Low environmental levels of neuro-active pharmaceuticals alter phototactic behaviour and reproduction in Daphnia magna

Assessing the risks of emerging contaminants, such as pharmaceuticals in the environment requires an understanding of their exposure regime and their effects at environmentally relevant concentrations across species. Daphnia magna represents an excellent invertebrate model species to study the mode of action of emerging pollutants, allowing the assessment of effects at different biological levels. The present study aims to test the hypothesis that different families of neuro-active pharmaceuticals at low environmentally relevant concentrations may lead to similar phenotypic responses in D. magna. Phenotypic traits included reproduction and behavioural responses. Selected pharmaceuticals were carbamazepine, diazepam and propranolol, three widely prescribed compounds, already detected at considerable levels in the environment (ng to few μg/L). Fluoxetine was also included in behavioural assays. The three tested neuro-active pharmaceuticals were able to enhance reproduction at 1ng/L of propranolol, 0.1μg/L of diazepam and 1μg/L of carbamazepine. Fluoxetine, carbamazepine and diazepam increased positive phototactic behaviour at concentrations ranging from 1, 10 and 100ng/L, respectively. Reported responses were nonmonotonic, which means that eco-toxicity testing of pharmaceuticals need to assess effects at the ng/L range.

Removal of trace organic chemical contaminants by a membrane bioreactor

Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.

Validation and use of in vivo solid phase micro-extraction (SPME) for the detection of emerging contaminants in fish

A variety of emerging chemicals of concern are released continuously to surface water through the municipal wastewater effluent discharges. The ability to rapidly determine bioaccumulation of these contaminants in exposed fish without sacrificing the animal (i.e. in vivo) would be of significant advantage to facilitate research, assessment and monitoring of their risk to the environment. In this study, an in vivo solid phase micro-extraction (SPME) approach was developed and applied to the measurement of a variety of emerging contaminants (carbamazepine, naproxen, diclofenac, gemfibrozil, bisphenol A, fluoxetine, ibuprofen and atrazine) in fish. Our results indicated in vivo SPME was a potential alternative extraction technique for quantitative determination of contaminants in lab exposures and as well after exposure to two municipal wastewater effluents (MWWE), with a major advantage over conventional techniques due to its ability to non-lethally sample tissues of living organisms.

Effects of sorption on the rejection of trace organic contaminants during nanofiltration

Understanding the removal of trace organic contaminants is critical for membrane applications in water recycling. This study investigates the relationship between trace contaminant sorption and their rejection by nanofiltration (NF) membranes. A mass balance is developed that quantitatively links the rejection decline over time seen with some sorbing compounds to the total mass found sorbed on the membrane. The sorbed mass of perfluorooctane sulfonamide (FOSA) and fluoxetine evaluated from the mass balance agreed to within approximately 30% of the quantity analytically determined via extraction. Static sorption experiments show that sorption takes place predominantly within the polyamide separating layer of the membrane. Finally, the relationship between the steady-state rejection and sorption tendency of ten trace organic compounds is elucidated. A greater tendency to sorb results in lower steady-state rejection, both when comparing compounds of similar size, as well as when comparing the same compound under different conditions. As a result, a major finding is that in the presence of competitive sorption, that is, the presence of other trace organic compounds in the membrane matrix, some compounds sorb less and are therefore rejected more than when these compounds are alone in the feed. At no point during experimentation was any effect on the water flux observed.

Enantiomeric Separation of Fluoxetine Derivatives on Polysaccharide-Based Chiral Columns

A high performance liquid chromatography (HPLC) method employing amylose-based chiral columns (Chiralpak AD-RH and Chiralpak AD) and cellulose-based chiral columns (Chiralcel OD) as chiral stationary phases have been developed for the enantiomeric separation of fluoxetine (FLX) derivatives. The FLX was derivatized with 4-(N-chloroformylmethyl-N-methyl)amino-7-nitro-2,1,3-benzoxadiazole (NBD-COCl) and 4-(N-chloroformylmethyl-N-methyl)amino-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole (DBD-COCl), respectively. Influence of the mobile phase composition and column temperature on the enantioseparation was discussed during the separation. On the basis of separation of derivatized FLX enantiomers, the paper also discussed the separation mechanism on the chiral stationary phases used.

Development of an improved heated interface for coupling solid-phase microextraction to high-performance liquid chromatography

The aim of the study described in this report has been the development and the evaluation of a new improved interface to be operated under continuous heating, for on-line coupling solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC). Heating is desirable to increase desorption rate and decrease carryover. The results obtained have been compared with that obtained by off-line desorption and online desorption without heating. The SPME-HPLC interface described here has an inner volume of 60 microL, fixation for infinite points and a novel leak less sealing system. When the heating system was used, the area values were almost 10-fold higher than that obtained using the off-line mode. The obtained chromatograms showed an increasing of the area and height of chromatographic peaks and proved the excellent performance and reproducibility of the interface developed in this work.

