Concentration Of Chelating Agent Research Articles

Automated Single-Phase Liquid-Liquid Extraction for Determination of Cr(VI) Using Graphite Furnace Atomic Absorption Spectrophotometry without Wet Digestion of Samples

This paper proposes a method to perform rapid and sensitive graphite furnace atomic absorption spectrometry (GFAAS) determination of Cr(VI) in vinegar samples without wet digestion. Taking into account low levels of Cr(VI) and the presence of several concomitants in the sample matrix, the proposed method uses single-phase liquid-liquid extraction (SPLLE). The method is automated, employing a flow-batch analyzer (FBA) which uses a mixing chamber designed to emulate a separation funnel promoting the formation/break of the single-phase solution, reaction and extraction. The Cr(VI) extraction procedure was performed by proportioned mixing of the vinegar sample (aqueous phase), amyl alcohol (organic phase), and ethanol (consolute) to form a single-phase solution. The chelating reagent sodium diethyldithiocarbamate (DDTC) dissolved in the consolute reacts rapidly with Cr(VI), in the single phase to produce a stable Cr-DDTC complex. The single-phase break step is performed by adding an excess of Britton-Robinson buffer, and then the organic phase enriched with Cr(VI) was analyzed by GFAAS. Factors such as extraction steps, single-phase composition, pH, chelating agent concentration, and flow-batch parameters were optimized. The FBA-SPLLE-GFAAS was evaluated in vinegar samples showing satisfactory analytical features in terms of limit of quantification (0.86 μg L −1 ), precision (RSD <12 %), characteristic mass (m0 = 0.32 pg), high sampling rate (26 h −1 ), and accuracy (recovery rate = 82–108 %). The proposed method requires one-step extraction and is eco-friendly since it consumes low amounts of non-toxic chemicals and generates little waste (about 700 μL per determination).

Selective and sensitive speciation analysis of Cr(VI) and Cr(III), at sub-μg L−1 levels in water samples by electrothermal atomic absorption spectrometry after electromembrane extraction

In this work, electromembrane extraction in combination with electrothermal atomic absorption spectrometry (ET-AAS) was investigated for speciation, preconcentration and quantification of Cr(VI) and Cr(III) in water samples through the selective complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) as a complexing agent. DPC reduces Cr(VI) to Cr(III) ions and then Cr(III) species are extracted based on electrokinetic migration of their cationic complex (Cr(III)-DPC) toward the negative electrode placed in the hollow fiber. Also, once oxidized to Cr(VI), Cr(III) ions in initial sample were determined by this procedure. The influence of extraction parameters such as pH, type of organic solvent, chelating agent concentration, stirring rate, extraction time and applied voltage were evaluated following a one-at-a-time optimization approach. Under optimized conditions, the extracted analyte was quantified by ETAAS, with an acceptable linearity in the range of 0.05–5ngmL−1 (R2 value=0.996), and a repeatability (%RSD) between 3.7% and 12.2% (n=4) for 5.0 and 1.0ngmL−1 of Cr(VI), respectively. Also, we obtained an enrichment factor of 110 that corresponded to the recovery of 66%. The detection limit (S/N ratio of 3:1) was 0.02ngmL−1. Finally, this new method was successfully employed to determine Cr(III) and Cr(VI) species in real water samples.

Engineering the solid oxide fuel cell electrocatalyst infiltration technique for industrial use

In this work, we explore various parameters for infiltrating La0.6Sr0.4CoO3-δ (LSCo) into the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) – Ce0.8Sm0.2O2 (SDC) cathode of a planar solid oxide fuel cell (SOFC) using an automated solution dispensing technique for commercial deployment of infiltrated SOFCs by industry. Substrate temperature, chelating agent concentration, and surfactant type were explored to develop a 1-step infiltration process for delivering 8–10 weight percent of LSCo electrocatalyst to the cathode active layer. The results confirm increased fuel cell performance and durability by optimizing the infiltrate solution for increased transport into the cathode's microstructure.

