ABSTRACT
A água utilizada em serviços de hemodiálise passa por um sistema de tratamento a fim de garantir que os parâmetros microbiológicos e físico-químicos estejam adequados e proporcionem segurança ao paciente. Este trabalho avaliou a qualidade da água antes e após esta passar por sistema de tratamento em dois serviços (A e B) de hemodiálise em Santarém. Foram coletadas amostras de água em três pontos: Ponto 1 (P1) após saída do poço, Ponto 2 (P2) na saída do tratamento e Ponto 3 (P3) na máquina de hemodiálise. Testes microbiológicos e físico-químicos foram realizados e os resultados mostraram que não houve crescimento de coliformes totais e Escherichia coli nas amostras. No serviço A, houve contaminação por bactérias heterotróficas em 87% das amostras, destas, 27% ocorreram no P3. O pH mostrou-se menor que 6,0 no P1 nos dois serviços, normalizando os seus valores no P3. No serviço A, concentrações superiores ao recomendado de alumínio e nitrato foram verificadas em 100% das amostras coletadas no P1, os valores foram normalizados na saída do tratamento (P2). A pesquisa demonstrou que, para os parâmetros estudados, a qualidade da água, após passar por sistema de tratamento, é satisfatória, com exceção das bactérias heterotróficas no serviço A. (AU)
The water used in hemodialysis services goes through a treatment system in order to ensure that the microbiological and physicochemical parameters are adequate and provide safety to the patient. This work evaluated the quality of water before and after it went through a treatment system in two hemodialysis services (A and B) in Santarém. Water samples were collected at three points: Point 1 (P1) after leaving the well, Point 2 (P2) leaving the treatment and Point 3 (P3) on the hemodialysis machine. Microbiological and physical-chemical tests were performed and the results showed no growth of total coliforms and Escherichia coli in the samples. In service A, there was contamination by heterotrophic bacteria in 87% of the samples, 27% of which occurred in P3. The pH was less than 6.0 in P1 in both services, normalizing its values in P3. Service A, concentrations higher than the recommended amount of aluminum and nitrate were verified in 100% of the samples collected in P1, the values were normalized at the end of the treatment (P2). The research demonstrated that, for the studied parameters, the water quality, after going through a treatment system, is satisfactory, with the exception of heterotrophic bacteria in service A. (AU)
Subject(s)
Colimetry/methods , Water Samples , Renal Dialysis , Water Treatment PlantsABSTRACT
A novel method for accurate,fast and sensitive detection of pesticides such as imidacloprid,isocarbophos,phoxim,dursban,imidacloprid,pyridaben and avermectin in environmental water samples has been developed by using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with high performance liquid chromatography with ultraviolet detection (HPLC-UV).The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents,ultrasonic time,ionic strength and extraction time were investigated.Under the optimized extraction conditions,the linearity for the detection of six pesticides in the concentration range of 10-600 μg/L was obtained with limits of detections (LODs) of 0.8-3.1 μg/L and relative standard deviations (RSDs) of 4.7％-11.3％.UA-DLLME method exhibited strong enrichment ability for the six pesticides,and the enrichment factor (EFs) were ranged from 58 to 187.This method had perfect linearity,precision and recovery results,and showed obvious advantages and practicality comparing the previously reported methods.
