Factors hindering the degradation of pharmaceuticals from human urine in an iron-activated persulfate system

This study investigated the degradation of clofibric acid (CFA), bezafibrate (BZF), and sulfamethoxazole (SMX) in synthetic human urine using a novel mesoporous iron powder-activated persulfate system (mFe-PS system), and identified the factors limiting their degradation in synthetic human urine. A kinetic model was established to expose the radical production in various reaction conditions, and experiments were conducted to verify the modeling results. In the phosphate-containing mFe-PS system, the 120 min removal efficiency of CFA decreased from 95.1% to 76.6% as the phosphate concentration increased from 0.32 to 6.45 mmol/L, but recovered to 90.5% when phosphate concentration increased to 16.10 mmol/L. Meanwhile, the increased concentration of phosphate from 0.32 to 16.10 mmol/L reduced the BZF degradation efficacy from 91.5% to 79.0%, whereas SMX removal improved from 37.3% to 62.9%. The mFe-PS system containing (bi)carbonate, from 4.20 to 166.70 mmol/L, reduced CFA and BZF removal efficiencies from 100% to 76.8% and 80.4%, respectively, and SMX from 83.5% to 56.7% within a 120-min reaction time. In addition, alkaline conditions (pH ≥ 8.0) inhibited CFA and BZF degradations, while nonacidic pH (pH ≥ 7.0) remarkably inhibited SMX degradation. Results of the kinetic model indicated the formation of phosphate (H2PO4·/HPO4·-) and/or carbonate radicals (CO3·-) could limit pharmaceutical removal. The transformation products (TPs) of the pharmaceuticals revealed more incompletely oxidized TPs occurred in the phosphate- and (bi)carbonate-containing mFe-PS systems, and indicated that H2PO4·/HPO4·- mainly degraded pharmaceuticals via a benzene ring-opening reaction while CO3·- preferentially oxidized pharmaceuticals via a hydroxylation reaction.

Prevalence of organic micropollutants in the Yamuna River, Delhi, India: seasonal variations and governing factors

This work primarily emphases on evaluating the prevalence of organic micropollutants (OMPs) in the perennial Yamuna River (YR) that flow through the national capital of India, Delhi. Sixteen sampling campaigns (non-monsoon, n = 9; monsoon n = 7) were organized to understand the seasonal variations with special emphasis on monsoon. We have found fifty-five OMPs in the monsoon; while forty-seven were detected in non-monsoon. Fifty-seven screened and quantified OMPs in the most polluted stretch of River Yamuna included the pharmaceutically active compounds, pesticides, endocrine-disrupting chemicals, phthalates, personal care products, fatty acids, food additives, hormones, and trace organics present in hospital wastes. During monsoon months, compounds for which concentrations exceeded 50 μg/L were: adenine (64.6 μg/L), diethyl phthalate (62.9 μg/L), and octamethyltrisiloxane (56.9 μg/L); and the same for non-monsoon months was only for 1-dodecanethiol (52.3 μg/L). The average concentration of OMPs in non-monsoon months indicate PhACs>PCPs>Pesticides>Fatty acids>Hospital waste>Hormones>Pesticides>EDCs. In monsoon months due to surface runoff and high volume of untreated wastewater discharges few more OMPs concentrations were detected which mainly includes PhACs (clofibric acid, diclofenac sodium, gemfibrozil, ketoprofen), pesticides (aldrin, metribuzin, atrazine, simazine). Due to dilution effect in the monsoon months, average concentrations of 3-acetamido-5-bromobenzoic acid (PhACs) was reduced from 45.22 μg/L to 14.07 μg/L, whereas some EDCs such as 2,4- Di-tert-amylphenol, 3,5- di-tert-butyl-4-hydroxybenzyl alcohol, Triphenylphosphine oxide, Benzophenone were found in much higher concentrations in the monsoon months. Octamethyltrisiloxane (PCPs) was detected 50 times higher in concentration in the monsoon months. Interestingly, the concentration of about 50 % of the OMPs was more in the monsoon samples than in non-monsoon samples which is contrary to the general understanding that monsoon-induced dilution lowers the concentrations of OMPs. In RY water higher magnitude of diclofenac sodium, ibuprofen, ketoprofen, and clofibric acid was found than Europe and North America rivers. Hormones such as estriol and estrone in RY water are found 70 to 100 times higher than the maximum reported concentrations in the US streams. Finally, various OMPs responded differently to the monsoon season as evident from multivariate analyses.

Characteristics of removal of waste-water marking pharmaceuticals with typical hydrophytes in the urban rivers

The investigations on their variation and distribution of 13 called waste-water marking pharmaceuticals (WWMPs) were conducted under 4 hydrophyte conditions (without plants, with submerged aquatic plant (Myriophyllum verticillatum L.), emergent aquatic plant cattail (Typha orientalis Presl) and floating aquatic plant (Lemna minor L.)) in a simulated urban river system. By the calculation of mass balance, the quantitative distribution of WWMPs in water phase, sediment and plant tissues was identified, and the overall removal efficiencies of target pharmaceuticals in the whole system could be determined. Without plants, high persistence of atenolol (ATL) (97.7%), carbamazepine (CBM) (102.8%), clofibric acid (CLF) (101.8%) and ibuprofen (IBU) (80.9%) was detected in water phase, while triclosan (TCS) (53.5%) displayed strong adsorption affinity in sediment. The removal under the planted conditions was considerably raised, compared with no plant condition for most WWMPs. However, TCS did not show obvious differences among the hydrophyte conditions due to its strong adsorption affinity and high hydrophobicity. The relatively higher removal was found for the hydrophilic (logK_ow<1) or moderately hydrophobic (1<logK_ow<3) pharmaceuticals with submerged and emergent aquatic plants. The highly hydrophobic pharmaceuticals (logK_ow>4.0) did not show significant differences among the whole tests in sediment. Mass balance calculation displayed the removal of CBM (5.6%-13.6%), CLF (4.0%-17.8%) and caffeine (8.4%-17.2%) through the plant uptake was relatively higher. For the rest WWMPs, only small parts (<6.0%) of the initial concentrations were found in plant tissues. The higher removal efficiencies of most WWMPs under the planted conditions indicated that aquatic plants indeed played an important role in the removal of WWMPs although the direct uptakes might not be a dominant pathway to the overall removal of WWMPs. Besides, the floating aquatic plant removed most WWMPs from the water phase efficiently. In contrast, submerged and emergent aquatic plants could effectively remove them in sediment.

