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The use of solid-phase microextraction ( SPME) as a nonlethal technique for in vivo sampling of pharmaceutical residue in fish tissue has been documented in the literature. However, there is need to improve its simplicity and robustness for wider applications in the laboratory and field. The objective of this research is to develop and improve the SPME device for sampling of pharmaceuticals in fish tissue. The practical application of the new device was demonstrated in the field where some wild fish ( Esox masquinongy) were caught in the river and sampled by the device. The samples were analyzed using LC coupled with MS/ MS ( LC- MS/ MS). The new in vivo SPME device with a PDMS extraction phase (sorbent) was demonstrated to a robust tool by both experts and nonexpert of the method and it is simpler than the traditional device. The detection limit of the method in gel and fish tissue was 0.01-0.26 ng/g. The interday reproducibility in gel and fish homogenized fish tissue was 8-16% RSD. This study demonstrates that the new device will provide a platform or opportunity for rapid sampling of carbamazepine, diazepam, and nordiazepam in fish muscle with acceptable precision. [ABSTRACT FROM AUTHOR]

The parallel in vivo measurement of chemicals at various locations in living tissues is an important approach furthering our understanding of biological uptake, transportation, and transformation dynamics. However, from a technical perspective, such measurements are difficult to perform with traditional in vivo sampling techniques, especially in freely moving organisms such as fish. These technical challenges can be well addressed by the proposed depth-profiling solid-phase microextraction (DP-SPME) technique, which utilizes a single soft, flexible fiber with high spatial resolution. The analytical accuracy and depth-profiling capability of DP-SPME was established in vitro within a multilayer gel system and an onion artificially contaminated with pharmaceuticals. In vivo efficacy was demonstrated by monitoring pharmaceutical distribution and accumulation in fish muscle tissue. The DP-SPME method was validated against pre-equilibrium SPME (using multiple small fibers), equilibrium SPME, and liquid extraction methods; results indicated DP-SPME significantly improved precision and data quality due to decreased intersample variation. No significant adverse effects or increases in mortality were observed in comparisons of fish sampled by DP-SPME relative to comparable fish not sampled by this method. Consequently, the simplicity, effectiveness, and improved precision of the technique suggest the potential for widespread application of DP-SPME in the sampling of heterogeneous biotic and abiotic systems. [ABSTRACT FROM AUTHOR]

Solid-phase microextraction (SPME) is a promising technique for determining organic contaminants within biotic systems. Existing in vivo SPME-kinetic calibration (SPME-KC) approaches are unwieldy due to the necessity of predetermining a distribution coefficient for the analyte of interest in the tissue and the preloading of a calibrating compound to the fiber. In this study, a rapid and convenient SPME alternative calibration method for in vivo analysis, termed SPME-sampling rate (SPME-SR) calibration, was developed and validated under both laboratory and field conditions to eliminate such presampling requirements. Briefly, the SPME probe is inserted into tissue, in this study fish dorsal-epaxial muscle, for 20 min allowing the concentrations of target analytes in the fish muscle to be determined by the extracted amount of analyte and the predetermined sampling rates. Atrazine, carbamazepine, and fluoxetine were detected nonlethally in the low ppb levels within fish muscle, with both laboratory and field-derived results obtained by in vivo SPME-KC comparable (within a factor of 1.27) to those obtained by lethal sampling followed by tissue liquid extraction. The technique described in this study represents an important advance which broadens the application of SPME in vivo sampling technology. [ABSTRACT FROM AUTHOR]

Solid-phase microextraction (SPME) coupled to liquid chromatography with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been widely used to analyze biological fluids, tissues, and environmental matrixes for a variety of organic compounds including pharmaceuticals. However, effects of the sample matrix coextracted by SPME on tandem mass spectrometry analysis have not been systematically investigated. In this study, we characterized the complexity of matrix effects (ME) by analyzing SPME extracts of fish muscle and brain tissue, blood, and bile, as well as tap water, surface water, and the influent and effluent from a wastewater treatment plant. Significant enhancement or suppression of ionization (>15%) was observed with all biological and environmental samples. Intrasample ME variability was assessed through comparison of multiple samples from the same sample matrix, while intersample variability between different experimental subjects or varying sample treatment, storage, and sampling conditions were evaluated. To correct for ME, an isotopic internal standard (IIS) method was developed, with the strengths and limitations of the approach discussed. This study provides a framework for applying SPME within complex sample systems where the influences of ME are inevitable, thus ensuring more accurate quantitation of analytes during biological and environmental analysis. [ABSTRACT FROM AUTHOR]