ABSTRACT
Fe3O4-grafted nitrogen-doped graphene (Fe3O4/N-G) nanomaterials were synthesized by chemical co-precipitation method, and its adsorption properties were discussed preliminarily.It was demonstrated that the adsorption of parachlormetaxylenol on Fe3O4/N-G was not limited to uniform monolayer adsorption and the adsorption kinetic followed the pseudo-second-order kinetic mode.Then, an ultrasound-assisted magnetic solid-phase extraction with Fe3O4/N-G as the magnetic adsorbent has been developed for the determination of four compounds including triclosan, chloroxylenol, hexachlorobenzene and 2,2′,4,4′,5,5′-hexachlorobiphenyl in environmental water samples, in combination with gas chromatography coupled to tandem mass spectrometry.Several factors related to extraction efficiencies, such as the amount of adsorbent, extraction time, sample pH and desorption conditions were investigated.The proposed preparation procedure was as follows: 6.0 mg of Fe3O4/N-G was dispersed into 100 mL of water sample under ultrasound.After 15 s, the Fe3O4/N-G carrying four compounds was separated from the water sample by an external magnetic field.Then, the targets were eluted from Fe3O4/N-G with 3 mL of ethanol and 2 mL of dichloromethane, sequentially.Finally, the eluent was dried under a mild stream of nitrogen and reconstituted with methanol and dichloromethane (1∶1, V/V) for the subsequent GC-MS/MS analysis.Under the optimized condition, an excellent linearity was observed in the range of 0.1-10 ng/L for the four compounds, with the correlation coefficients ranging from 0.9983 to 0.9999.The limits of detections (S/N=3) ranged from 0.05 to 0.6 ng/L and the limits of quantity (S/N=10) ranged from 0.2 to 2.4 ng/L.The mean recoveries at three spiked levels ranged from 68.2% to 99.6%.The relative standard deviations (RSDs) of intraday and interday were in the range of 3.3%-6.9% and 3.4%-9.4% (n=6), respectively.The proposed method was demonstrated to be simple and feasible for the trace analysis of antimicrobial agents and organochlorine contaminants in environmental water samples.
ABSTRACT
A method was developed for determination of 12 kinds of phosphate compounds in water and sediment by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) coupled with solid phase extraction (SPE) and ultrasonic extraction.The water samples were concentrated by HLB solid-phase extraction (SPE) column and eluted twice with ethyl acetate, ultrasonic solvent extraction for sediment samples and then repeated the operation of water samples after diluted with deionized water.The sample were separated on a ZORBAX Eclipse Plus C18 (150 mm × 2.1 mm, 3.5 μm) column by a gradient elution with 0.2% formic acid aqueous solution and methanol as the mobile phase.Ion mode analysis was monitored by high performance liquid chromatography mass spectrometer (MRM).The target compounds were quantified by external standard method.At the spiked levels (0.05, 0.1 and 0.5 μg/L), the average recoveries of 12 kinds of OPEs in water samples ranged from 66.4% to 115%, except for TMP (28.5%-47.8%) and TEHP (22.4%-73.8%).The relative standard deviation RSD (n=3) was 0.5%-9.09%, and the method quantification (MOQ) was 0.001-0.05 μg/L, However at the spiked levels of 5, 10 and 50 μg/kg, the average recoveries of 12 kinds of OPEs in sediment samples ranged from 65.4% to 120.0%, except for TMP (35.7%-44.9%) and TCEP (31.2%-48.9%).The relative standard deviation RSD (n=3) was 0.01%-9.54%, and the MOQ for sediment was 0.02-2.0 μg/kg dw.Based on the above methods, the detection and analysis of the targets in the water and sediments samples of Taihu Lake were carried out.The results showed that the concentrations of ΣOPEs were 0.1-1.7 μg/L and 8.1-420 μg/(kg dw), respectively.
ABSTRACT
A method of metal organic nanotubes-based dispersive solid phase extraction-gas chromatography-tandem mass spectrometry was developed for sensitive analysis of polychlorinated biphenyls in environmental water samples.Related important factors influencing enrichment efficiency, such as ionic strength, extraction time and amount of adsorbent, were investigated.Response surface methodology was used to optimize these factors in detail.Under the optimal conditions such as 4.92% (w/V) NaCl, 4.5 min of extraction time, 62.5 mg of adsorbent, and n-hexane as desorption solvent, wide linearity (2-1000 ng/L or 5-1000 ng/L), and low limits of detection (0.26-0.82 ng/L) were achieved.The intra-day and inter-day relative standard deviations were 0.8%-5.5% (200 ng/L, n=6)and 2.7%-7.4% (200 ng/L, n=6), respectively.Finally, this method was successfully applied to the sensitive analysis of 6 kinds of PCBs in environmental water samples, with satisfactory recoveries of 78.9%-113.3%.
