpha-Ethinylestradiol from liquid and solid matrices, i.e., from waste water, sewage sludge and sediments. They were already used routinely.