Photolytic Breakdown of Trace Level Pharmaceuticals in the Environment
S.A. Kindelberger1
, J.M. Conley2
, S.M. Richards2
of 1

National ACS Poster

Published on: Mar 3, 2016

Transcripts - National ACS Poster

  • 1. Photolytic Breakdown of Trace Level Pharmaceuticals in the Environment S.A. Kindelberger1 , J.M. Conley2 , S.M. Richards2 ,S.J. Symes1 University of Tennessee at Chattanooga Chattanooga, TN 37403 1 Department of Chemistry, 2 Department of Environmental Science Experimental Introduction The fate of both prescription and over-the-counter pharmaceuticals in the environment are largely unknown. Previous studies have shown that these compounds may be present in watershed concentrations high enough to have detrimental biological effects. Current waste water treatment methods are not designed to break down these small organic molecules. Since up to 90% of these compounds can be excreted unchanged by humans, the potential exists for a continuing source of environmental replenishment. It may be that photolytic breakdown is an important mechanism of degradation in the environmental fate of these compounds. Although previous studies have investigated breakdown phenomena in single drug systems, more complex degradation interactions may exist in multi- component systems that have not been evaluated. This study was designed to investigate the possibility of photolytic breakdown in a 13 drug mixture. Acknowledgements References Conclusions Three parent solutions(10μg/mL) were made by solvating each target drug(~10mg) in 50% Type I H2O(Millipore)/50% acetonitrile(Fisher Scientific, Optima grade). Solutions were stirred under dark conditions for 12 hours at 22°C and further diluted with same solvent to experimental concentrations(100ng/mL). Working solutions were filtered(0.22 microns) and placed in 125mL clear borosilicate reactor cells(Fisher Scientific) with a transmission range ~700-280nm. Exposed cells received approximately 8 hours/day of direct and 4 hours/day of indirect unfiltered sunlight in early spring 2008 (Southern TN at approx.35.07°N, 85.27°W, elev.659ft) with a mean temperature of 12.8°C (min=-2.8°C,max=24.4°C). Solutions were sampled at 0, +6, +12, +24, +36, +48, +60, +120 hours and normalized to refrigerated (3°C) unexposed solutions originating from the same parent dilution. Chromatographic separation and detection utilized a Waters UPLC coupled with a Quattro micro triple quadrupole mass spectrometer operated in ESI+ mode. Data shown (Fig.1) represent the mean of background corrected triplicate injections of individual reactors at each sampling interval. Although 3 drugs show considerable breakdown, most demonstrate significant persistence after 120 hrs of environmental exposure. Analytes were classified into 3 categories based on their aquatic persistence. Drugs showing >90% of original concentrations were determined to be “persistent”, while those showing 20-90% were classified as “slow degrading”. Analytes demonstrating less than 20% of initial concentrations were designated “fast degrading”. The solvent system chosen for this experiment was chosen, in part, based on solubility issues of less polar analytes such as atorvastatin and lovastatin. Drugs in aqueous environmental matrices may exhibit different photolytic responses due effects not accounted for in this experiment, such as possible photolytic quenching by dissolved organic matter (DOM). Less polar drugs may undergo adsorption processes to sediment due to lack of solubility in aqueous conditions. Future work will include more realistic environmental conditions and the possible effects they may contribute to the fate of pharmaceuticals. Results •UTC Grote Fund •Provost Student Research Award •Dr. Robert Mebane •National Science Foundation 2005 prescription data and rankings from Halling-Sorensen et al. (1998) CHEMOSPHERE, 36, 357-393 Kolpin et al. (2002) Environ. Sci. Technol., 36, 1202-1211 Pomati et al. (2006) Environ. Sci. Technol., 40, 2442-2447 HN O N OH OH OH O F Atorvastatin Trade Name: Lipitor Susceptibility: Fast-Degrading N NH2 O Carbamazepine Trade Name: Tegretol Susceptibility: Persistent N O OH O N F NH Ciprofloxacin Trade Name: Cipro Susceptibility: Fast-Degrading N CH3 H O FF F Fluoxetine Trade Name: Prozac Susceptibility: Persistent OH NH O CH3 Acetaminophen Trade Name: Tylenol Susceptibility: Persistent N N H3C N N O CH3 O CH3 Caffeine Trade Name: n/a Susceptibility: Persistent O N H3C CH3 S H N NH CH3 N+ O- O Ranitidine Trade Name: Zantac Susceptibility: Fast-Degrading N S N CH3 H3C O O CH3 O OCH3 Diltiazem Trade Name: Cardizem Susceptibility: Persistent N F OH OO O CH3 N N CH3 Levofloxacin Trade Name: Levaquin Susceptibility: Slow-Degrading Cl Cl NH CH3 Sertraline Trade Name: Zoloft Susceptibility: Persistent Trimethoprim Trade Name: Triprim Susceptibility: Persistent N N NH2 H2N H3CO OCH3 OCH3 Sulfamethoxazole Trade Name: Gantanol Susceptibility: Slow Degrading S O O H N N O CH3 H2N Lovastatin Trade Name: Mevacor Susceptibility: Persistent CH3 CH3 O CH3 O H O H H CH3 CH3 O 0 6 12 24 36 48 60 120 0 25 50 75 100 Levofloxacin Ranitidine Ciprofloxacin PercentDrugRemaining Carbamazepine Time Elapsed (hours) Fig.1 Analyte breakdown over a 120 hour period. Data selected to illustrate 3 categories of persistence. See Table 2 for complete results. Table 1 Drug Category U.S. Number of Prescriptions (2005) Acetaminophen analgesic Over-the-Counter Caffeine stimulant Over-the-Counter Ranitidine H2 histamine blocker Over-the-Counter Trimethoprim Anti-infective --- Levofloxacin Anti-infective 14,235,000 Ciprofloxacin Anti-infective 13,280,000 Sulfamethoxazole Anti-infective --- Diltiazem Calcium channel blocker 2,045,000 Carbamazepine Anti-convulsant 2,284,000 Sertraline SSRI 26,976,000 Fluoxetine SSRI 21,403,000 Lovastatin Anti hyperlipidemic --- Atorvastatin Anti hyperlipidemic 63,219,000 Photolytic Susceptibility % Analyte remaining at 120hrs Ranitidine fast-degrading 0.2% Atorvastatin fast-degrading 9.9% Ciprofloxacin fast-degrading 3.0% Levofloxacin slow-degrading 43% Sulfamethoxazole slow-degrading 56% Lovastatin slow-degrading 89% Carbamazepine persistent 97% Sertraline persistent 100% Fluoxetine persistent 100% Acetaminophen persistent 100% Caffeine persistent 100% Trimethoprim persistent 100% Diltiazem persistent 100% Table 2

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