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1.
Cyanuric acid is a suspected gastrointestinal or liver toxicant in humans. Therefore, determination of trace cyanuric acid is very important, in this work a novel, sensitive, and reliable method was developed using differential pulse polarography. Optimum conditions for analytical determination were found to be at a pH of 9.5, Britton–Robinson at a reduction potential of ?105 mV. Experimental results indicate an excellent linear correlation between the peak current and the concentration in the range of cyanuric acid from 0.5 to 27.0 µM (0.06–3.5 µg mL?1) with a correlation coefficient of 0.997. The limit of detection and limit of quantification were obtained as 0.15 and 0.5 µM (0.02–0.06 µg mL?1), respectively. The proposed method was successfully applied to the determination of cyanuric acid in pool water and in spiked milk. Cyanuric acid level in swimming pool water was found as 2.54 ± 0.47 µg mL?1 (19.7 ± 2.29 µM) in swimming pool water for N = 4 and 95% confidence interval. The recoveries were found to be sufficient. Also, the standard deviation of the data was low which shows high accuracy and precision of proposed differential pulse polarographic method. The influences of some other commonly found inorganic salts on the determination of cyanuric acid were also examined. Some interfering species were eliminated using complexing agents, e.g., EDTA.  相似文献   

2.
An on‐line solid phase extraction method for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry has been described. The procedure is based on the retention of Cu(II) ions at pH 6.0 on a minicolumn packed with Amberlite XAD‐1180 resin impregnated with chrome azurol S. After preconcentration, Cu(II) ions adsorbed on the impregnated resin were eluted by 1 mol L?1 HNO3 solution. Several parameters, such as pH, type of eluent, flow rates of sample and eluent solutions, amount of resin were evaluated. At optimized conditions, for 3.5 min of preconcentration time, the system achieved a detection limit of 1.0 µg L?1, and a relative standard deviation of 1.2% at 0.2 µg mL?1 copper. An enrichment factor of 56‐fold was obtained with respect to the copper determination. The proposed method was successfully validated by the analysis of standard reference material (TMDA 54.4 lake water) and recovery studies. The method was applied to the preconcentration of Cu(II) in natural water samples.  相似文献   

3.
In this work, an analytical methodological study was carried out to determine the antimicrobials sulfamethoxazole and trimethoprim, as well as their metabolites, in hospital effluent. The determinations were conducted by liquid chromatography tandem mass spectrometry using a hybrid triple quadrupole‐linear ion trap mass spectrometer (LC‐QqLIT‐MS). The data acquisition was made in selected reaction monitoring (SRM) mode, in which two SRM transitions were monitored to ensure that the target compounds were accurately identified by the information dependent acquisition (IDA) function. The limits of detection (LOD) and quantification (LOQ) were 0.25 and 0.80 µg L?1 for sulfamethoxazole and 0.15 and 0.50 µg L?1 for trimethoprim. The linear range for the SMX was 0.8–100.0 µg L?1 and TMP was 0.5–100.0 µg L?1 on the basis of six‐point calibration curves generated by means of linear regression analysis. The coefficients of the correlation were higher than 0.999, which ensured the linearity of the method. The average concentration of sulfamethoxazole and trimethoprim found in hospital effluent was 27.8 and 6.65 µg L?1, respectively. The analytical methodology employed allowed two metabolites to be identified, N4‐acetyl‐sulfamethoxazole and α‐hydroxy‐trimethoprim. Fragmentation pathways were proposed.  相似文献   

