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1.
Marina Sierra-Rodero Juan Manuel Fern��ndez-Romero Agustina G��mez-Hens 《Mikrochimica acta》2011,173(1-2):11-17
The effect of thiol compounds on the kinetics of the aggregation of gold nanoparticles in the presence of the cationic surfactant cetyltrimethyl ammonium bromide has been studied. It was applied to the determination of N-acetylcysteine using the stopped-flow mixing technique along with light scattering detection. The signal obtained was measured after about 5?s, and gave the analytical information for a calibration graph in the concentration range from 2.9 to 60???mol?L?1 of N-acetylcysteine, and a detection limit of 0.87???mol?L?1. The effect of other thiols on the system is also described. The relative standard deviation ranges between 0.6% and 3.5%. The method was applied to the determination of N-acetylcysteine in several pharmaceutical samples with recoveries that range from 97.7% to 101.1%. Figure
S1, S2: stopped-flow driving syringes 相似文献
2.
Aminopyrene was covalently anchored onto mesoporous silica through serial post-grafting to obtain a fluorescent solid that can be used as a sensing material for the determination of nitrite. The latter, in acidic medium, reacts with the secondary amino groups on the material to form a non-fluorescent nitroso derivative. Based on the fluorescence quenching caused by this specific reaction, a method was developed for the determination of nitrite at nanomolar levels. The range for detection of nitrite in 1.5?mol.L?1 HCl is linear between 1.50?nM to 0.45???M and 0.45???M to 2.22???M, the detection limit being 1.10?nM and 0.307???M respectively at an S/N of 3. Figure
Fluorescence quenching of aminopyrene-functionalized mesoporous silica when exposed to different concentrations of NO2 ? 相似文献
3.
Abbas Afkhami Tayyebeh Madrakian Reza Ahmadi Hasan Bagheri Masoumeh Tabatabaee 《Mikrochimica acta》2011,175(1-2):69-77
We have developed a solid phase extraction method for the determination of cadmium ions in aqueous samples. It is based on the adsorption of Cd(II) on alumina nanoparticles coated with sodium dodecyl sulfate and modified with a newly synthesized Schiff base. Analytical parameters such as pH value, amount of adsorbent, type and concentration of eluent, flow rates of the sample and eluent, sample volume and matrix effects were optimized. Desorption is accomplished with 2?mol?L?1 nitric acid. Cd(II) was then determined by flame atomic absorption spectrometry. The maximum enrichment factor is 75. Under the optimum experimental conditions, the detection limit is 0.14???g?L?1 in original solution. The adsorption capacity of the modified sorbent is 4.90?mg?g?1 for cadmium ions. The method was applied to the determination of trace quantities of Cd(II) in water, wastewater, and biological and food samples with satisfactory results. Figure
Schematic representation of the loading L on the alumina nanoparticles 相似文献
4.
Determination of acetamiprid by a colorimetric method based on the aggregation of gold nanoparticles
A method was developed for the detection of the insecticide acetamiprid based on the strong interaction of the cyano group of acetamiprid with gold nanoparticles (AuNPs). The interaction results in the aggregation of gold nanoparticles and is accompanied by a color change from red to purple. The concentration of acetamiprid can be determined qualitatively and quantitatively by visually monitoring the color change or by using a spectrometer. Transmittance electron microscopy and UV-vis spectroscopy have been used to characterize the process. The experimental parameters were optimized with regard to the size of the AuNPs, pH, and incubation time. Under optimal experimental conditions, linear relationships between the logarithm of the concentration of acetamiprid and the absorbance were found over the range of 0.66 to 6.6???M for AuNPs with diameters of 22.0?±?1.0?nm and of 6.6?C66???M for AuNPs with diameters of 15.0?±?1.0?nm. This method was successfully applied to detect acetamiprid in vegetables. Figure
A method was developed for the detection of acetamiprid based on the strong interaction of the cyano group of acetamiprid with gold nanoparticles. This method is rapid, sensitive and low-cost. It can be used for pesticide residues detection. 相似文献
5.
