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Unité de recherche REBX Bordeaux, FRANCE

Unité de recherche REBX Bordeaux, FRANCE. Dissipation of polar xenobiotics from pharmaceutical POCIS and suggestion of a performance reference compound N. Mazzella, T. Debenest, J. Grange, C. Madigou, F. Delmas. Introduction. 2.

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Unité de recherche REBX Bordeaux, FRANCE

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  1. Unité de recherche REBX Bordeaux, FRANCE Dissipation of polar xenobiotics from pharmaceutical POCIS and suggestion of a performance reference compound N. Mazzella, T. Debenest, J. Grange, C. Madigou, F. Delmas

  2. Introduction 2 Evaluation of the water quality and its consequences on river biological organisms (WFD) Effects of pesticides and metabolites on diatom communities • Time-weighted average concentration estimates : • Classical grab sampling  Representative ? • Automated/extensive sampling  Time-consuming and expensive • Passive sampling  Validity of quantitative results ?

  3. CPOCIS (1-e-ket) Cwater Cf (t) = = Equilibrium regime ku ku ke ke Cf = = Ksw Linear uptake regime ku >> ke Cf (t) = ku x t time Introduction 3 Assumption of linear isotherms and isotropic exchanges

  4. Aim and objectives 4 • Methodologies • Analytical techniques and analyte recoveries • Calibration of pharmaceutical POCIS • Determination of ku and Rs • Study of analyte elimination rates • Suggestion of a potential PRC

  5. Compression holder washers Polyethersulfone membranes Sorbent Methodologies 5 Analyte recoveries Columns packed with sorbents Elution with MeOH

  6. Herbicides analyzed Large polarity range: -1.7 (Nicosulfuron) ≤ Log Kow ≤ 5.07 (trifluraline) Different classes :Triazines, Phenylureas, Sulfonylureas, Diphenyl ethers,Chloroacetanilides, Dinitroanilines, Benzonitriles, Triketones Triazines and Phenylureas metabolites Analytical method 2 multiresidue methods : HPLC-DAD technique Reverse phase (ODS 2) and weakly anion-exchanger (polyamine) columns Methodologies 6

  7. Methodologies 7 Analysis with an ODS 2 column Separation of 16 neutral or basic herbicides

  8. Methodologies 8 Analysis with a polyamine column Acidic herbicides Log Kow ≤ 0 for Mesotrione Sulcotrione Nicosulfuron

  9. Methodologies 9 Microcosm experimental design Constant temperature (17±1° C) and obscurity Large volume (80 L) Turbulent conditions: constant flow velocity 2-3 cm.s-1

  10. Microcosm experiment Constant temperature and flow velocity, obscurity Tap water Constant concentrations over 21 days of exposure Duplicate analyses CPOCIS 1. Linearity and kinetic regimes 2. Sampling rates Rs Cwater t Calibration of POCIS 10

  11. Calibration of POCIS 11 Cf (L.g-1) 0.974 r 0.998 Days

  12. log KOW -1.7 3.03 5.18 Pendimethalin Calibration of POCIS 12 Sampling rates over 21 days

  13. Calibration of POCIS 13 Cf (L.g-1) r=0.326 r=0.786 r=0.985 Days Sorbent saturation or isotropic exchanges ?

  14. Calibration of POCIS 14 Partial conclusion Linear uptakes of 16 herbicides for 21 days Curvilinear uptakes of DIA and 3 other polar herbicides : • Assumption of isotropic exchanges for DIA • Estimation of the elimination rate constant • Use of DIA as PRC ?

  15. Performance Reference Compound kePRC=ln(CPRC0/CPRC)/t ku KSW = ke CPRC/CPRC0 Rsin situ= (kein situ/kecal) x Rscal t Suggestion of a PRC 15 Rs depends on : Temperature Turbulence Biofouling CPOCIS x MPOCIS Cw = Rs x t

  16. Suggestion of a PRC 16 Dissipation of DIA and simazine from pharmaceutical POCIS C/C0 Simazine DIA Days Elimination rate constant estimates : ke= 0.047± 0.005 d-1 (dissipation) and ke= 0.08± 0.02 d-1 (uptake) Isotropic exchanges might exist for DIA

  17. Suggestion of a PRC 17 Microcosm experiment Turbulent flow (20-50 cm.s-1) River water (biofouling effects) 9-day exposure Correction of TWA concentrations (PRC)

  18. µg.L-1 µg.L-1 3 6 9 Days POCIS POCIS (PRC) « Peak » concentration 3 6 9 Days Suggestion of a PRC 18 Terbuthylazine + 25 % Average concentration + 30 % The « peak » concentration was integrated during 9 days

  19. µg.L-1 µg.L-1 POCIS 3 6 9 Days POCIS (PRC) « Peak » concentration 3 6 9 Days Suggestion of a PRC 19 Deethylterbuthylazine + 11 % Average concentration + 25 % DET (log Kow=1.98) Terbuthylazine (log Kow=3.21)

  20. Conclusions and further studies 20 Isotropic exchanges for DIA (first-order monophasic kinetic) « Peak » concentrations are integrated for the 2 test chemicals Correction of TWA concentration estimates for 9 days Desorption of DIA and other herbicides for 28 days (biphasic kinetics) Correction of TWA concentrations for 21-28 days In situ validation with one or several PRCs

  21. Unité de recherche REBX Bordeaux, FRANCE Thank you for your attention !

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