4.
Simple, rapid, and sensitive spectrophotometric methods have been proposed for the determination of cationic surfactants (CS) as cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium (DTAB), and cetylpyridinium bromide (CPB). The methods are based on the effects of CSs on the complexes of Al3+ and Be2+ with Chrome Azurol S (CAS). The optimum reaction conditions such as CAS concentration, metal ion concentration, and pH have been studied and found to be 2.0 × 10?4 mol L?1 CAS, 0.5 mg L?1 Al3+ or 0.4 mg L?1 Be2+ and pH 5.4. The analytical characteristics of the methods such as limit of detections, limit of quantifications, and linear ranges have been obtained. CTAB, CPB, and DTAB could be determined by the Al–CAS complex in the ranges of 0.50–40.00, 0.20–10.00, and 0.40–10.00 µmol L?1, and for the Be–CAS complex in the ranges of 0.08–5.00, 0.08–3.00, and 0.20–6.00 µmol L?1, respectively. The limit of the detections of the method for the determination of CTAB, CPB, and DTAB for the Be–CAS complex has been found as 0.025, 0.024, and 0.061 µmol L?1, respectively. The interfering effect of some anions and cations was also tested. The method was applied to the determination of CS CTAB in conditioner shampoo and water samples.  相似文献   

5.
Water source and lake landscape position can strongly influence the physico‐chemical characteristics of flowing waters over space and time. We examined the physico‐chemical heterogeneity in surface waters of an alpine stream‐lake network (>2600 m a.s.l.) in Switzerland. The catchment comprises two basins interspersed with 26 cirque lakes. The larger lakes in each basin are interconnected by streams that converge in a lowermost lake with an outlet stream. The north basin is primarily fed by precipitation and groundwater, whereas the south basin is fed mostly by glacial melt from rock glaciers. Surface flow of the entire channel network contracted by ～60% in early autumn, when snowmelt runoff ceased and cold temperatures reduced glacial outputs, particularly in the south basin. Average water temperatures were ～4 °C cooler in the south basin, and temperatures increased by about 4–6 °C along the longitudinal gradient within each basin. Although overall water conductivity was low (<27 µS cm?1) because of bedrock geology (ortho‐gneiss), the south basin had two times higher conductivity values than the north basin. Phosphate‐phosphorus levels were below analytical detection limits, but particulate phosphorus was about four times higher in the north basin (seasonal average: 9 µg l?1) than in the south basin (seasonal average: 2 µg l?1). Dissolved nitrogen constituents were around two times higher in the south basin than in the north basin, with highest values averaging > 300 µg l?1 (nitrite + nitrate‐nitrogen), whereas particulate nitrogen was approximately nine times greater in the north basin (seasonal average: 97 µg l?1) than in the south basin (seasonal average: 12 µg l?1). Total inorganic carbon was low (usually <0·8 mg l?1), silica was sufficient for algal growth, and particulate organic carbon was 4·5 times higher in the north basin (average: 0·9 mg l?1) than in the south basin (average: 0·2 mg l?1). North‐basin streams showed strong seasonality in turbidity, particulate‐nitrogen and ‐phosphorus, and particulate organic carbon, whereas strong seasonality in south‐basin streams was observed in conductivity and dissolved nitrogen. Lake position influenced the seasonal dynamics in stream temperatures and nutrients, particularly in the groundwater/precipitation‐fed north‐basin network. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

6.
In this study the occurrence of diclofenac and sub‐products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC‐DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC‐DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10?3 mol L?1, and phase B was methanol (5 × 10?3 mol L?1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L?1, the LQs, 8.3 and 0.05 µg L?1, and the linear range from 10 up to 2000 µg L?1 and 0.05 up to 10 µg L?1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′‐hydroxy‐diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.  相似文献   

7.
The aim of this study is to investigate the concentrations of U, Th, V, Mo, and Zr in natural waters taken from Turkey. Among these water species, Lake Van is the largest soda lake and the fourth largest closed basin on Earth. The water samples were collected from 51 locations between 2008 and 2009. The inductively coupled plasma‐MS was used for determinations. The obtained U and Zr concentrations are in the range of 37–110 µg L?1 and 17–78 µg L?1 in Lake Van and 0.53–0.81 µg L?1 and 0.15–0.19 µg L?1 in Lake Hazar, respectively. The concentration of uranium in other studied waters varies from the lowest 0.09 µg L?1 in Tigris (Dicle) river to the highest 4.0 µg L?1 in Mediterranean Sea water. Mean Mo and V concentrations in the studied water samples were found to be in ranges of 0.1–17 and 2.7–113 µg L?1, respectively. The obtained highest U concentration in Lake Van correlates with the highest Mo and Zr levels compared to the Lake Hazar and river waters. These results imply that there is a young occurrence of uranium minerals around Lake Van. It is concluded that there is about 50.000 ton of uranium in Lake Van water.  相似文献   