Comparison of pharmaceutical abatement in various water matrices by conventional ozonation, peroxone (O3/H2O2), and an electro-peroxone process

Pharmaceutical abatement in a groundwater (GW), surface water (SW), and secondary effluent (SE) by conventional ozonation, the conventional peroxone (O₃/H₂O₂), and the electro-peroxone (E-peroxone) processes was compared in batch tests. SE had significantly more fast-reacting dissolved organic matter (DOM) moieties than GW and SW. Therefore, O₃ decomposed much faster in SE than in GW and SW. At specific ozone doses of 0.5-1.5 mg O₃/mg dissolved organic carbon (DOC), the application of O₃/H₂O₂ and E-peroxone process (by adding external H₂O₂ stocks or in-situ generating H₂O₂ from cathodic O₂ reduction during ozonation) similarly enhanced the OH yield from O₃ decomposition by ∼5-12% and 5-7% in GW and SW, respectively, compared to conventional ozonation. In contrast, due to the slower reaction kinetics of O₃ with H₂O₂ than O₃ with fast-reacting DOM moieties, the addition or electro-generation of H₂O₂ hardly increased the OH yield (<4% increases) in SE. Corresponding to the changes in the OH yields, the abatement efficiencies of ozone-resistant pharmaceuticals (ibuprofen and clofibric acid) increased evidently in GW (up to ∼14-18% at a specific ozone dose of 1.5 mg O₃/mg DOC), moderately in SW (up to 6-10% at 0.5 mg O₃/mg DOC), and negligibly in SE during the O₃/H₂O₂ and E-peroxone treatment compared to conventional ozonation. These results indicate that similar to the conventional O₃/H₂O₂ process, the E-peroxone process can more pronouncedly enhance O₃ transformation to OH, and thus increase the abatement efficiency of ozone-resistant pharmaceuticals in water matrices exerting relatively high ozone stability (e.g., groundwater and surface water with low DOM contents). Therefore, by installing electrodes in existing ozone reactors, the E-peroxone process may provide a convenient way to enhance pharmaceutical abatement in drinking water applications, where groundwater and surface water with low DOM contents are used as the source waters.

Effect of pore structure on the removal of clofibric acid by magnetic anion exchange resin

The effect of pore structure of resin on clofibric acid (CA) adsorption behavior was investigated by using magnetic anion exchange resins (ND-1, ND-2, ND-3) with increasing pore diameter by 11.68, 15.37, 24.94 nm. Resin with larger pores showed faster adsorption rates and a higher adsorption capacity because the more opened tunnels provided by larger pores benefit the CA diffusion into the resin matrix. The ion exchange by the electrostatic interactions between Cl-type resin and CA resulted in chloride releasing to the solution, and the ratio of released chloride to CA adsorption amount decreased from 0.90 to 0.65 for ND-1, ND-2 and ND-3, indicating that non-electrostatic interactions obtain a larger proportional part of the adsorption into the pores. Co-existing inorganic anions and organic acids reduced the CA adsorption amounts by the competition effect of electrostatic interaction, whereas resins with more opened pore structures weakened the negative influence on CA adsorption because of the existence of non-electrostatic interactions. 85.2% and 65.1% adsorption amounts decrease are calculated for resin ND-1 and ND-3 by the negative influence of 1 mmol L^-1 NaCl. This weaken effect of organic acid is generally depends on its hydrophobicity (Log Kow) for carboxylic acid and its ionization degree (pKb) for sulfonic acid. The resins could be reused with the slightly decreases by 1.9%, 3.2% and 5.4% after 7 cycles of regeneration, respectively for ND-1, ND-2 and ND-3, suggesting the ion exchange resin with larger pores are against its reuse by the brine solution regeneration.

Development of a New Microextraction Fiber Combined to On-Line Sample Stacking Capillary Electrophoresis UV Detection for Acidic Drugs Determination in Real Water Samples

A new analytical method coupling a (off-line) solid-phase microextraction with an on-line capillary electrophoresis (CE) sample enrichment technique was developed for the analysis of ketoprofen, naproxen and clofibric acid from water samples, which are known as contaminants of emerging concern in aquatic environments. New solid-phase microextraction fibers based on physical coupling of chromatographic supports onto epoxy glue coated needle were studied for the off-line preconcentration of these micropollutants. Identification and quantification of such acidic drugs were done by capillary zone electrophoresis (CZE) using ultraviolet diode array detection (DAD). Further enhancement of concentration sensitivity detection was achieved by on-line CE “acetonitrile stacking” preconcentration technique. Among the eight chromatographic supports investigated, Porapak Q sorbent showed higher extraction and preconcentration capacities. The screening of parameters that influence the microextraction process was carried out using a two-level fractional factorial. Optimization of the most relevant parameters was then done through a surface response three-factor Box-Behnken design. The limits of detection and limits of quantification for the three drugs ranged between 0.96 and 1.27 µg∙L⁻¹ and 2.91 and 3.86 µg∙L⁻¹, respectively. Recovery yields of approximately 95 to 104% were measured. The developed method is simple, precise, accurate, and allows quantification of residues of these micropollutants in Genil River water samples using inexpensive fibers.

Method for quantifying NSAIDs and clofibric acid in aqueous samples, lumpfish (Cyclopterus lumpus) roe, and zebrafish (Danio rerio) eleutheroembryos and evaluation of their bioconcentration in zebrafish eleutheroembryos

Pharmaceuticals such as nonsteroidal anti-inflammatory drugs (NSAIDs) and lipid regulators are being repeatedly detected at low concentrations (pg · mL^-1-ng · mL^-1) in the environment. A large fraction of these compounds are ionizable. Ionized compounds show different physico-chemical properties and environmental behavior in comparison to their neutral analogs; as a consequence, the quantification methods currently available, based on the neutral molecules, might not be suitable to detect the corresponding ionized compounds. To overcome this problem, we developed a specific analytical method to quantify NSAIDs and lipid regulators (i.e., ibuprofen, diclofenac, naproxen, and clofibric acid) and their ionized compounds. This method is based on three steps: (1) the extraction of the organic compounds with an organic solvent assisted with an ultrasonic probe, (2) the cleaning of the extracts with a dispersive SPE with C₁₈, and (3) the determination of the chemical compounds by GC-MS (prior derivatization of the analytes). We demonstrated that the proposed method can successfully quantify the pharmaceuticals and their ionized compounds in aqueous samples, lumpfish eggs, and zebrafish eleutheroembryos. Additionally, it allows the extraction and the cleanup of extracts from small samples (0.010 g of wet weight in pools of 20 larvae) and complex matrixes (due to high lipid content) and can be used as a basis for bioaccumulation assays performed with zebrafish eleutheroembryos in alternative to OECD test 305.

Photocatalytic degradation of an emerging pollutant by TiO2-coated glass rings: a kinetic study

This work presents the photocatalytic degradation of the pharmaceutical drug clofibric acid in a fixed-bed reactor filled with TiO₂-coated glass rings. Experiments were carried out under UV radiation. A kinetic model that takes into account radiation absorption by means of the local surface rate of photon absorption (LSRPA) has been developed. The LSRPA was obtained from the results of a radiation model. The Monte Carlo method was employed to solve the radiation model, where the interaction between photons and TiO₂-coated rings was considered. Data from experiments carried out with rings with different numbers of catalyst coatings and different irradiation levels were used to estimate the parameters of the kinetic model. A satisfactory agreement was obtained between model simulations and experimental results.

