Micropollutants - Detection, Monitoring and Control. Micropoluentes - Detecção, Monitoramento e Controle

Transcription

1 1 Micropollutants - Detection, Monitoring and Control Micropoluentes - Detecção, Monitoramento e Controle Prof. Dr. J.W. Metzger Institut für Siedlungswasserbau, Wassergüte- und Abfallwirtschaft

2 2 Organic trace analysis yesterday and today milli m 10-3 mikro µ 10-6 nano n 10-9 pico p femto f atto a zepto z mg/kg mg/l 1950 DDT (persistent insecticide) pg/kg pg/l 2000 Aflatoxin M1 (mould toxin; carry over from feed to cow milk)

3 3 Drugs on the watchlist of the EU Water Directive 2000/60/EG» The Commission establishes environmental quality standards so as to limit the quantity of certain chemical substances that pose a significant risk to the environment and to health in surface water in the European Union (EU). The planned environmental quality standards are limits to the degree of concentration, i.e. the quantity in water of the substances concerned must not exceed certain thresholds.«- 17α-Ethinylestradiol (contraceptive) 0,4 ng/l - 17β-Estradiol (natural steroide hormone) 0,035 ng/l - Diclofenac (anti-inflammatory) 100 ng/l

4 4 Steps of Analysis Sampling (water, soil, sewage sludge, sediment, biota) Sample Preparation (filtration, ph adjustment...) Extraction/Enrichment (liquid/liquid or SPE) Clean-Up (silicagel column) Separation (chromatography) Determination/Quantification

5 5 Analysis of micropollutants - Challenges very low environmental concentrations - high risk of loss and contamination - blank values can be high (e.g. phthalates) enrichment of highly polar (water soluble) compounds separation of highly polar analytes in complex sample matrix quantification near the limit of determination (LOD) high measurement uncertainties development of multi-analyte methods which are capable of assessing as many analytes as possible with only one single method (e.g. drugs) selection of suitable analytes (metabolites) from which the desired pieces of information can be obtained; random-screening for new compounds differentiation between dissolved and particle bound portion of analyte

6 6 Sampling grab samples due to the high fluctuations in concentration not very informative better: composite samples, 24h etc. useful: concentration profiles (day, week, month), seasonal changes?

7 7 Part I Detection Detecção

8 8 Instrumental Analysis

9 9 Instrumental Analysis of Micropollutants GC-EI-MS-MS or HPLC-ESI-MS-MS In some cases also direct injection of water samples possible (without HPLC and enrichment /clean-up steps)

10 10 1. Separation of analyte mixtures by chromatography 1.1 Gas chromatography (GC) - non-polar, thermostable molecules - more polar molecules after derivatization (e.g. trimethylsilylation) 1.2 High performance liquid chromatography (HPLC) - suitable for both polar and non-polar and also thermolabile compounds 2. Detection and quantification by tandem (MS-MS) mass spectrometry - ionization: electron impact (GC), electrospray (HPLC) - high specificity by selection of molecular ion and fragment ions - high sensitivity and good signal/noise ratio by reaction monitoring (a tandem MS technique)

11 11 Example: The Analysis of Sweeteners

12 12 Sweeteners Used as sugar substitute in diet or light products (supposed to be more healthy than sugar due to the need of only small quantities and zero calories) high sweetening power in effluents of municipal waste water treatment plants and in surface waters are found: acesulfam, cyclamate, saccharin and sucralose - effluent concentrations 10 to 190 µg/l (highest for acesulfam) - SWTP elimination up to 94% for cyclamate, saccharin - only poor removal: acesulfam, sucralose