8.
A simple and reliable method for rapid and selective extraction and determination of trace levels of Ni2+ and Mn2+ was developed by ionic liquid (IL) based dispersive liquid–liquid microextraction coupled to flame atomic absorption spectrometry (FAAS) detection. The proposed method was successfully applied to the preconcentration and determination of nickel and manganese in soil, vegetable, and water samples. After preconcentration, the settled IL‐phase was dissolved in 100 µL of ethanol and aspirated into the FAAS using a home‐made microsample introduction system. Injection of 50 µL of each analyte into an air–acetylene flame provided very sensitive spike‐like and reproducible signals. Effective parameters such as pH, amount of IL, volume of the disperser solvent, concentration of the chelating agent, and effect of salt concentration were inspected by a (25‐1) fractional factorial design to identify the most important parameters and their interactions. Under optimum conditions, preconcentration of 10 mL sample solution permitted the detection of 0.93 µg L?1 Ni2+ and 0.52 µg L?1 Mn2+ with enrichment factors 77.2 and 82.6 for Ni2+ and Mn2+, respectively. The accuracy of the procedure was evaluated by analysis of a certified reference material (CRM TMDW‐500, drinking water).  相似文献   

9.
A new sorbent was prepared by loading rhodamine B on Amberlite IR‐120. Various physico‐chemical parameters such as effects of adsorbate concentration, contact time, pH, and temperature on the sorption of the dye have been studied. Thermodynamic parameters (ΔH° and ΔS°) were also evaluated for the sorption of dye. Kinetic studies revealed that the sorption of the dye was best fit for pseudo‐second‐order kinetic. The metal ion uptake in different solvent systems has been explored through column studies. On the basis of distribution coefficient (Kd), some heavy metal ions of analytical interest from binary mixtures have been separated. The limit of detection (LOD) for the Ni2+ and Fe3+ metal ions was 0.81 and 0.60 µg L?1, and the limit of quantification (LOQ) was found to be 2.72 and 2.0 µg L?1. This sorbent has also been successfully applied in the analysis of multivitamin formulation. The applicability of the modified resin in the separation of heavy metals constituting real and synthetic samples has been explored.  相似文献   

10.
A new method for determining lead (Pb) content was developed by dispersive liquid–liquid microextraction based on the solidification of floating organic droplets followed by flame atomic absorption spectrometry. Under optimum conditions, the calibration graph was linear within the Pb content range of 8.43–400 µg L?1 with a detection limit of 2.53 µg L?1. The relative standard deviation for 10 replicate measurements of 20 and 400 µg L?1 of Pb were 3.41 and 2.78%, respectively. The proposed method was assessed through the analysis of certified reference water and recovery experiments.  相似文献   

11.
The present paper proposes the application of multiwalled carbon nanotubes (MWCNTs) as a solid adsorbent for selective separation/preconcentration of silver(I) in water samples prior to flame atomic absorption spectrometry. The procedure is based on the solid phase extraction of Ag(I)–2‐mercaptobenzothiazole chelate on MWCNTs. The elution step is carried out with 5 mL of 2 mol L?1 HNO3 in acetone solution at a flow rate of 1.0 mL min?1. The influences of the various analytical parameters including pH of the solution, eluent type, sample volume, flow rates of eluent, matrix ions were investigated for optimization of the presented procedure. Tests of addition/recovery for analyte ion in real samples were performed with satisfactory results. Preconcentration factor and limit of detection for Ag(I) were 160 and 0.21 µg L?1, respectively. The synthesized MWCNT exhibited excellent stability in eluent solution and its adsorption capacity was 5.4 mg of silver per gram of sorbent. The proposed method was successfully applied to trace silver determination in a variety of environmental water samples.  相似文献   