Mechanism for enhanced degradation of clofibric acid in aqueous by catalytic ozonation over MnOx/SBA-15

Comparative experiments were conducted to investigate the catalytic ability of MnO(x)/SBA-15 for the ozonation of clofibric acid (CA) and its reaction mechanism. Compared with ozonation alone, the degradation of CA was barely enhanced, while the removal of TOC was significantly improved by catalytic ozonation (O3/MnO(x)/SBA-15). Adsorption of CA and its intermediates by MnO(x)/SBA-15 was proved unimportant in O3/MnO(x)/SBA-15 due to the insignificant adsorption of CA and little TOC variation after ceasing ozone in stopped-flow experiment. The more remarkably inhibition effect of sodium bisulfite (NaHSO3) on the removal of TOC in catalytic ozonation than in ozonation alone elucidated that MnO(x)/SBA-15 facilitated the generation of hydroxyl radicals (OH), which was further verified by electron spin-resonance spectroscopy (ESR). Highly dispersed MnO(x) on SBA-15 were believed to be the main active component in MnO(x)/SBA-15. Some intermediates were indentified and different degradation routes of CA were proposed in both ozonation alone and catalytic ozonation. The amounts of small molecular carboxylic acids (i.e., formic acid (FA), acetic acid (AA) and oxalic acid (OA)) generated in catalytic ozonation were lower than in ozonation alone, resulting from the generation of more OH.

Macrophytes may not contribute significantly to removal of nutrients, pharmaceuticals, and antibiotic resistance in model surface constructed wetlands

Outdoor shallow wetland mesocosms, designed to simulate surface constructed wetlands to improve lagoon wastewater treatment, were used to assess the role of macrophytes in the dissipation of wastewater nutrients, selected pharmaceuticals, and antibiotic resistance genes (ARGs). Specifically, mesocosms were established with or without populations of Typha spp. (cattails), Myriophyllum sibiricum (northern water milfoil), and Utricularia vulgaris (bladderwort). Following macrophyte establishment, mesocosms were seeded with ARG-bearing organisms from a local wastewater lagoon, and treated with a single pulse of artificial municipal wastewater with or without carbamazepine, clofibric acid, fluoxetine, and naproxen (each at 7.6μg/L), as well as sulfamethoxazole and sulfapyridine (each at 150μg/L). Rates of pharmaceutical dissipation over 28d ranged from 0.073 to 3.0d(-1), corresponding to half-lives of 0.23 to 9.4d. Based on calculated rate constants, observed dissipation rates were consistent with photodegradation driving clofibric acid, naproxen, sulfamethoxazole, and sulfapyridine removal, and with sorption also contributing to carbamazepine and fluoxetine loss. Of the seven gene determinants assayed, only two genes for both beta-lactam resistance (blaCTX and blaTEM) and sulfonamide resistance (sulI and sulII) were found in sufficient quantity for monitoring. Genes disappeared relatively rapidly from the water column, with half-lives ranging from 2.1 to 99d. In contrast, detected gene levels did not change in the sediment, with the exception of sulI, which increased after 28d in pharmaceutical-treated systems. These shallow wetland mesocosms were able to dissipate wastewater contaminants rapidly. However, no significant enhancement in removal of nutrients or pharmaceuticals was observed in mesocosms with extensive aquatic plant communities. This was likely due to three factors: first, use of naïve systems with an unchallenged capacity for nutrient assimilation and contaminant removal; second, nutrient sequestration by ubiquitous filamentous algae; and third, dominance of photolytic processes in the removal of pharmaceuticals, which overshadowed putative plant-related processes.

Fates and transport of PPCPs in soil receiving reclaimed water irrigation

Fates and transport of 9 commonly found PPCPs of the reclaimed water were simulated based on the HYDRUS-1D software that was validated with data generated from field experiments. Under the default scenario in which the model parameters and input data represented the typical conditions of turf grass irrigation in southern California, the adsorption, degradation, and volatilization of clofibric acid, ibuprofen, 4-tert-octylphenol, 4-n-nonylphenol, naproxen, triclosan, diclofenac sodium, bisphenol A and estrone in the receiving soils were tracked for 10 years. At the end, their accumulations in the 90 cm soil profile varied from less than 1 ng g(-1) to about 140 ng g(-1) and their concentrations in the drainage water in the 90 cm soil depth varied from nil to μg L(-1) levels. The adsorption and microbial degradation processes interacted to contain the PPCPs entirely within surface 40 cm of the soil profiles. Leaching and volatilization were not significant processes governing the PPCPs in the soils. The extent of accumulations in the soils did not appear to produce undue ecological risks to the soil biota. PPCPs did not represent any potential environmental harm in reclaimed water irrigation.

Fate of pharmaceutical compounds in hydroponic mesocosms planted with Scirpus validus

A systematic approach to assess the fate of selected pharmaceuticals (carbamazepine, naproxen, diclofenac, clofibric acid and caffeine) in hydroponic mesocosms is described. The overall objective was to determine the kinetics of depletion (from solution) and plant uptake for these compounds in mesocosms planted with S. validus growing hydroponically. The potential for translocation of these pharmaceuticals from the roots to the shoots was also assessed. After 21 days of incubation, nearly all of the caffeine, naproxen and diclofenac were eliminated from solution, whereas carbamazepine and clofibric acid were recalcitrant to both photodegradation and biodegradation. The fact that the BAFs for roots for carbamazepine and clofibric acid were greater than 5, while the BAFs for naproxen, diclofenac and caffeine were less than 5, implied that the latter two compounds although recalcitrant to biodegradation, still had relatively high potential for plant uptake. Naproxen was sensitive to both photodegradation (30-42%) and biodegradation (>50%), while diclofenac was particularly sensitive (>70%) to photodegradation alone. No significant correlations (p > 0.05) were found between the rate constants of depletion or plant tissue levels of the pharmaceuticals and either log Kow or log Dow.

Assessment of plant-driven uptake and translocation of clofibric acid by Scirpus validus

Pharmaceutical compounds are now considered as emerging contaminants of environmental concern. The overall objective of this study was to evaluate the uptake and translocation of clofibric acid (CA) by the macrophyte Scirpus validus growing hydroponically. A set of the three replicates was established for each exposure time and for each CA concentration. Plants were grown in 4 L vessels (four plants per vessel corresponding to the three exposure period studies, i.e., 7, 14, 18, and 21 days) which contained an aerated modified Hoagland nutrient solution that was spiked with CA at concentrations of 0.5, 1.0, and 2.0 mg L(-1). At each exposure period, CA concentration was measured in the nutrient solutions. A sea sand disruption method was employed for the extraction of CA from plant tissues. The determination of the pharmaceutical concentration was carried out using solid phase extraction (SPE) followed by chromatographic analysis. The quantification of CA concentrations in both nutrient solutions (after SPE) and plant tissues (after extraction) was conducted by chromatographic analysis. CA concentrations of 5.4-26.8 μg g(-1) (fresh weight) were detected in the roots and 7.2-34.6 μg g(-1) (fresh weight) in the shoots after 21 days. Mass balance calculations showed that S. validus uptake alone accounted for a significant contribution (6-13% for the roots and 22-49% for the shoots) of the total loss of CA. The bioaccumulation factors (BAFs) based on fresh weight for the roots ranged from 6.6 to 23.2, while values for the shoots ranged from 9.5 to 32.1. All the BAFs for the shoots were greater than those in the roots, implying that CA has greater tendency to be translocated to the shoots, rather than the roots of S. validus. All the shoot-to-root concentration ratios were more than 1, denoting that the shoots of S. validus do preferentially accumulate CA. We demonstrated that CA can be actively taken up, subsequently translocated and accumulated by aboveground tissues of S. validus. Since S. validus could account for the removal of 28-62% of the total mass loss of CA from the system, such phytoremediation technology has great potential for the removal of pharmaceuticals such as CA from inflowing waters.