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A method for rapid determination of semicarbazide in water by hydrophilic interaction chromatography-quadrupole / electrostatic field orbitrap high resolution mass spectrometry was developed. The sample was extracted with acetonitrile after 0. 1 mol/ L NaOH was added in the sample and then excessive amounts of Na2 SO4 was added to stratify acetonitrile from the mix solution. The acetonitrile extraction solution was dehydrated with anhydrous sodium sulfate. The preparation was separated by an amide column using as hydrophilic interaction column, and gradient elution program was employed by using water and acetonitrile containing 0. 1% formic acid as mobile phase, then it was detected in positive and selected ion monitoring mode by a quadrupole / electrostatic field orbitrap high resolution mass spectrometry. Internal standard method was used for quantitative analysis. The linear correlation coefficient of semicarbazide was 0. 997 in the concentration range of 0. 2 -20 μg / L under the optimal conditions. The limit of detection was 0. 09 μg / L, while the limit of quantitation was 0. 30 μg / L. The recoveries were 82. 3% to 92. 0% , and the relatively standard deviations were less than 7. 6% at the spiked levels of 0. 5, 1. 0 and 5. 0 μg / L using river water and sea water as blank samples. The developed method is suitable for the analysis of trace semicarbazide in environment water samples.
ABSTRACT
Based on microfabrication technology and electrochemical modification method, a micro electrochemical sensor for nitrate ( NO-3 ) determination was developed. A micro sensor chip with working electrode and counter electrode was used as the signal convertor of the sensor. The area of the micro working_electrode was only 1 mm2 . As an electrocatalysis sensitive material, copper was electrodeposited onto the working electrode by square_wave pulse current electrodeposition method. The morphologies and components of freshly deposited materials were examined by scanning electron microscopy ( SEM ) and X_ray diffraction ( XRD) to explore key factors that affected the electrocatalytic ability of the deposited copper layer for reducing nitrate ions. The experimental results revealed that under the optimal conditions, the deposited copper layer was macroporous and had a larger effective surface area that could serve as a more effective electrocatalyst in facilitating nitrate reduction. Electrochemical response of the macroporous copper layer was characterized by linear sweep voltammetry in acidic supporting electrolytes ( pH=2 ) . The electroanalytical results showed that the modified microsensor had marked sensitivity for standard nitrate samples within the concentration range from 12. 5 to 3000 μmol/L (in the range of 12. 5-200 μmol/L yielded straight line:y1=-0. 1422x-10. 326, R12=0. 9976, while in the range of 200-3000 μmol/L yielded straight line: y2=-0. 0984x-22. 144, R22=0. 9927) with a detection limit of 2 μmol/L (S/N=3). The developed electrochemical microsensor was also employed for nitrate determination in water samples collected from lakes and rivers near the city of Beijing. The results were in good agreement with the data given by qualified water quality detection institute, with the deviations from 3 . 9% to 15 . 4%.
ABSTRACT
The performed investigations are concerned on the estimation of extraction properties of copolymer styrenedivinylbenzene (SDB-1) adsorbent and four chemically bonded silica gel materials: octadecyl (C18), octyl (C8), phenyl (C6H5), cyclohexyl (C6H11) for the solid phase extraction of bezafibrate (hypolipidaemic compound) from the model solutions and river water samples. Extraction conditions such as solvent selection, their volumes and water samples pH were found to have significant influence on extraction efficiency of the studied compound. The effect of water matrix on extraction efficiency was checked too. It was found that the best extraction efficiency of bezafibrate from water sample was obtained using bonded silica-octadecyl gel sorbents and polymer material. The presence of drug in elutes was detected by spectrophotometric (measurement of absorbance at 230 nm) and HPLC-UV methods. Under optimal conditions, recoveries of the pharmaceutical were higher than 80 %. The precision of the novel extraction procedures, calculated as coefficient variation (CV %), ranged from 0.008 to 0.018 % for the all tested sorbents.