We have developed a sensor for the square wave anodic stripping voltammetric determination of Pb(II). A glassy carbon electrode was modified with a thin film of an antimony/poly(p-aminobenzene sulfonic acid) composite in air-saturated aqueous solution of pH 2.0. Compared to a conventional antimony film electrode, the new one yields a larger stripping signal for Pb(II). The conditions of polymerization, the concentration of Sb(III), the pH value of the sample solution, the deposition potential and time, frequency, potential amplitude, and step increment potential were optimized. Under the optimum conditions, a linear response was observed for Pb(II) in the range of 0.5 to 150.0 μg?L?1. The detection limit for Pb(II) is 0.1 μg?L?1. Figure
The surface of a glassy carbon electrode (GCE) was modified by electropolymerization of p-aminobenzene sulfonic acid (p-ABSA) and the modified electrode was then prepared by in situ depositing antimony and target metal on the poly(p-ABSA) coated glassy carbon electrode. The antimony/poly(p-ABSA) film electrode displays high electrochemical activity in giving a peak current that is proportional to the concentration of Pb(II) in a certain range. 相似文献
6.
A glassy carbon electrode modified with organic?Cinorganic pillared montmorillonite was used for voltammetric detection of mercury(II) in water. High sensitivity is obtained due to the use of the montmorillonites which displays outstanding capability in terms of adsorbing mercury ion due to its high specific surface and the presence of multiple binding sites. The experimental parameters and the effect of a chelating agent were optimized to further enhance sensitivity and selectivity. Linear calibration curves were obtained over the Hg(II) concentration range from 10 to 800???g?L?1 for 5?min accumulation, with a detection limit of 1???g?L?1. Simultaneous determination of Hg(II) and Cu(II) was also studied, and no interference was observed. Figure
Scheme for the Organic-inorganic pillared clay adsorbing mercury. 相似文献
7.
We report on a carbon paste electrode that was modified with a binuclear manganese(II) complex by the drop-coating method. A study on the mechanism of the electro-oxidation of tryptophan (Trp) at this electrode indicated that it enables Trp to be determined with good sensitivity and selectivity. Second-order derivative linear sweep voltammetry at pH 4.1 revealed that a sensitive anodic peak appears at 812?mV (vs. SCE) whose current is proportional to the concentration of Trp in the concentration range from 0.1 to 1.0???mol?L?1 and 1.0 to 80???mol?L?1, with a detection limit (S/N?=?3) of 0.08???mol?L?1 (60?s of accumulation). The method was applied to the determination of Trp in amino acid injection solutions with satisfactory results. Figure
The electrochemical behavior of tryptophan at a carbon paste electrode modified with a binuclear manganese(II) complex Mn2(phen)2(p-MBA)4(H2O) was investigated. The modified electrode showed high electrocatalytic activity toward the oxidation of tryptophan and the peak current increases linearly with tryptophan concentration in the range of 0.1 to 80???mol L?1. 相似文献
8.
Ping Tong Shurong Tang Yu He Yanhong Shao Lan Zhang Guonan Chen 《Mikrochimica acta》2011,173(3-4):299-305
The hepatotoxic microcystins, especially microcystin?CLR (MC?CLR), are causing serious problems to public health and fisheries. We describe here a label-free amperometric immunosensor for rapid determination of MC?CLR in water sample. The sensor was prepared by immobilizing antibody on a gold electrode coated with L-cysteine-modified gold nanoparticles. The stepwise self-assembly of the immunosensor was monitored and characterized by means of electrochemical impedance spectroscopy and differential pulse voltammetry. A 0.60?mmol L?1 solution of hydroquinone was used as the electron mediator. The immunosensor was incubated with MC?CLR at 25?°C for 20?min, upon which the differential pulse voltammetric current changed linearly over the concentration range from 0.05 to 15.00???g L?1, with a detection limit of 20?ng L?1. The developed biosensor was used to determine MC?CLR in spiked crude algae samples. The recovery was in the range from 95.6 to 105%. This method is simple, economical and efficient, this making it potentially suitable for field analysis of MC-LR in crude algae and water samples. Figure
The present investigation combines SAM monolayer with gold nanoparticles monolayer to prepare a stable film to immobilize the antibody, and takes hydroquinone as electron mediator, establishes a miniature, economic, compatible and label-free amperometric immunosensor for the quick detection of MC-LR. 相似文献
9.
Xiuhui He Zhaohong Su Qingji Xie Chao Chen Yingchun Fu Li Chen Ying Liu Ming Ma Le Deng Dilan Qin Yueping Luo Shouzhuo Yao 《Mikrochimica acta》2011,172(1-2):95-102
A simple, cheap, and nonpolluting method was developed for the cloud point extraction of gold (Au) and palladium (Pd). It is based on the complexation reaction of Au and Pd with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) and micelle mediated extraction of the complex using the non-ionic surfactant poly(ethylene glycol) mono-p-nonylphenyl ether (PONPE 7.5). Under the optimized experimental conditions, the enrichment factors are 16 and 17 for Au and Pd, respectively, for 15?mL of preconcentrated solution. The limits of detection are 3.8???g?L?1 and 1.8???g?L?1 for Au and Pd, respectively. The relative standard deviations are 1.4% for Au and 0.6% for Pd (n?=?11). The method was successfully applied to the determination of Au and Pd in certified reference materials and mine samples. Figure
CPE of gold(III) and palladium(II) 相似文献
10.