[Occurrence and risk assessment of five selected PPCPs in municipal wastewater treatment plant and the receiving water]

Five PPCPs, including clofibric acid (CA), diclofenac (DFC), ibuprofen (IBP), ketoprofen (KEP), and naproxen (NPX) were selected as target compounds to investigate their occurrence and removal efficiency in a wastewater treatment plant (WWTP) of Shanghai. Furthermore, their distribution and potential toxicological risk in the WWTP receiving river water were investigated. The results showed that all targets were detected in WWTP influent, suggesting that domestic sewage discharge is an important source of PPCPs to the WWTP. Lower removal efficiency of these PPCPs was found in the WWTP and the main mechanism of elimination was biodegradation. The pattern of five selected PPCPs in the river was similar to that in WWTP effluent, indicating that WWTP effluent was a main source of PPCPs to the receiving water. Risk assessment showed that diclofenac posed a high risk, while ketoprofen, naproxen, clofibric acid and ibuprofen showed low risks to biota in the receiving river.

Multi-phase partitioning, ecological risk and fate of acidic pharmaceuticals in a wastewater receiving river: the role of colloids

The occurrence and multi-phase distribution of five pharmaceutical compounds were investigated in an urban wastewater treatment plant (WWTP) receiving river by analysis of pharmaceuticals in sediment, particulate matter, conventional dissolved phase (>0.7 μm), colloidal phase (5 kDa to 0.7 μm), and truly dissolved phase (<5 kDa) water. Diclofenac was found in all samples, followed by clofibric acid, ibuprofen, ketoprofen, and naproxen with the decreasing detection frequency. All targets in WWTP outfall site were higher than those in the upstream and downstream, indicating that the WWTP is an important input source of pharmaceuticals in the river. The colloidal phase contributed 10-14% of ketoprofen, 8-26% of naproxen, 17-36% of clofibric acid, 22-33% of diclofenac, and 9-28% of ibuprofen in the aquatic system, suggesting the colloids will play an important role as carrier to contaminants in the aquatic environment. Based on truly dissolved concentrations of pharmaceuticals in water, only the risk quotient (RQ) value for diclofenac towards fish was higher than 1, indicating it poses a potential risk to aquatic organisms. Finally, a Level III fugacity model was used to further assess the environmental fate of the selected pharmaceuticals (exemplified for clofibric acid and diclofenac). Both clofibric acid and diclofenac tend to accumulate in water compartment with the percentage of 99.7% and 60.6%, respectively. Advection in river is a significant loss process for clofibric acid (56.4%) and diclofenac (54.4%).

Batch versus continuous feeding strategies for pharmaceutical removal by subsurface flow constructed wetland

This study evaluated the effect of continuous and batch feeding on the removal of 8 pharmaceuticals (carbamazepine, naproxen, diclofenac, ibuprofen, caffeine, salicylic acid, ketoprofen and clofibric acid) from synthetic wastewater in mesocosm-scale constructed wetlands (CWs). Both loading modes were operated at hydraulic application rates of 5.6 cm day(-1) and 2.8 cm day(-1). Except for carbamazepine, clofibric acid and naproxen, removal in CWs was significantly (p < 0.05) enhanced under the batch versus continuous mode. For all compounds tested except naproxen, values for first-order decay constants (k) for drain and fill operation were higher than that for the continuous mode of operation. Correlation between the distribution coefficient (log D(ow)) and removal efficiencies of pharmaceutical compounds in the CWs, showed that pharmaceutical removal efficiency was significantly (p < 0.1) and inversely correlated with log D(ow) value, but not with log K(ow) value.

Distribution and temporal evolution of pharmaceutically active compounds alongside sewage sludge treatment. Risk assessment of sludge application onto soils

In this work, the distribution and the ecotoxicological risk of sixteen pharmaceutically active compounds belonging to seven different therapeutic groups (five anti-inflammatory drugs, two antibiotics, an anti-epileptic drug, a β-blocker, a nervous stimulant, four estrogens and two lipid regulators) have been studied in sewage sludge from wastewater treatment plants. Only three of the sixteen pharmaceutical compounds were never detected in sludge while eleven of the studied pharmaceuticals were still detected in compost. Mean concentration levels of the pharmaceutically active compounds ranged between 24.9 and 4105 μg/kg dm, 14.5-944 μg/kg dm, 3.29-636 μg/kg dm and 9.19-974 μg/kg dm in primary, secondary, digested sludge and compost, respectively. An increase in the concentration levels of most of the pharmaceuticals was observed from summer to winter (mean values in primary and secondary sludge were 304 and 85.1 μg/kg dm in summer and 435 and 175 μg/kg dm in winter, respectively) probably due to an increase of their consumption during the coldest season and a reduction of the microbial activity under colder temperatures. The highest ecotoxicological risk, in digested sludge and compost, was due to the estrogenic compound 17β-estradiol. The ecotoxicological risk significantly decreased after the application of digested sludge or compost to the soils (risk quotient values ranged between 0.04 and 252 in digested sludge and 0.002-37.8 in compost and decreased to 8·10(-4)-1.92 in digested sludge-amended soil and 1·10(-4)-0.23 in compost-amended soil).

Pharmaceutical removal in tropical subsurface flow constructed wetlands at varying hydraulic loading rates

Determining the fate of emerging organic contaminants in an aquatic ecosystem is important for developing constructed wetlands (CWs) treatment technology. Experiments were carried out in subsurface flow CWs in Singapore to evaluate the fate and transport of eight pharmaceutical compounds. The CW system included three parallel horizontal subsurface flow CWs and three parallel unplanted beds fed continuously with synthetic wastewater at different hydraulic retention times (HRTs). The findings of the tests at 2-6 d HRTs showed that the pharmaceuticals could be categorized as (i) efficiently removed compounds with removal higher than 85% (ketoprofen and salicylic acid); (ii) moderately removed compounds with removal efficiencies between 50% and 85% (naproxen, ibuprofen and caffeine); and (iii) poorly removed compounds with efficiency rate lower than 50% (carbamazepine, diclofenac, and clofibric acid). Except for carbamazepine and salicylic acid, removal efficiencies of the selected pharmaceuticals showed significant (p<0.05) enhancement in planted beds as compared to the unplanted beds. Removal of caffeine, ketoprofen and clofibric acid were found to follow first order decay kinetics with decay constants higher in the planted beds than the unplanted beds. Correlations between pharmaceutical removal efficiencies and log K(ow) were not significant (p>0.05), implying that their removal is not well related to the compound's hydrophobicity.