13 13 Analysis of Sweeteners HPLC-ESI-MS-MS (electrospray tandem mass spectroscopy), negative ion mode (concentration in treated wastewater: several ten µg/l) Solid phase extraction: e.g. Oasis HLB (Waters), Bakerbond STB at low ph (acid-base equilibrium! Neutral species required); sample volume 50 ml Quantification with deuterated internal standards Zorbax Eclipse XDB-C18 1,8 μm; 50x4,6 mm; methanol/water gradient (both containing 20 mm ammonium acetate); for assurance of peak identity in ambigous cases second run on Hypercarb,150 x 2,1 mm; 5 μm; Thermo Fisher Scientific post-column addition of 20 mm TRIS buffer to increase sensititvity (sucralose!) LODs: 1 10 ng/l M. Scheurer, H.-J. Brauch, F.T. Lange: Analysis and occurrence of seven artificial sweetener in German waste water and surface water, Analytical & Bioanalytical Chemistry 394, , 2009 und M. Scheurer, H.-J. Brauch, F.T. Lange: Die süße Seite der Wasseranalytik, GIT Labor-Fachzeitschrift 10, (2009)

14 14 HPLC-ESI-MS-MS negative ion mode Quantification with deuterated internal standards Zorbax Eclipse XDB-C18 1,8 μm; 50x4,6 mm; methanol/water gradient (both containing 20 mm ammonium acetate) post-column addition of 20 mm TRIS buffer to increase sensititvity (sucralose!) LODs: 1 10 ng/l M. Scheurer et al. GIT Labor-Fachzeitschrift 10, (2009)

15 15 Bioassays

16 16 E-Screen- Assay ISWA Uni Stuttgart Multiple determination Incubation 5 days ISWA Uni Stuttgart c 1 c 2 c 3 c 4 K c c c Concentration c 8 c 9 Comparison of the results to a negative control (K) result expressed in EEQ (estradiol equivalent concentrations) ISWA Uni Stuttgart

17 17 Strength of the E-Screen-Assay Determination of the total estrogenic activity as biological summary parameter EEQ suitable for mixtures (extracts of sewage, soil etc.) can be used as pre-screening method high sensitivity (0.5 ng/l estradiol) 17

18 18 Part II Monitoring and Control Monitoramento e Controle

19 19 Aims Determination of water quality Identification of changes in quality over time Control of environmental quality standards and threshold values Determination of water treatment efficiencies in technical plants Identification of new micropollutants

20 20 Tracer Compounds as Valuable Tools for Monitoring and Control of Micropollutants Municipal Wastewater Biological Wastewater Treatment Surface Water Water From Urban Settlements Water from Agriculture - Live stock farming - Plant cultivation Bank filtration, groundwater recharge Ozonation

21 21 Tracers for Studying the Behaviour of Micropollutants During Biological Wastewater Treatment Requirements for good tracers for studying micropollutants in sewage, e.g. for the determination - of flow pathways - the percentage of waste water in stretches of water (deternination of leakages in the sewerage system) - of wastewater impact on surface and ground water are: entry into the environment mainly by municipal wastewater, no diffuse entry by other sources, it should not occur naturally should be persistent during wastewater treatment A good tracer for aerobic treatment is the sweetener acesulfam: concentration in treated wastewater: µg/L, surface water: up to 3 µg/l

22 22 Further Possible Tracers for Municipal Wastewater Boron: constituent of detergents, but: has also natural sources, no clear relation to wastewater EDTA: constituent of detergents, but: analysis is difficult, high LOD carbamazepin, anticonvulsant and mood- stabilizing drug note: metabolization under anaerobic conditions

23 23 Behaviour of Micropollutants in the Aqueous Environment (Surface Water) Original compound primary degradation mineralization Biological degradation Hydrolysis Photolysis Carbamazepin: Diclofenac - poor biological degradability - poor adsorption - resistant to hydrolysis (at natural ph) - moderate photochemical degradation (month-years) - moderate biological degradability - resistant to hydrolysis - relatively good photochemical degradation (h d) Sulfamethoxazol - good biological degradability - resistant to hydrolysis - relatively good photochemical degradation (hours to days)

24 24 Sorption of Micropollutants to Activated Carbon Adsorption Potential Very good good* Moderate poor* None Micropollutant Benzotriazol, Carbamazin, Diclofenac Acesulfam, Sulfamethoxazol, Primidon iodinated contrast media for X-ray EDTA, methyl-tert. butyl ether (MTBE), ETBE * depending on DOC Some correlation to SAC 254 (spectral absorption coefficient) due to the removal of organic background