12.
Soil denitrification in reservoir shoreline wetlands is an important process for removing excess inorganic nitrogen from upland runoff and controlling eutrophication in aquatic ecosystems. As yet, little is known about the influence of vegetation characteristics on the soil denitrification potential in reservoir shoreline wetlands, although vegetation can affect both denitrifying bacteria and soil properties. In this study, we measured the spatial variability of denitrification enzyme activity (DEA) using acetylene block method in shoreline wetlands of the Danjiangkou Reservoir, a water source of the South‐to‐North Water Transfer Project in China. Results indicated that DEA ranged from 0.001 to 2.449 µg N (N2O) g?1 h?1, with a mean of 0.384 µg N (N2O) g?1 h?1. DEA varied significantly among five representative plant communities and the highest DEA (0.248–2.449 µg N (N2O) g?1 h?1) was observed in the Polygonum hydropiper community. Plant biomass and vegetation cover were significantly and positively related to DEA and together explained 44.2% of the total variance. These results suggest that vegetation characteristics should also be considered in assessing soil denitrification capacity and restoring shoreline wetlands for nitrogen pollution removal in the Danjiangkou Reservoir after dam heightening.  相似文献   

13.
The coprecipitation method is widely used for the preconcentration of trace metal ions prior to their determination by flame atomic absorption spectrometry (FAAS). A simple and sensitive method based on coprecipitation of Fe(III) and Ni(II) ions with Cu(II)‐4‐(2‐pyridylazo)‐resorcinol was developed. The analytical parameters including pH, amount of copper (II), amount of reagent, sample volume, etc., were examined. It was found that the metal ions studied were quantitatively coprecipitated in the pH range of 5.0–6.5. The detection limits (DL) (n = 10, 3s/b) were found to be 0.68 µg L?1 for Fe(III) and 0.43 µg L?1 for Ni(II) and the relative standard deviations (RSD) were ≤4.0%. The proposed method was validated by the analysis of three certified reference materials (TMDA 54.4 fortified lake water, SRM 1568a rice flour, and GBW07605 tea) and recovery tests. The method was successfully applied to sea water, lake water, and various food samples.  相似文献   

14.
Biological Degradation of 2,4-Dinitrotoluene in a Continuous Bioreactor and Kinetic Studies Experimental results on the aerobic biological degradation with complete mineralization of 2,4-dinitrotoluene (2,4-DNT) are presented. A culture of Pseudomonas sp. DNT from Spain and Nishino was used. The degradation was examined with batch cultures for the determination of kinetic and stoichiometric coefficients. Further experiments were carried out with a continuous culture in a fixed-bed reactor with recirculation in order to obtain high degradation rates. The reactor was packed with ceramic Raschig rings (55 mL) and had a liquid reaction volume of 160 mL. The minimal salt media from Spanggord et al. with and without (NH4)2S)4 as nitrogen source was used as substrate. 2,4-DNT was the sole source of carbon and energy. From batch experiments a yield coefficient YB/S = (0.30 ± 0.05) g g?1 was calculated from a mass balance of the elements. This result was confirmed by calculations using literature data. Fitting the experimental data to the Monod equation, μmax = 0.1 h?1 and KS = 0.01…0.03 mmol L?1 were obtained. It was demonstrated by batch experiments that 2,4-DNT is not only used as the source of carbon and energy but also as the nitrogen source. In the fixed-bed reactor, a degradation of 92…97% was reached with a maximal 2,4-DNT load of 95 mg L?1 h?1. The rate of continuous degradation could be described by a pseudo-first-order reaction (k = 9.73 h?1). The complete mineralization of 2,4-DNT was verified by the measurement of DOC and the formed nitrite and nitrate. The formed nitrite was nitrified simultaneously. It was demonstrated by these experiments that large scale biological treatment of industrial effluent containing 2,4-DNT may be successful.  相似文献   