Reactive tracer test to evaluate the fate of pharmaceuticals in rivers

The fate of pharmaceutically active substances in rivers is still only incompletely understood, especially as the knowledge transfer from laboratory experiments to the real world is complicated by factors like turbidity, hydrodynamics, or heterogeneity. Therefore, we performed a tracer test with pharmaceutically active substances to study their fate and the importance of individual attenuation mechanisms in situ. The experiment was carried out at a small stream in central Sweden. Two dye tracers and six pharmaceuticals were injected as Dirac pulse and water was sampled at five downstream sites along a 16-km-long river reach. Ibuprofen and clofibric acid were the only compounds which were eliminated along the study reach at half-life times of 10 h and 2.5 d, respectively. Based on the shape of the breakthrough curves and the low hydraulic conductivity of the river bed, we can assume that exchange of river water with the hyporheic zone was minor. Thus, the contribution of processes in the hyporheic zone to the attenuation of pharmaceuticals was low. We hypothesize that ibuprofen and clofibric acid were transformed by in-stream biofilms growing on submerged macrophytes and at the water-sediment interface. Phototransformation and sorption were ruled out as major attenuation processes. No attenuation of bezafibrate, diclofenac, metoprolol, and naproxen was observed.

Methods of chromatographic determination of medicines decreasing the level of cholesterol

With reference to common application of HPLC to routine analytical tests on medicinal products decreasing the level of cholesterol, including three compounds from this group--fenofibrate, bezafibrate and etofibrate, we developed a new method for determining two other compounds--ciprofibrate and gemfibrozil. The developed HPLC method may be used for identification and qualitative determination of selected compounds--derivatives of aryloxyalkylcarboxylic acids as well as it may be used for simultaneous separation and determination of all compounds from the group of fibrates using one column and the same methodology. The results and statistical data indicate good sensitivity and precision. The RSD value presented is equivalent to the newly developed method of determinination of ciprofibrate and gemfibrozil in the substances and medicinal products--capsules and coated tablets.

Degradation and adsorption of selected pharmaceuticals and personal care products (PPCPs) in agricultural soils

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in the environment, which have drawn popular concerns recently. Most studies on the environmental fate of PPCPs have focused on their behaviors during wastewater treatment processes, in aquatic environments, and in the sludge, however, little is known about their behavior in agricultural soils. In this study, adsorption and degradation of six selected PPCPs, including clofibric acid, ibuprofen, naproxen, triclosan, diclofenac and bisphenol A have been investigated in the laboratory using four US agricultural soils associated with reclaimed wastewater reuse. Adsorption test using a batch equilibrium method demonstrated that adsorption of all tested chemicals in soils could be well described with Freundlich equation, and their adsorption affinity on soil followed the order of triclosan>bisphenol A>clofibric acid>naproxen>diclofenac>ibuprofen. Retardation factor (R(F)) suggested that ibuprofen had potential to move downward with percolating water, while triclosan and bisphenol A were readily retarded in soils. Degradation of selected PPCPs in soils generally followed first-order exponential decay kinetics, with half-lives ranging from 0.81 to 20.44 d. Degradation of PPCPs in soils appeared to be influenced by the soil organic matter and clay contents. Sterilization generally decreased the degradation rates, indicating microbial activity played a significant role in the degradation in soils. The degradation rate constant decreased with increasing initial chemical concentrations in soil, implying that the microbial activity was inhibited with high chemical loading levels.

Determination of etofibrate, fenofibrate, and atorvastatin in pharmaceutical preparations and plasma using differential pulse polarographic and square wave voltammetric techniques

Etofibrate, fenofibrate, and atorvastatin were determined in their pharmaceutical preparations and human plasma using differential pulse polarographic and square wave voltammetric techniques by reduction at a dropping-mercury working electrode versus Ag/AgCl reference electrode. The reversibility of the electrode reactions was tested using cyclic voltammetry, and they were found to be irreversible reduction reactions. Optimum conditions such as pH, scan rate, and pulse amplitude were studied, and validation of the proposed methods was performed. The proposed methods proved to be accurate, precise, robust, and specific for determination of the 3 drugs. The relative standard deviation values were <2%, indicating that these methods are precise. Limits of detection and quantitation were in the ranges of 0.037-0.21 and 0.12-0.71 microg/mL, respectively, indicating high sensitivity.

Selection of a support matrix for the removal of some phenoxyacetic compounds in constructed wetlands systems

The efficiency of constructed wetlands systems in the removal of pollutants can be significantly enhanced by using a support matrix with a greater capacity to retain contaminants by sorption phenomena, ionic exchange or other physico-chemical processes. The aim of this work was to evaluate the efficiencies of 3 different materials, Light Expanded Clay Aggregates [LECA] (in two different particle sizes), Expanded Perlite and Sand, for the removal from water of one pharmaceutical compound (clofibric acid) and one pesticide (MCPA). Both belong to the class of phenoxyacetic compounds. In addition, relationships were established between the compounds' removal efficiencies and the physico-chemical properties of each material. LECA exhibited a high sorption capacity for MCPA, while the capacity for clofibric acid was more modest, but still significant. In contrast, perlite had a very limited sorption capacity while sand did not exhibit any sorption capacity for any of the compounds. LECA with smaller particle sizes showed higher efficiencies than larger grade LECA and can achieve efficiencies near 100% for the lower concentrations in the order of 1 mg l(-1). However, the use of these smaller particle media at larger scales may present problems with hydraulic conductivities. The results show that expanded clay presents important advantages in laboratory studies and could be used as a filter medium or a support matrix in constructed wetlands systems.

High performance liquid chromatographic determination of etofibrate and its hydrolysis products

High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile-10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min(-1). The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton-Robinson buffer solutions within the pH range 2-10 were studied.

Separation of fibrate-type antihyperlipidemic drugs by capillary electrophoresis and their quantitation in pharmaceuticals

Six antihyperlipidemic agents-bezafibrate, ciprofibrate, clofibrate, clofibric acid, fenofibrate and gemfibrozil were separated by means of capillary electrophoresis, using unmodified fused silica tubing of 75 microm internal diameter and 87 cm length (65 cm to the UV detector at 227 nm). Migration time and selectivity were examined in differing pH of separation buffer, varying separation voltage and differing temperature. Optimal separation was achieved using 1/15 M phosphate buffer pH 10, 240 V/cm at 25 degrees C. The optimal separation conditions were then used to elaborate the method of quantitation of bezafibrate, ciprofibrate and gemfibrozil in Bezamidin, Lipanor and Gemfibral pharmaceuticals. The clofibric acid was used as internal standard. The calibration curve was constructed from 0.2 to 0.8 mg/ml of each compound and 0.5 mg/ml of internal standard. The calibration data were proved to be linear by Mandel and Lack-of-fit tests. Statistical evaluation of results proved proper recovery of elaborated method (102.42, 97.32 and 101.51%, respectively) and good repeatability (9.51, 5.52 and 11.15%, respectively). The linearity of recovery was also tested by analyzing increasing amount of the samples. Three fortified samples of each drug were also analyzed to perform additional accuracy validation.