Rate and equilibrium constants of weak noncovalent molecular interactions are extremely difficult to measure. Here, we introduced a homogeneous approach called equilibrium Pre-equilibrium solid-phase microextraction (PE-SPME) has attracted considerable research attention due to shorter sampling times and better temporal resolution than afforded by equilibrium SPME (E-SPME). However, the calibration of PE-SPME is often time-consuming and requires deuterated calibrants, which if available, are often expensive. To address these challenges, we propose a simple but versatile kinetic calibration method, in which nonisotopic (label-free) compounds of interest can supplant the use of deuterated analogues, and the need to determine partitioning coefficients inherent to earlier procedures has been eliminated. Using this approach, both free and total concentrations of analytes can be simultaneously measured within complex sample systems with high accuracy and precision. This calibration method was validated against established E-SPME and solid-phase extraction techniques through the measurement of selected pharmaceuticals in progressively complex matrixes including inorganic buffers, fish blood, and municipal wastewater effluents. This calibration approach may significantly improve time and cost-effectiveness, while improving the application of the SPME approach within highly dynamic systems. [ABSTRACT FROM AUTHOR]

To address the challenge of measuring real-time analyte concentrations within dynamic systems, the temporal resolution of the solid-phase microextraclion (SPME) approach has been investigated. A mass-uptake model for SPME within a dynamic system was developed and validated, with experimental factors affecting the temporal resolution (sampling time, agitation, SPME fiber dimensions, sample concentration and change rate, and instrument sensitivity) characterized. Calibration methods for time-resolved sampling in a dynamic system were compared. To demonstrate the efficacy of time-resolved SPME, this approach was successfully applied to investigate the binding kinetics between plasma proteins and pharmaceuticals, which verified a decrease in free pharmaceutical concentrations over time in the presence of bovine serum albumin. The current study provides the theoretical and logistical framework for applying SPME to the real-lime measurement of dynamic systems, facilitating future SPME applications such as in vivo metabolomic studies. [ABSTRACT FROM AUTHOR]

The space-resolved solid-phase microextraction (SR-SPME) technique was employed to study the tissue-specific bioconcentration of pharmaceuticals in live fish. The segmented design of the SPME fibers allowed for the simultaneous determination of pharmaceutical residues in fish dorsal-epaxial muscle and adipose tissue with a single SPME fiber. The miniaturized fiber endowed the technique with high spatial resolution allowing for quantification of analytes within adjacent, relatively small tissues of immature rainbow trout. The pre-equilibrium sampling and kinetic calibration approach yielded efficient and accurate quantitation of pharmaceuticals in fish tissue. The ability of the SPME method to repeatedly sample the same fish circumvents problems arising from interanimal variation, thus improving the precision of generated bioconcentration kinetic profiles. In vivo monitoring with SR-SPME was validated with in vitro liquid extraction of tissue samples using methanol. Of the nine compounds evaluated, five (atrazine, gemfibrozil, carbamazepine, ibuprofen, and fluoxetine) bioconcentrated in adipose and muscle tissue over the eight exposure days. Although the accumulation of analytes in both tissues was positively correlated, each compound partitioned with differing affinities as modified by their hydrophobicity and unique molecular structure. Water samples analyzed using the SPME technique yielded results similar to those determined by solid-phase extraction (SPE); however, SPME was more rapid and operationally much simpler. This study illustrates the application conditions for in situ SR-SPME while demonstrating the potential of these miniaturized SPME fibers for simultaneous in vivo repeated sampling of multiple tissues. [ABSTRACT FROM AUTHOR]

Antidepressants are a widely prescribed group of pharmaceuticals that can be biotransformed in humans to biologically active metabolites. In the present study, the distribution of six antidepressants (venlafaxine, bupropion, fluoxetine, sertraline, citalopram, and paroxetine) and five of their metabolites was determined in a municipal wastewater treatment plant (WWTP) and at sites downstream of two WWTPs in the Grand River watershed in southern Ontario, Canada. Fathead minnows (Pimephales promelas) caged in the Grand River downstream of a WWTP were also evaluated for accumulated antidepressants. Finally, drinking water was analyzed from a treatment plant that takes its water from the Grand River 17 km downstream of a WWTP. In municipal wastewater, the antidepressant compounds present in the highest concentrations (i.e., >0.5 µg/L) were venlafaxine and its two demethylation products, O- and N-desmethyl venlafaxine. Removal rates of the target analytes in a WWTP were approximately 40%. These compounds persisted in river water samples collected at sites up to several kilometers downstream of discharges from WWTPs. Venlafaxine, citalopram, and sertraline, and demethylated metabolites were detected in fathead minnows caged 10 m below the discharge from a WWTP, but concentrations were all <7 µg/kg wet weight. Venlafaxine and bupropion were detected at very low (<0.005 µg/L) concentrations in untreated drinking water, but these compounds were not detected in treated drinking water. The present study illustrates that data are needed on the distribution in the aquatic environment of both the parent compound and the biologically active metabolites of pharmaceuticals. Environ. Toxicol. Chem. 2010;29:79–89. © 2009 SETAC [ABSTRACT FROM AUTHOR]

