OZONATION OF RANITIDINE UNDER VARIOUS PHYSICOCHEMICAL CONDITIONS. DEGRADATION KINETICS AND INTERMEDIATE BY-PRODUCTS

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1 ZATI F RAITIDIE UDER VARIU PYICCEMICAL CDITI. DEGRADATI KIETIC AD ITERMEDIATE BY-PRDUCT Christophoros Christophoridis, ikolaos Thomaidis Laboratory of Analytical Chemistry, Department of Chemistry, ational and KapodistrianUniversity of Athens, Zografou, Athens 15771, Greece, ntho@chem.uoa.gr Presentation overview Pharmaceuticals Ranitidine zonation Experimental part Effect of various parameters on the degradation of Ranitidine By-product determination workflow Main intermediate byproducts Conclusions 1

2 Pharmaceuticals - Ranitidine umerous pharmaceuticals, personal care products and endocrine disrupting compounds have entered the environment. Levels of ng to several μg/l according to water solubility, physicochemical characteristics, local consumption rates and biodegradability Ranitidine (Zantac) common pharmaceutical (treatment of ulcer, gastrointestinal hypersecretoryconditions and gastroesophagealrefluxes) histamine 2-receptor antagonist with a furan ring structure mainly excreted in urine as an untransformed compound and its main metabolites formed in the liver (30-70%) are ranitidine -oxide, -desmethyl ranitidine and ranitidine - oxide The presence of ranitidine in surface waters and wastewaters in the U has been determined and identified in several studies in the past contains multiple reactive sites that may be labile to ozone oxidation (e.g. conjugated diene, sulphide and electron-rich alkene group) 2

3 zonation effective, robust and widely accepted oxidation technique degradation occurs mainly through direct reaction with aqueous ozone and ozone decay products (mainly hydroxyl radicals). total mineralization is not entirely achieved for many pollutants, often leading to the production of more by-products with higher or increased toxicity levels. 3 selectively attacks organic compounds with high electron density functional groups double bonds C=C activated aromatic rings with Electron donating groups like - 2 -R -R deprotonated amines bjectives of this study to assess the effects of various operational parameters (p, ozone concentration, presence of hydroxyl radical scavengers, matrix effects and natural organic matter) on the kinetics of the ozonation process to identify the intermediate oxidation byproducts of ranitidine 3

Experimental zonation experiments saturated ozone solution at 4 0 C using ozone AZCZ apparatus Aqueous solutions of ranitidine under various p adjusted (ammonium acetate buffer) sealed bottles

4 Experimental zonation experiments saturated ozone solution at 4 0 C using ozone AZCZ apparatus Aqueous solutions of ranitidine under various p adjusted (ammonium acetate buffer) sealed bottles aqueous solution of ranitidine in the selected buffer was injected with various amounts of saturated ozone solution amples withdrawn in predefined time frames Effects studied olution p matrix ydroxyl radical scavenger t-bu Analysis Kinetics using PLC UV TPs using Bruker qtfm Effect of ozone concentration 5 mg L -1 is enough to degrade more than 85% of the compound Fast reaction in first minutes Total removal with 3 > 4 mg L -1 Pseudo first order rates vary min -1 ( R 2 >0.956) 4

Effect of p Ranitidine removal is enhanced at higher p Amine ozone reactivity at non-protonated forms p>7 ozone decomposed to hydroxyl radicals - 3 D - + 2 - + 2 + - Pseudo first order reaction rates

5 Effect of p Ranitidine removal is enhanced at higher p Amine ozone reactivity at non-protonated forms p>7 ozone decomposed to hydroxyl radicals - 3 D Pseudo first order reaction rates min -1 C o ranitidine 5 mg L -1, ozone initial concentration 1 mg L -1 Effect of matrix content oft and ard simulated drinking water indicated similar degradation rate Alkalinity and bicarbonates usually tend to stabilize aqueous ozone minimizing radical formation C 3- + C (5) 2 C 3 - C 3 2-5

6 Effect of matrix content DM presence Direct ozone reaction radical creation Consuming ozon faster 3 - D D + - evertheless Increased kinetic rates were determined regardless of DC concentration indicating a role of hydroxyl radicals in the degradation of ranitidine scavenger addition addition Presence of scavenger t- Bureduces the reaction rate and overall removal Apparent role of radicals produced with DM and zone Antagonism of oxidative species between DM and ranitidine Pseudo-first order rate constants are similar to higher p values ozone concentration 1.25 mg L -1, initial ranitidine concentration 1 mg L -1 6