Behavior of selected pharmaceuticals in subsurface flow constructed wetlands: a pilot-scale study

Subsurface flow constructed wetlands (SSFs) constitute a wastewater treatment alternative to small communities due to the low operational cost, reduced energy consumption, and no sewage sludge production. Although much information is available about conventional water quality parameters in SSF constructed wetlands, few data are available regarding specific contaminants. In this paper, we focus on the behavior of three widely used pharmaceuticals (clofibric acid, ibuprofen, and carbamazepine) in two pilot SSF constructed wetlands planted with Phragmites australis and characterized by different water depths (i.e., 0.3 and 0.5 m). These SSFs partially treat the urban wastewater from a housing development (ca. 200 inhabitants). The three pharmaceuticals and bromide were continuously injected into the two SSFs during a period of 150-200 h, and the effluent concentration was simultaneously measured as 6 h composite samples. Their removal efficiency was calculated from the injected concentration, and the hydraulic parameters were evaluated and compared to bromide as tracer. In this regard, the behavior of clofibric acid was similar to that of bromide, and no sorption into the gravel bed occurred. On the other hand, carbamazepine showed a higher sorption than bromide and clofibric acid, which is attributable to its interaction on the gravel bed. Accordingly, the use of clofibric acid as a hydraulic tracer is proposed, taking into account its low residence time. Ibuprofen removal was 81% in the shallow SSF and 48% in the deep one. Differences in removal efficiency could be explained by the less anaerobic environment of the shallow wetland.

Occurrence of several acidic drugs in sewage treatment plants in Switzerland and risk assessment

The occurrence and fate of five acidic drugs (Mefenamic acid, Ibuprofen, Ketoprofen, Diclofenac and Clofibric acid) were analysed in three sewage treatment plants (STP) over 4-7 consecutive days. The results point out that the five substances were persistent in wastewater effluents after municipal wastewater treatment. At the most, half of Mefenamic acid was eliminated. Ibuprofen was well removed (80%) by one sewage treatment plant. The removal of Ibuprofen is dependent on the residence time of wastewater in the STPs. A long raining period induce an important decrease of removal of Ibuprofen and Ketoprofen. Removal rates showed a great variability according to sewage treatment plants and types of treatments (e.g. biological, physico-chemical). The concentrations of Ibuprofen, Mefenamic acid and Diclofenac were relatively high in the effluents (150-2000 ng/l), showing a potential contamination of surface water. An environmental risk assessment is presented. Mefenamic acid seems to present a risk for the aquatic environment, with a ratio PEC/PNEC higher than one.

Determination of some acidic drugs in surface and sewage treatment plant waters by capillary electrophoresis-electrospray ionization-mass spectrometry

We describe an analytical method involving solid-phase extraction (SPE) and capillary zone electrophoresis-electrospray ionization-mass spectrometry (CZE-ESI-MS) for determining some pharmaceutical compounds - naproxen, clofibric acid and bezafibrate - in real water samples. The electrospray parameters were optimized to maximize sensitivity. When a mixed aqueous-organic solvent and CZE-ESI-MS were used to analyze these drugs in water samples, the capillary was coated with hexadimethrin bromide (HDB) to permanently reverse the EOF. The method was developed from off-line SPE-CZE-MS and was validated with surface water. The detection limits were 100 ng.L(-1) for all analytes. The method was applied to analyze water samples from the influent and effluent of a sewage treatment plant. A liquid-liquid extraction step was required before SPE, and the compounds studied were found, some of them between detection and quantification limits.

Application of UV-derivative spectra for determination of four antihyperlipidaemic drugs in pharmaceutical formulations

A method for the determination of bezafibrate, ciprofibrate, fenofibrate and gemfibrozil in pharmaceutical formulations by first-, second- and third- derivative spectrophotometry is described, using "peak-peak" and "peak-zero" measurements. The calibration graphs were linear in the range 2-20 microg x mL(-1) for all the compounds investigated. No interference was found from tablet excipients at the selected wavelengths and assay conditions. The developed methods were found to be validated and showed good precision and reproducibility (RSD = 1.57%, 0.78%, 1.45%, and 1.36%, respectively).

Ozonation and H2O2/UV treatment of clofibric acid in water: a kinetic investigation

The presence of pharmaceuticals or their active metabolites in surface and ground waters has been recently reported as mainly due to an incomplete removal of these pollutants in sewage treatment plants (STP). Advanced oxidation processes may represent a suitable tool to reduce environmental release of these species by enhancing the global efficiency of reduction of pharmaceuticals in the municipal sewage plant effluents. The present work aims at assessing the kinetics of abatement from aqueous solutions of clofibric acid (a metabolite of the blood lipid regulator clofibrate) which has been found in surface, ground and drinking waters. Ozonation and hydrogen peroxide photolysis are capable of fast removal of this species in aqueous solution, with an almost complete conversion of the organic chlorine content into chloride ions for the investigated reaction conditions. A validation of assessed kinetics at clofibric acid concentrations as low as those found in STP effluents is presented for both systems.

Short-term tests with a pilot sewage plant and biofilm reactors for the biological degradation of the pharmaceutical compounds clofibric acid, ibuprofen, and diclofenac

The biodegradation of three active compounds of pharmaceuticals clofibric acid, ibuprofen, and diclofenac was investigated in short-term tests with a pilot sewage plant (PSP) and biofilm reactors (BFR, oxic and anoxic) as model systems for municipal sewage treatment. The PSP was characterized with respect to mixing behavior, the BFR with respect to biofilm content and sorption of the pharmaceutical compounds. The short-term experiments were carried out for 55 h in the PSP and for 48 h in the BFR. The concentration of the pharmaceuticals was in the microgram per liter range in presence of readily biodegradable substances in the milligram per liter range. Therefore, a too short time period and too low concentration to promote adaption of the microorganisms were applied. Under the operating conditions applied the biodegradation of the lipid lowering agent clofibric acid and the analgesic agents ibuprofen and diclofenac in the oxic BFR resembled that in the PSP. Clofibric acid and diclofenac were not eliminated and reached a level of approximately 95% of their initial concentration, whereas the concentration of ibuprofen was decreased to approximately 40% in the PSP and to approximately 35% in the oxic BFR. Both systems showed, therefore, an inherent ability for ibuprofen biodegradation. Elimination in the anoxic BFR resulted in a decrease of the concentration of all three substances to values between 60 and 80% of their initial concentration. In contrast to the PSP acetone revealed as inhibitor in the BFR. In both systems acetone was not degraded in the short-term tests.