15.
This study examines the effect of drawdown on the timing and magnitude of suspended solids and associated phosphorus export from a 12 ha reservoir located in an urbanized watershed in southern Ontario, Canada. Water level in Columbia Lake was lowered by 1·15 m over a 2‐week period in November 2001. The total phosphorus (TP) concentrations ranged from 63 to 486 µg L?1 in Columbia Lake and 71 to 373 µg L?1 at its outflow. All samples exceeded the Provincial Water Quality Objective of 30 µg TP L?1. Outflow concentrations of suspended solids and TP increased significantly with decreasing lake level and were attributed to the resuspension of cohesive bottom sediments that occurred at a critical threshold lake level (0·65 m below summer level). Suspended solids at the outflow consisted of flocculated cohesive materials with a median diameter (D50) of c. 5 µm. Particulate organic carbon accounted for 8·5% of the suspended solids export by mass. A total mass of 18·5 t of suspended solids and 62·6 kg TP was exported from Columbia Lake, which represents a significant pulse of sediment‐associated P to downstream environments each autumn during drawdown. The downstream impacts of this release can be minimized if the water level in Columbia Lake is lowered no more than 0·5 m below summer levels. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

16.
Cadmium (Cd) has become an important heavy metal contaminant in the sediment and seawater along the Bohai Sea and been of great ecological risk due to its toxic effects to marine organisms. In this work, the toxicological effects caused by environmentally relevant concentrations (10 and 40 µg L?1) of Cd were studied in the gill tissues of Manila clam Ruditapes philippinarum after exposure for 24, 48, and 96 h. Both low (10 µg L?1) and high (40 µg L?1) doses of Cd caused the disturbances in energy metabolism and osmotic regulation and neurotoxicity based on the metabolic biomarkers such as succinate, alanine, branched chain amino acids, betaine, hypotaurine, and glutamate in clam gills after 24 h of exposure. However, the recovery of toxicological effects of Cd after exposure for 96 h was obviously observed in clam to Cd exposures. Overall, these results indicated that NMR‐based metabolomics was applicable to elucidate the toxicological effects of heavy metal contaminants in the marine bioindicator.  相似文献   

17.
Ambient concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were measured at 51 sampling points by passive sampling technique in Kocaeli, an important industrial city in Turkey. Samples were analyzed by UV‐spectrophotometry for NO2 and O3 and by ion chromatography for SO2, respectively. Concentrations of SO2, NO2, and O3 were determined to investigate their spatial distribution and source characterization. The sampling campaigns revealed an average concentration of 8 µg/m3 (max. 82 µg/m3) for SO2, and 14 µg/m3 (max. 40 µg/m3) for NO2, in summer; while average winter concentrations were 25 µg/m3 (max. 61 µg/m3) for SO2, and 50 µg/m3 (max. 100 µg/m3) for NO2. The maximum ozone concentrations were determined to be 86 µg/m3 in summer and 61 µg/m3 in winter downwind of the source areas of the precursor pollutant emissions. The results showed that NO2 and SO2 concentrations in industrial and urban areas were two to four times higher compared with rural areas in the summer and winter. In the light of the information obtained from the spatial interpolation of the pollutant concentrations, a selection of appropriate locations for continuous monitoring was suggested according to the European Community (EU) directives.  相似文献   