Infinite enantiomeric resolution of basic compounds using highly sulfated cyclodextrin as chiral selector in capillary electrophoresis

Four chiral basic analytes, namely methadone, fluoxetine, venlafaxine, and tramadol, were selected as model compounds for investigating their stereoselective separation with highly sulfated gamma-cyclodextrin (HS gamma-CD) by capillary electrophoresis (CE)-UV and CE-mass spectrometry (MS). At high concentration of chiral selector, the preferentially bonded enantiomer migrated faster in the anodic mode to the detector and high resolutions were obtained for all analytes. In the cathodic mode, at lower highly sulphated cyclodextrin (HS-CD) concentration, basic compounds could be detected, with the weakly bonded enantiomer migrating first (enantiomeric migration order inversion). It was also then possible, at intermediate HS-CD concentration, that only one enantiomer migrated to the detector as cation while the other enantiomer complexed with the CD was negatively charged and presented an opposite mobility. The latter never reached the detector achieving a perfect enantiomeric selectivity. Infinite chiral resolutions were thus achieved by CE-UV as well as by CE-electrospray ionisation (ESI)-MS where concentrations of HS-CD were adapted according to the negative contribution of the nebulization gas pressure of the interface.

Enantiomeric separation and quantification of fluoxetine (Prozac) in human plasma by liquid chromatography/tandem mass spectrometry using liquid-liquid extraction in 96-well plate format

Fluoxetine (Prozac) is currently one of the widely prescribed selective serotonin reuptake inhibitors (SSRIs) for the treatment of depression. A high-throughput sample preparation procedure using liquid-liquid extraction (LLE) in a 96-well plate format in conjunction with liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed and validated for quantification of fluoxetine enantiomers in human plasma. After addition of internal standard and ammonium hydroxide, samples were extracted with ethyl acetate. The organic extract was evaporated to dryness and reconstituted in methanol. Where possible, sample transfer and LLE steps were automated using a Tomtec Quadra 96 workstation. Adequate separation of fluoxetine enantiomeric pairs (resolution of 1.17) was achieved on a vancomycin column eluted with methanol containing 0.075% (by weight) ammonium trifluoroacetate. A triple quadrupole mass spectrometer, operated in the multiple reaction monitoring mode at m/z 310-->44 for fluoxetine enantiomeric pairs and m/z 287-->241 for oxazepam (internal standard), was used. Analysis was performed in the positive ion mode using atmospheric pressure chemical ionization (APCI). The standard curve range was 2.0-1000 ng/mL for each fluoxetine enantiomer. The intra- and inter-day precision and accuracy of the quality control (QC) samples were <12.5% (CV) and <13.6% (CV), respectively, for each fluoxetine enantiomer; the correlation coefficient was >0.990. Method ruggedness was demonstrated by the reproducible performance of the assay during a three-day validation period.

Simultaneous determination of human plasma levels of four selective serotonin reuptake inhibitors by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatography (HPLC) method with fluorimetric detection, which allows the simultaneous determination of plasma concentrations of four selective serotonin reuptake inhibitors (SSRIs) is presented. Fluvoxamine, paroxetine, sertraline, and fluoxetine were extracted from plasma with ethyl acetate and then derivatized with dansyl chloride. The analytes were separated using Hypersyl ODS C18 (5 microm) 250 x 4.6 mm column (ThermoQuest, Runcorn, UK). For continuous gradient separation, the mobile phase consists of two eluents, acetonitrile and potassium phosphate buffer (10 mmol/L, pH 7.2) at total flow rate of 1.5 mL/min. Detection was carried out at lambda exc = 366 nm and lambda em = 490 nm. The authors found recoveries of 90% to 95% for fluvoxamine, 94% to 100% for paroxetine, 88% to 95% for sertraline, 93% to 100% for fluoxetine, and 97% to 100% for internal standard (nortriptyline). Imprecision of the method ranged from 2.5% to 8.9%. The assay was linear from 10 to 1500 ng/mL for sertraline, and from 5 to 1500 ng/mL for the other drugs. The authors conclude that this method is suitable for monitoring antidepressant therapy. In addition, the authors report the effects of adding paroxetine to fluvoxamine on plasma levels in a group of patients in combined drug therapy.

Simultaneous quantification of fluoxetine, norfluoxetine, and desipramine using gas chromatography with nitrogen-phosphorus detection

The combination of fluoxetine (FLU) and desipramine (DMI) has been reported to be useful for the treatment of depression, and these drugs are also known to undergo a metabolic drug-drug interaction because of their effects on cytochrome P-450 2D6. A procedure that separates these two drugs and norfluoxetine (NFLU), the N-demethylated metabolite of FLU, and that allows simultaneous quantification of their levels would be of value and has been developed in our laboratories. The procedure involves an initial extraction into ethyl acetate after basification of the homogenate. The organic phase is retained and taken to dryness; the residue is reconstituted in water and acetylated with acetic anhydride under slightly basic conditions. Ethyl acetate is then used to extract the acetylated compounds from the aqueous medium. The organic layer is taken to dryness and the residue reconstituted in toluene. An aliquot of the solution in toluene is injected directly into a gas chromatograph equipped with a nitrogen-phosphorus detector, a fused silica capillary column, and an integrator/printer. Maprotiline is added to the initial homogenate and carried through the procedure as the internal standard. The assay is rapid and sensitive and has been applied successfully to liver and brain tissue taken from rats treated with FLU, DMI, or the combination.