UDP-glucuronosyltransferase-dependent bioactivation of clofibric acid to a DNA-damaging intermediate in mouse hepatocytes

Glucuronidation of a number of carboxyl-containing drugs generates reactive acyl glucuronide metabolites. These electrophilic species alkylate cell proteins and may be implicated in the pathogenesis of a number of toxic syndromes seen in patients receiving the parent aglycones. Whether acyl glucuronides also attack nuclear DNA is unknown, although the acyl glucuronide formed from clofibric acid was recently found to decrease the transfection efficiency of phage DNA and generate strand breaks in plasmid DNA in vitro. To determine if such a DNA damage occurs within a cellular environment, the comet assay (i.e. single-cell gel electrophoresis) was used to detect DNA lesions in the nuclear genome of isolated mouse hepatocytes cultured with clofibric acid. Overnight exposure to 50 microM and higher concentrations of clofibric acid produced concentration-dependent increases in the comet areas of hepatocyte nuclei, with 1 mM clofibrate producing a 3.6-fold elevation over controls. These effects closely coincided with culture medium concentrations of the glucuronide metabolite formed from clofibric acid, 1-O-beta-clofibryl glucuronide. Consistent with a role for glucuronidation in the DNA damage observed, the glucuronidation inhibitor borneol diminished glucuronide formation from 100 microM clofibrate by 98% and returned comet areas to baseline levels. Collectively, these results suggest that the acyl glucuronide formed from clofibric acid is capable of migrating from its site of formation within the endoplasmic reticulum to generate strand nicks in nuclear DNA.

Drugs and personal care products as ubiquitous pollutants: occurrence and distribution of clofibric acid, caffeine and DEET in the North Sea

An analytical method is presented, which allows the simultaneous extraction of neutral and acidic compounds from 20-L seawater samples at ambient pH (approximately 8.3). It is based on a solid-phase extraction by means of a polystyrene-divinylbenzene sorbent and gas chromatographic-mass spectrometric detection, and provides detection limits in the lower pg/L range. The method was applied to the screening of samples from different North Sea areas for clofibric acid, diclofenac, ibuprofen, ketoprofen, propyphenazone, caffeine and N,N-diethyl-3-toluamide (DEET). Whereas clofibric acid, caffeine and DEET showed to be present throughout the North Sea in concentrations of up to 1.3, 16 and 1.1 ng/L, respectively, propyphenazone could only be detected after further clean-up. Diclofenac and ibuprofen were found in the estuary of the river Elbe (6.2 and 0.6 ng/L, respectively) but in none of the marine samples. Ketoprofen was below the detection limit in all samples.

Detection of pharmaceutical contaminations of river, pond, and tap water from Cologne (Germany) and surroundings

A method for the simultaneous determination of polar pharmaceutical compounds in water is presented. Samples from 27 rivers and ponds were investigated for contents of Gemfibrocil, a lipid blood regulating compound, Clofibric acid, a metabolite of lipid regulating compounds (Clofibrat, Etofibrat, Etofyllinclofibrat), antirheumatics (Diclofenac, Ibuprofen, Ketoprofen, Indomethacin, Fenoprofen) and Sarkosin-N-(phenylsulfonyl) (SPS), a metabolite of a corrosion inhibiting agent. In addition water samples were investigated for some main metabolites of Ibuprofen, 2-[4-(2-hydroxy-2-methylpropyl)phenyl]propionic acid (hydroxy-ibuprofen) and 2-[4-(2-carboxypropyl)phenyl]propionic acid (carboxy-ibuprofen), which are excreted after oral intake. For gas chromatographic analysis the drugs were converted into their methyl-derivatives by "on column" reaction with TMSH, TMAH and "pre column" with diazomethane. The detection limits with TMSH were in the same range or lower than those with diazomethane or TMAH. The compound most frequently found was SPS which was only absent in waters with natural surroundings. Diclofenac could be detected in 10 out of 27 water samples in concentrations of up to 15 micrograms/l. In contrast, none of the pharmaceuticals investigated were present in 8 drinking water samples from Cologne and surroundings. Though concentrations measured were far below pharmacological doses, the data suggest a steady flux of these drugs into the environment.

Occurrence of pharmaceutical contaminants and screening of treatment alternatives for southeastern Louisiana

Recent studies conducted in Germany, Switzerland, Denmark, Brazil, Canada, the United States, and elsewhere indicate that low-level concentrations of pharmaceuticals and personal-care products (PPCPs) and their metabolites may be widespread contaminants in our aquatic environment. The persistence of pharmaceutical contaminants has been attributed to (1) human consumption of drugs and subsequent discharges from sewage treatment plants, and (2) veterinary use of drugs and nonpoint discharges from agricultural runoff. Contamination of water resources by these compounds, particularly endocrine disrupting chemicals (EDCs), is emerging as an international environmental concern. The long-term effects of continuous, low-level exposure to PPCPs is not well understood. Preliminary data for raw water samples collected from the Mississippi River and Lake Pontchartrain, Louisiana, are summarized. Three PPCP compounds (clofibric acid, naproxen, and estrone) were analyzed using solid-phase extraction, derivatization, and GC/MS. Batch experiments also were conducted to determine equilibrium capacity of activated carbon for clofibric acid. Preliminary results indicate the occurrence of the selected PPCP contaminants in raw water samples at or near method-detection limits. For batch equilibrium experiments, preliminary results indicate that activated carbon potentially can be used to remove clofibric acid from water. More research is needed to develop rapid and reliable methods for PPCP analysis and to determine the effectiveness of treatment processes for removal of PPCP contaminants in water.

Determination of rice herbicides, their transformation products and clofibric acid using on-line solid-phase extraction followed by liquid chromatography with diode array and atmospheric pressure chemical ionization mass spectrometric detection

A simultaneous method for the trace determination of acidic, neutral herbicides and their transformation products in estuarine waters has been developed through an on-line solid-phase extraction method followed by liquid chromatography with diode array and mass spectrometric detection. An atmospheric pressure chemical ionization (APCI) interface was used in the negative ionization mode after optimization of the main APCI parameters. Limits of detection ranged from 0.1 to 0.02 ng/ml for 50 ml of acidified estuarine waters preconcentrated into polymeric precolumns and using time-scheduled selected ion monitoring mode. Two degradation products of the acidic herbicides (4-chloro-2-methylphenol and 2,4-dichlorophenol) did not show good signal response using APCI-MS at the concentration studied due to the higher fragmentor voltage needed for their determination. For molinate and the major degradation product of propanil, 3,4-dichloroaniline, positive ion mode was needed for APCI-MS detection. The proposed method was applied to the determination of herbicides in drainage waters from rice fields of the Delta del Ebro (Spain). During the 3-month monitoring of the herbicides, 8-hydroxybentazone and 4-chloro-2-methylphenoxyacetic acid were successively found in those samples.