Ai-Jun Wang Pei-Pei Zhang Yong-Fang Li Jiu-Ju Feng Wen-Ju Dong Xue-Yan Liu 《Mikrochimica acta》2011,172(1-2):31-37
A solid bar microextraction (SBME) method containing sorbent materials 2?mg in the lumen of a porous hollow fiber membrane 2.5?cm for the extraction of carbamazepine, diclofenac and ibuprofen from river water samples is described. The desorbed analytes were analyzed using reversed-phase high performance liquid chromatography with ultraviolet detection. In order to achieve optimum performance, several extraction parameters were optimized. Of the sorbents evaluated, LiChrosorb RP-8 was the most promising. Under the optimized conditions, limits of detection from 0.7 to 0.9???g?L?1, precisions from 5.5 to 6.4% and a correlation coefficient of 0.999 were obtained for the target drugs over a concentration range of 1?C200???g?L?1. In comparison with the solid phase extraction, the SBME system offers distinct advantages due to its higher enrichment factors, lower consumption of organic solvents and time saving.
A solid bar microextraction method for the liquid chromatographic determination of trace diclofenac, ibuprofen and carbamazepine in river water 相似文献
11.
We report on a simple, sensitive and reliable method for the cloud point extraction of antimony (Sb) and its subsequent spectrophotometric detection. It is based on the color reaction of Sb (III) with iodide in acidic medium and subsequent micelle-mediated extraction of tetraiodoantimonate using a non-ionic surfactant in the absence of any chelating agent. The effects of reaction and extraction parameters were optimized. The calibration plot is linear in the range of 0.80–95?ng?mL?1 of antimony in the sample solution, with a regression coefficient (r) of 0.9994 (for n?=?9). The detection limit (at SNR?=?3) is 0.23?ng?mL?1, and the relative standard deviations at 10 and 70?ng?mL?1 of antimony are 3.32 and 1.85?% (at n?=?8), respectively. The method compared favorably to other methods and was applied to determine antimony in seawater, anti-leishmania drug (glucantime), and human serum. Figure
This method is based on the extraction of yellow iodoantimonous acid (HSbI4) into surfactant-rich phase of Triton X-114 when trivalent antimony in sulfuric acid solution is treated with an excess of potassium iodide solution. 相似文献
12.
We have modified gold nanoparticles (AuNPs) with triazole acetamide to obtain a material for the sensitive and selective colorimetric determination of iodide. The functionalized AuNPs were prepared by a reductive single chemical step using a Cu(I)-catalyzed click reaction. The presence of iodide ions induces the aggregation of these AuNPs and results in a color change from wine-red to purple. The iodide-induced aggregation can be detected visually with bare eyes, but also by photometry. The detection limit is as low as 15 nM. The method displays excellent selectivity for iodide over other anions due to the selective interaction with the amido groups of the triazole. The method was applied to the determination of iodide in spiked lake waters. Figure
New triazole acetamide functionalized gold nanoparticles (ATTP-AuNPs) for sensitive and selective colorimetric detection of I? were developed. ATTP-AuNPs showed excellent selectivity toward I? due to the interaction between the amide groups of ATTP and I?. 相似文献
13.
A new simple and sensitive method has been developed for the determination of trace levels of inorganic species in environmental water samples. It is based on the use of supramolecular?Cbased dispersive liquid?Cliquid microextraction (SM?CDLLME) prior to microsample introduction into FAAS. The ions are micro?Cextracted with coacervates composed of reverse micelles made from decanoic acid and dispersed in tetrahydrofuran?Cwater mixtures. Cobalt ion was used as a model ion, and 1?C (2?Cpyridylazo)?C2?Cnaphthol as the complexing agent. SM?CDLLME results from a combination of DLLME with coacervation?Cbased microextraction. It combines the advantages of DLLME with those of preconcentration based on coacervation and reverse micelles. Factors affecting the extraction efficiency of Co and its subsequent determination by FAAS were optimized. Under the optimized conditions and using 5.00?mL sample only, the enhancement factor is 58, the limit of detection is 4.2???g L?C1, and the relative standard deviations for 100???g L?C1 and 30???g L?C1 of Co are 2.1% and 3.8%, respectively (n?=?6). The accuracy of the method was confirmed by parallel analyses using the ASTM reference method.