7 Mineralization of Ranitidine Reduced mineralization at low ozone concentrations Although at the same concentration Ran is completely removed Transformed to various refractory ozonation by products igher ozone doses need for complete mineralization Mineralization higher at increased p verall kinetics C 3 (mg.l -1 ) C o Ran (mg L -1 ) p t-bu (mm) matrix k obs (min -1 ) R Ultrapure water Ultrapure water Ultrapure water Ultrapure water Ultrapure water Ultrapure water Acetate buffer Acetate buffer Acetate buffer Acetate buffer Acetate buffer Ultrapure water Ultrapure water Ultrapure water

8 C o Ran p t-bu matrix C 3 (mg.l -1 ) (mg.l -1 ) (mm) Drinking Water (medium hardness) Drinking Water (increased hardness) k obs R 2 (min -1 ) DC 2mg.L DC 5mg.L DC 10 mg.l μΜ DC 2mg.L μΜ DC 5mg.L μΜ DC 10 mg.l By product determination workflow Full M Chromatogram preparation Internal Calibration Background subtract Mass exclusions (known m/z) M peak recognition For each t R, m/z accurate Check presence in blank (plus m/z predicted, bibliographic al references) EIC of possible by products tructure elucidation M/M (M/M) minimum maximum elemental formula, m/z tolerances possible chemical formulas Match with structure (best score based on error and isotope patterns) insert possible by products in table using the theoretical and experimental m/z and the calculated error 8

9 Main intermediate byproduct formation on target screening gave 23 possible TPs Blank subtraction and mass accuracy reduced this number to the following suspected TPs EIC Chromatogram of possible TPs not present in blank Intens. x105 4 TP-300 formation of sulfoxide Intens. product x10 5 +M, min # , Background ubtracted, Background ubtracted bbcid M, 25.0eV, min # , Background ubtracted, Background ubtracted m/z m/z t R Compoun d Precursor and productio n Fragment losses Proposed structure Elemental formula Exp mass [M+] + Theor mass [M+] + ppm mda migm a 6.6 P-330 [M+] + - C [M+- C ] C C [M+- C 8 12] C

10 t R Compound Precursor and production Fragment losses Elemental formula Expmass [M+] + Theormass [M+] + ppm mda P-131 [M+] + C P-299 [M+] + C [M+- C C ] P-381 [M+] + C [M+- 2 3] C [M C C ] P-315 [M+] + C [M+- C C ] + migm a P-330 [M+] + C [M+- C C ] + [M+- C C 8 12] 6.6 P-283 [M+]- C P-365 [M+] + C [M+- C C 2] + [M+- 3 2] C [M C C 2 9 3] + [M+- C ] C t R Compound Precursor and production 7.1 P-394 P P-299 P-255 Fragment losses Elemental formula Expmass [M+] + Theormass [M+] + ppm mda migm a [M+] + C [M+ 3] C [M C C 2 7 3] + [M C C ] + [M C C 6 6 3] + [M C C ] + [M C C ] + [M+] + C [M C C ] + [M C C ] + [M+ C3143] C n.a. 7.9 Ranitidine [M+] + C

11 Profile of TP production Relative abundance >1% - + C Exact Mass: ome products with: C Exact Mass: C Exact Mass: C Exact Mass: C Exact Mass: C Exact Mass: C Exact Mass:

Conclusions Ranitidine readily reacts with ozone producing various intermediate by products Reaction is enhances under increased p and initial ozone concentration Pseudo first order K obs reaches 6.

12 Conclusions Ranitidine readily reacts with ozone producing various intermediate by products Reaction is enhances under increased p and initial ozone concentration Pseudo first order K obs reaches 6.06 min -1 DM role as producer of radicals and ozone depleting agent 4 possible different TPs from the beginning of oxidation reaction Mass balance not closed ther ozone concentrations and differences in p are needed Acknowledgments This research has been co-financed by the European Union and Greek national funds through the perational Program "Education and Lifelong Learning" of the ational trategic Reference Framework (RF) ARITEIA624(TREMEPLproject). Thank you for your attention! 12

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