Chromatographic resolution of ciprofibrate and interaction of the racemate and both enantiomers with rat liver microsomes in vitro

The enantiomers of ciprofibrate may be achieved by enantioselective HPLC separation of its methylesters using a OD - Daicel column. Ciprofibrates (racemate and both enantiomers) bind to oxidized cytochrome P-450 in rat liver microsomes according type II like aniline or most probably as inversed type I, but less pronounced and with a general shift to the left. Ethylmorphine N-demethylation, ethoxycoumarin and ethoxyresorufin O-deethylation are all inhibited by the ciprofibrates, most effectively ethoxyresorufin O-deethylation by S(-)-ciprofibrate even in microM concentrations. Microsomal luminol and lucigenin amplified chemiluminescence indicating the formation of reactive oxygen species, microsomal hydrogen peroxide formation and NADPH/Fe stimulated lipid peroxidation were inhibited in a concentration dependent manner in concentration ranges between mM and microM. This might be due to distinct scavenger activities of all 3 compounds: the zymosan stimulated chemiluminescence of whole blood was completely inhibited in mM concentrations and influenced significantly down to concentrations of 10 microM, whereas burst and phagocytosis tests with human polynuclear leucocytes were not influenced.

The enantiomeric resolution of ciprofibrate and related compounds by HPLC using chiral stationary phases

The attempted chromatographic resolution of the drug ciprofibrate and a range of related compounds, containing the chiral moiety 2,2-dichlorocyclopropylbenzene, using five different chiral stationary phases is described. Aqueous mobile phases were used throughout and the successful separation of nine out of 12 pairs of enantiomers was achieved. Structures remote from the chiral centre were seen to affect chiral recognition.

[The pharmacokinetics of antilipemic agents. 8. Unequivocal characterization of ciprofibrate-O-beta-d-glucuronide]

After an oral single dose Ciprofibrate (1) is eliminated mainly (greater than 90%) as its glucuronide renally and to a small amount on the biliary route. This conjugate could be extracted out of the urine of volunteers. By methylation of the carboxy group and acetylation of the three hydroxy groups of the glucuronic acid the hydrophobic methyl-(2,3,4-tri-O-acetyl-beta-D-glucopyrano)-uronate was formed. This derivative could be identified unequivocally by HPLC using the reference substance which can be obtained easily. Due to the chirality of 1 its glucuronide and the corresponding hydrophobe derivative (melting range 67-78 degrees C) are a mixture of diastereomeres. The latter could be separated analytically into the diastereomeres using a cyclobond I-column.

Separation and measurement of clofibroyl coenzyme A and clofibric acid in rat liver after clofibrate adminstration by reversed-phase high-performance liquid chromatography with photodiode array detection

A method to identify and quantitate clofibric acid and clofibroyl coenzyme A (CoA) products in rat liver was developed using reversed-phase high-performance liquid chromatography. The system was developed with baseline separation of clofibroyl-CoA from clofibric acid using isocratic elution, with a mobile phase consisting of 52% methanol and 28 mM potassium phosphate buffer (pH 4.2). With this high methanol concentration, the large amount of UV-absorbing materials present in the liver extracts were eluted earlier than the investigated compounds. Clofibroyl-CoA has a characteristic absorbance spectrum with distinct peaks at 260 and 230 nm, while clofibric acid showed only a distinct peak at 230 nm. Using an on-line photodiode array detector, the spectra could be recorded during analysis without interrupting the flow of the mobile phase. This spectral analysis identification possibilities and evaluation of the purity of the chromatographic peaks. In a perchloric extract of rat liver, the recovery of clofibric acid and clofibroyl-CoA added to the liver extract ranged from 70 to 80%. A linear relationship was observed between clofibric acid and clofibroyl-CoA concentration and the area of their peaks in the chromatogram. The detection limit of the method was lower than 5 pmol for both compounds when the absorbance was recorded at 230 nm. The method could be used without modification for the estimation of clofibroyl-CoA and clofibric acid in biological extracts.

The analysis of [14C]clofibric acid glucuronide and [14C]clofibric acid in plasma and urine using high-performance liquid chromatography

A high-performance liquid chromatographic method has been developed for the quantitation of [14C]clofibric acid glucuronide and [14C]clofibric acid using conventional scintillation counting. The assay has a linear relationship between the added and observed ratios of clofibric acid glucuronide: clofibric acid in the range of 0.001-0.6 for plasma and 0.5-100 for urine, and is able to quantitate previously unmeasurable concentrations of clofibric acid glucuronide in plasma.

Predictions of stability in pharmaceutical preparations XIX: Stability evaluation and bioanalysis of clofibric acid esters by high-pressure liquid chromatography

Specific, sensitive, reversed-phase high-pressure liquid chromatographic assays of clofibric acid esters, clofibrate and etofibrate, and their hydrolysis products, clofibric acid and its monoglycolate and nicotinic acid and its monoglycolate, have been developed in aqueous solution and in biological fluids. Sensitivities of 100 ng/ml of injected mobile phase, a 10-fold increase over existing methods, are reported. Plasma concentrations as low as 200 ng/ml can be analyzed easily in the miscible phase after acetonitrile denaturation. The compounds and their products can be extracted with haloalkane solvents. The extracts were evaporated, reconstituted, and assayed in minimal amounts of mobile phase, resulting in sensitivities of 10 ng/ml of plasma. Conditions are presented that minimize interferences with plasma components. The assay was used to determine the stability of the clofibric acid esters in aqueous solutions, to establish log k-pH profiles at various temperatures, and to evaluate Arrhenius parameters. Hydrolysis was by specific acid-base catalysis. The initial product of etofibrate solvolysis at pH greater than 6 is the monoglycol ester of clofibric acid; at pH less than 3, it is the monoglycol ester of nicotinic acid. Clofibric acid esters are highly unstable to mild alkali (1-3 hr at pH 10 and 30 degrees); even in the estimated pH range of maximum stability, they have half-lives of 100-200 days at 30 degrees. They have half-lives of 4-7 min at 37.5 degrees in fresh dog plasma, and data presented indicate that clofibric acid monoglycolate is an initial product of etofibrate solvolysis.

Saliva and plasma levels and plasma protein binding of clofibrinic acid in uremic patients

Clofibrinic acid in saliva and plasma and its plasma protein binding were determined in 18 patients with renal impairment after a single 2-gm dose of clofibrate. A weak but significant correlation (r2 = 0.378; p less than 0.02) between free plasma and saliva levels of clofibrinic acid was found. The free fraction of clofibrinic acid in plasma is higher (p less than 0.02) in long-term hemodialysis patients (0.0915 +/- 0.0141) than in nondialysis patients (0.0715 +/- 0.0143). During dialysis, 2 hemodialysis patients had a free fraction more than twice as high (mean, 0.2083) as that in the other hemodialysis patients who were studied on interdialysis days. These observations suggest that saliva pH determinations are essential for optimal interpretation of saliva to plasma level ratios of weakly acidic drugs and that, during hemodialysis, patients may temporarily be exposed to increased risks of drug toxicity due to rises in free concentrations of drugs.