Schematic representation SM?CDLLME enrichment method (Supramolecular assemblies were hired as extraction media in dispersive liquid?Cliquid microextraction. This method is based on microextraction of analytes with coacervates made up of decanoic acid reverse micelles dispersed in tetrahydrofuran (THF)?Cwater. Hazardous organic solvents as the microextraction solvent were avoided) 相似文献
14.
We have developed a method for the determination of mercury in water samples that combines dispersive liquid-liquid microextraction (DLLME) with back-extraction (BE) and detection by capillary zone electrophoresis. DLLME is found to be a simple, cost-effective and rapid method for extraction and preconcentration. The BE procedure is based on the fact that the stability constant of the hydrophilic chelate of Hg(II) with L-cysteine is much larger than that of the respective complex with 1-(2-pyridylazo)-2-naphthol. Factors affecting complex formation and extraction efficiency (such as pH value, concentration of the chelating agent, time of ultrasonication and extraction, and type and quantity of disperser solvent) were optimized. Under the optimal conditions, the enrichment factor is 625, and the limit of detection is 0.62???g?L?1. The calibration plot is linear in the range between 1 and 1,000???g?L?1 (R 2?=?0.9991), and the relative standard deviation (RSD, for n?=?6) is 4.1%. Recoveries were determined with tap water and seawater spiked at levels of 10 and 100???g?L?1, respectively, and ranged from 86.6% to 95.1%, with corresponding RSDs of 3.95?C5.90%. Figure
A method was developed based on the combination of dispersive liquid-liquid microextraction with back-extraction showing simplicity, cost-effectiveness, and rapidity for remarkably enhanced preconcentration, and detection by capillary zone electrophoresis occupying high resolving power, rapidity, low-cost, and environmental benignity, and applied for highly selective determination of trace mercury in water samples. 相似文献
15.
A differential pulse voltammetric method was developed for the simultaneous determination of paracetamol, 4-aminophenol and dopamine at pH 7.0 using a glassy carbon electrode (GCE) coated with gold nanoparticles (AuNPs) and a layered double hydroxide sodium modified with dodecyl sulfate (SDS-LDH). The modified electrode displays excellent redox activity towards paracetamol, and the redox current is increased (and the corresponding over-potential decreased) compared to those of the bare GCE, the AuNPs-modified GCE, and the SDS-LDH-modified GCE. The modified electrode enables the determination of paracetamol in the concentration range from 0.5 to 400???M, with a detection limit of 0.13???M (at an S/N of 3). The sensor was successfully applied to the stimultaneous determination of paracetamol and dopamine, and of paracetamol and 4-aminophenol, respectively, in pharmaceutical tablets and in spiked human serum samples. Figure
1. Gold nanoparticles and organophillic layered double hydroxide modified glassy carbon electrode was fabricated. 2. The modified electrode displayed excellent redox activity towards paracetamol. 3. This electrode was successfully applied to the simultaneous determination of paracetamol and dopamine, and of paracetamol and 4-aminophenol, respectively 相似文献
16.
We report on the construction of a label-free electrochemical immunosensor for detecting the core antigen of the hepatitis C virus (HCV core antigen). A glassy carbon electrode (GCE) was modified with a nanocomposite made from gold nanoparticles, zirconia nanoparticles and chitosan, and prepared by in situ reduction. The zirconia nanoparticles were first dispersed in chitosan solution, and then AuNPs were prepared in situ on the ZrO2-chitosan composite. In parallel, a nanocomposite was synthesized from AuNPs, silica nanoparticles and chitosan, and conjugated to a secondary antibody. The properties of the resulting nanocomposites were investigated by UV-visible photometry and transmission electron microscopy, and the stepwise assembly process was characterized by means of cyclic voltammetry and electrochemical impedance spectroscopy. An sandwich type of immunosensor was developed which displays high sensitivity to the HCV core antigen in the concentration range between 2 and 512?ng?mL?1, with a detection limit of 0.17?ng?mL?1 (at S/N?=?3). This immunosensor provides an alternative approach towards the diagnosis of HCV. Fig
A sandwich-type immunosensor was constructed for the detection of HCV core Ag. AuNPs/ZrO2-Chits nanocomposites were prepared by in situ reduction method. AuNPs/SiO2-Chits nanocomposite integrated with secondary antibody (Ab2) without labeled HRP. The immunosensor displayed high sensitivity to HCV core antigen with a detection limit of 0.17?ng?mL?1 (S/N?=?3). 相似文献
17.