Previous field studies utilizing solid-phase microextraction (SPME) predominantly focused on volatile and semivolatile compounds in air or water. Earlier in vivo sampling studies utilizing SPME were limited to the liquid matrix (blood). The present study has expanded the SPME technique to semisolid tissues under laboratory and field conditions through the investigation of both theoretical and applied experimental approaches. Pre-equilibrium extraction and desorption were performed in vivo in two separate animals. Excellent linearity was found between the amounts extracted by SPME from the muscle of living fish and the waterborne concentrations of pharmaceuticals. A simple SPME method is also described to simultaneously determine free and total analyte concentrations in living tissue. The utility of in vivo SPME sampling was evaluated in wild fish collected from a number of different river locations undervarying degrees of influence from municipal wastewater effluents. Diphenhydramine and diltiazem were detected in the muscle of fish downstream of a local wastewater treatment plant Based on this study, SPME demonstrated several important advantages such as simplicity, sensitivity, and robustness under laboratory and in vivo field sampling conditions. [ABSTRACT FROM AUTHOR]

While recent evidence indicates that the generation of reactive oxygen species (ROS) and associated oxidative damage are frequently observed in fish populations with exposure to pulp and paper mill effluents, the potential for ROS generation from municipal sewage effluents has not been addressed. This study investigates the utility of measures of oxidative stress in delineating the effects of both pulp and paper mill and municipal sewage discharges. Longnose sucker (Catostomus catostomus) were collected below three pulp and paper mill and two municipal sewage effluent discharges over a 3-year period within the Wapiti and Athabasca River systems in northern Alberta. Biochemical responses in longnose sucker varied between the two rivers systems, with more pronounced changes occurring within the Wapiti River. Of the suite of biochemical parameters examined, fatty acyl-CoA oxidase (FAO) activity was the most sensitive indicator of pulp and paper mill exposure, but was only infrequently induced with exposure to municipal sewage effluent. Hepatic and gonadal 2-thiobarbituric acid reactive substances, lipid hydroperoxides, and hepatic free iron were less consistently elevated with exposure to pulp and paper mill effluent than FAO activity, and were also only infrequently altered with sewage effluent exposure. Hepatic ascorbic acid, liver somatic index, and condition factor were consistently altered with exposure to both sewage and pulp and paper mill effluents. While specific biochemical and organismal responses varied with effluents and time, the collective suite of oxidative stress endpoints proved to be useful tools in identifying relative influences of municipal sewage and pulp and paper mill effluent on fish populations in adjacent receiving waters. [Copyright &y& Elsevier]

The accurate measurement of free analyte concentrations within complex sample matrixes by pre-equilibrium solid-phase microextraction (SPME) has proven challenging due to variations in mass uptake kinetics. For the first time, the effects of the sample binding matrix and tortuosity on the kinetics of analyte extraction (from the sample to the SPME fiber) are demonstrated to be quantitatively symmetrical with those of the desorption of preloaded deuterated standards (from the fiber to the sample matrix). Consequently, kinetic calibration methods can be employed to correct for variation in SPME sampling kinetics, facilitating the application of pre-equilibrium SPME within complex sample systems. This approach was applied ex vivo to measure pharmaceuticals in fish muscle tissues, with results consistent with those obtained from equilibrium SPME and micro dialysis. The developed method has the inherent advantages of being more accurate, precise, and reproducible, thus providing the framework for applications where rapid measurement of free analyte concentrations (within complicated sample matrixes such as biological tissues, sediment, and surface water) are required. [ABSTRACT FROM AUTHOR]

Abstract: Highly entangled TiO2 nanowires were directly synthesized by hydrothermal growth on Ti substrates at 180°C utilizing various organic solvents to oxidize Ti. The growth mechanism, microstructure and phase transition of TiO2 nanowire membranes were investigated in detail. TiO2 nanowires, with diameters of 10–20nm and lengths up to 100μm, show a phase transition from Type-B to anatase by annealing at 700°C. Robust, free standing TiO2 nanowire membranes with millimeter level thickness can be cleaved from Ti substrates or directly prepared from thin Ti foils. These porous TiO2 membranes, while effective for mechanical microfiltration, can also photocatalytically degrade pharmaceuticals such as trimethoprim under UV irradiation. [Copyright &y& Elsevier]

Nitrite is a common additive used during meat curing to prevent microbial contamination and retain an attractive red color in the product. However, the effects of nitrite on Fenton reactions catalyzed by free iron in meat products are not well understood, although such processes can induce protein oxidation and nitration, affecting the nutritional and aesthetic quality of meat products. This contribution reveals the mechanism through which nitrite affects Fenton reactions that generate reactive nitrogen and oxygen species by increasing the availability of Fe 3+ , facilitating its reduction and stabilizing Fe 2+ , and accelerating Fe 3+ /Fe 2+ cycling, leading to exacerbated oxidative and nitrosative stress on proteins, with implications not only for meat processing but also in many biological and environmental processes due to the ubiquitous presence of iron, hydrogen peroxide, and nitrite in nature.