18.
As basis for the development of a sensitive analytical method for the determination of the insecticide alanycarb, a study of the differential pulse polarographic (DPP) reduction of alanycarb on a dropping mercury electrode (DME) was performed. The pesticide was found to give a single DP peak over the pH range 1.0 to 6.0 and the pH dependency of the peak potential showed a linear segment with a slope of 65.2 mV (at 20°C). For the analytical DPP method running at pH 6.0 (peak at –503.4 mV), the relationship between the peak current and alanycarb concentration was linear in the range of 1.10 to 9.76 μg mL–1 with a detection limit of 0.33 μg mL–1. The proposed method was applied for the determination of alanycarb in spiked dam water and orange juice samples. The recoveries calculated for both types of dam water and orange juice samples spiked with 12.0 μg mL–1 alanycarb were 96.3 and 99.0% with relative standard deviations of 5.2 and 1.3%, respectively. The sufficiently good recoveries and low relative standard deviations for the data reflect the high accuracy and precision of the proposed differential pulse polarographic method. The effects of diverse metal ions and other commonly used pesticides on the determination of alanycarb were also investigated.  相似文献   

19.
In this study, an investigation was carried out into the occurrence of sulfamethoxazole (SMX) and trimethoprim (TMP) in the effluent of the university hospital (HUSM) of the UFSM. The degradation of these antimicrobials by the electrocoagulation (EC) process was also examined, in both the aqueous solution and hospital effluent, and a study was conducted in order to identify the subproducts formed. The experiments were optimized through factorial planning and, also, checked by response surface methodology. The best conditions for EC (achieving 58.0% of chemical oxygen demand (COD) reduction) were obtained by using 13 mA cm?2, 500 mg L?1 of NaCl, and 30 mm of interelectrode distance. The quantification of SMX (27.8 µg L?1) and TMP (6.65 µg L?1) in the hospital effluent, and the identification of the degradation products were carried out through liquid chromatography‐mass spectrometry quadrupole linear and ion trapping with electrospray ionization (LC‐ESI‐MS/MS_QTrap). Removals of 88.0% (degradation only) and 33.0% (adsorption only) were achieved for aqueous solutions of SMX and TMP, respectively, under optimized conditions. In hospital effluent samples, fortified with additions of SMX and TMP, corresponding removals of 16.0% (degradation) and 28.0% (adsorption) were achieved. This suggests that the EC process is efficient in degrading SMX in aqueous solution, although the same was not the case with TMP. The degradation products of SMX were identified (m/z 256.0 and 288.5); however, only the latter is mentioned in the literature. Toxicological aspects were not considered in this study.  相似文献   

20.
Propane biosparging and bioaugmentation were applied to promote in situ biodegradation of 1,4‐dioxane at Site 24, Vandenberg Air Force Base (VAFB), CA. Laboratory microcosm and enrichment culture testing demonstrated that although native propanotrophs appeared abundant in the shallow water‐bearing unit of the aquifer (8 to 23 ft below ground surface [bgs]), they were difficult to be enriched from a deeper water‐bearing unit (82 to 90 feet bgs). Bioaugmentation with the propanotroph Rhodococcus ruber ENV425, however, supported 1,4‐dioxane biodegradation in microcosms constructed with samples from the deep aquifer. For field testing, a propane‐biosparging system consisting of a single sparging well and four performance monitoring wells was constructed in the deep aquifer. 1,4‐dioxane biodegradation began immediately after bioaugmentation with R. ruber ENV425 (36 L; 4 × 109 cells/mL), and apparent first‐order decay rates for 1,4‐dioxane ranged from 0.021 day?1 to 0.036 day?1. First‐order propane consumption rates increased from 0.01 to 0.05 min?1 during treatment. 1,4‐dioxane concentrations in the sparging well and two of the performance monitoring wells were reduced from as high as 1090 µg/L to <2 µg/L, while 1,4‐dioxane concentration was reduced from 135 µg/L to 7.3 µg/L in a more distal third monitoring well. No 1,4‐dioxane degradation was observed in the intermediate aquifer control well even though propane and oxygen were present. The demonstration showed that propane biosparging and bioaugmentation can be used for in situ treatment of 1,4‐dioxane to regulatory levels.  相似文献   

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