We report on the electrochemical formation of copper oxide nanoparticles (CuO-NPs) at a carbon ceramic electrode (CCE) as a highly-porous substrate. A copper film was deposited on the surface of the CCE and derivatized in situ to give CuO-NPs by potential cycling between ?0.8 and 0.35?V in strongly alkaline solution. The electrode was characterized by scanning electron microscopy and cyclic voltammetry. The CuO-NPs exhibited excellent electrocatalytic activity toward the oxidation of L-tyrosine (L-Tyr) in responding linearly in the 2 to 1,350???M concentration range, an associated detection limit (S/N?=?3) of 160?nM, and a sensitivity of 0.61?A?M?1?cm?2.
Cyclic voltammograms of the bare CCE (a, c) and nano-copper oxide coated CCE (b, d) in 0.05?mol L?1 NaOH solution in the absence (a, b) and presence of 6?mmol L?1 L-Tyr (c, d) at scan rate of 50?mV?s?1 相似文献
18.
Abbas Afkhami Mohammad Saber-Tehrani Hasan Bagheri Tayyebeh Madrakian 《Mikrochimica acta》2011,172(1-2):125-136
A new solid-phase extraction sorbent was used for the preconcentration of Pb(II) and Cr(III) ions prior to their determination by flame atomic absorption spectrometry. It was prepared by immobilization of 2,4-dinitrophenylhydrazine on nano-alumina coated with sodium dodecyl sulfate. The sorbent was characterized by scanning electron microscopy, N2 adsorption and Fourier transform infrared spectrometry, and used for preconcentration and separation of Pb(II) and Cr(III) from aqueous solutions. The ions on the sorbent were eluted with a mixture of nitric acid and methanol. The effects of sample pH, flow rates of samples and eluent, type of eluent, breakthrough volume and potentially interfering ions were studied. Linearity is maintained between 1.2 and 350???g?L-1 of Pb(II), and between 2.4 and 520???g?L-1 of Cr(III) for an 800-mL sample. The detection limit (3?s, N?=?10) for Pb(II) and Cr(III) ions is 0.43 and 0.55???g?L-1, respectively, and the maximum preconcentration factor is 267. The method was successfully applied to the evaluation of these trace and toxic metals in various water, food, industrial effluent and urine samples. Figure
Recovery percentage of Pb(II) and Cr(III) ions at different solution volumes. 相似文献
19.
We describe a simple and rapid method for the ultrasound-assisted microextraction of antimony using the solidified floating organic drop method. The effects of pH, type and volume of the extractant, time of sonication, amount of chelating agent, type and amount of surfactant were investigated and optimized. Bromopyrogollol red is acting as the chelating agent. Antimony(III) ion was extracted into finely dispersed droplets of undecanol after ion-pair formation with the water soluble chelator and the cationic detergent benzyldimethyltetradecylammonium chloride. Flame atomic absorption spectrometry was used for the detection. The resulting calibration is linear in the concentration range from 4.0 to 900?ng?mL-1 of Sb(III) with a correlation coefficient of 0.9981. The enrichment factor is 67, the detection limit is 0.62?ng?mL-1, and the relative standard deviation is?±?3.6% (at 100?ng?mL-1; for n?=?10). The method was successfully applied to the determination of antimony in water samples. Figure
Antimony and many of its compounds are toxic and can damage the kidneys and the liver, causing death in a few days. Concentration of this element is very low in nature and hence their determination required sensitive analytical techniques. One such technique is an ultrasound assisted emulsification microextraction procedure. 相似文献
20.
A carbon paste electrode (CPE) was modified with multi-wall carbon nanotubes and successfully applied to the determination of silver ion by differential pulse anodic stripping voltammetry. Compared to a conventional CPE, a remarkably improved peak current response and sensitivity is observed. The analytical procedure consisted of an open circuit accumulation step for 2?min in ?0.4?V, this followed by an anodic potential scan between +0.2 and?+?0.6?V to obtain the voltammetric peak. The oxidation peak current is proportional to the concentration of silver ion in the range from 1.0?×?10?8 to 1.0?×?10?5?mol?L?1, with a detection limit of 1.8?×?10?9?mol?L?1 after an accumulation time of 120?s. The relative standard deviation for 7 successive determinations of Ag(I) at 0.1???M concentration is 1.99%. The procedure was validated by determining Ag(I) in natural waters. Figure
Differential pulse voltammogram (DPV) of Ag+ solution at MCPE 相似文献