Ultrasound enhanced air-assisted surfactant liquid–liquid microextraction based on the solidification of an organic droplet for the determination of chromium in water, air and biological samples

Ultrasound enhanced air-assisted surfactant liquid–liquid microextraction based on the solidification of a floating organic droplet (UEAASLLM-SFO) followed by the electrothermal atomic absorption spectrometry was evaluated for extraction and preconcentration of chromium species in water, air and biological samples. Sodium dodecyl sulfate (SDS) was used as an ion-pairing age. The Cr(VI) was complexed with 1,5 diphenylcarbazide (DPC) and extracted into 1-undecanol. Fine extraction solvent drops were rapidly formed by pulling in and pushing out the mixture of sample solution and extraction solvent for 5 times repeatedly using a 10-mL glass syringe. Ultrasound irradiations enhanced the rapid formation of fine droplets of the solvent in the sample solution and promoted the mass transfer of analyte into the extractant. Cr(III) ion was determined after oxidation to Cr(VI) using KMnO4 in acidic media. The effects of various parameters on the extraction process such as type and volume of extraction solvent, acidity, chelating agent concentration, concentration of surfactant, sonication time and number of extraction times were investigated. Under the optimized conditions, the limit of detection and the limit of the quantification were found 0.003 and 0.01μgL−1 with preconcentration factor of 174 for Cr(VI) respectively. The relative standard deviation (RSD, n=5) of 0.1μgL−1 Cr(VI) was 3.65%. The analytical curve for Cr(VI) was linear in the range of 0.01–0.3μgL−1. The accuracy of the method was performed by an analysis of a certified reference material (CRM), the reference standard SRM1640-Natural water (NIST). The method was successfully applied to the speciation and determination of Cr(III) and Cr(VI) in water, air and biological samples.

Lithium iron silicate sol–gel synthesis and electrochemical investigation

Li2FeSiO4 was synthesized through Sol–Gel method and the effect of calcination temperature, time and chelating agent concentration were investigated. Appropriate calcination temperature above 550 °C was determined by TG/DTA analysis. Afterward, the dried gel powder was calcined at each temperature of 650 °C, 700 °C and 750 °C for 1, 2 and 3 h. XRD studies illustrated the most appropriate calcination temperature of 700 °C for 1 h. To compare the effect of chelating agent concentration, citric acid with molar ratio of 1/3, 2/3 and 1 were used which 1/3 was determined as the best concentration. FE-SEM observation showed that mean grain is size lower than 100 nm. By using this material, a three electrodes test cell was assembled and its electrochemical properties were investigated. The results showed high charge capacity which could be achieved at current density of 0.05C.

Application of Response Surface Methodology and Central Composite Design for the Optimization of Metformin Microsphere Formulation using Tangerine (Citrus tangerina) Pectin as Copolymer

Aims: To prepare metformin microspheres by ionic gelation using novel pectin from the peel of tangerine, Citrus tangerina (Rutaceae), as a copolymer with sodium alginate. Study Design: Central composite design and response surface methodology. Place and Duration of Study: Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria, between September 2015 and February 2016. Methodology: Central composite design and response surface methodology were applied to evaluate the interactive effects of three variables: Percent of pectin in polymer blend, X1, (50 to 75% w/w), curing time, X2, (10 to 30 min) and concentration of chelating agent (calcium chloride), X3, (5 to 10% w/v) on entrapment and dissolution time (t90). Results: Entrapment efficiency was 59.10 to 94.90% and t90 was 6.52 to 10.50 h. X1 and X3 had significant effects on entrapment and t90 (p < 0.0001). The interactions between X2 and X3 was significant at p = 0.033 for entrapment. The correlation coefficients (R2 = 0.9557 and R2(Adj) = 0.9158 for entrapment; R2 = 0.9677 and R2 (Adj) = 0.9387 for t90) showed that the regression model represented the experimental data well. The optimization of the analyzed responses demonstrated that peak conditions for obtaining desired maximum responses, entrapment (102.66%) and t90 (12.27 h), were 82.91% w/w pectin; 36.33 min curing time and 7.50% w/w of calcium chloride. Conclusion: Tangerine pectin could serve as a cheaper alternative polymer for the formulation of microspheres.

Decanoic Acid Reverse Micelle-Based Coacervates for Microextraction of Silver in Natural Waters Prior to Flame Atomic Absorption Spectrometry Determination

In the present work, a novel, simple, and efficient method for the determination of silver in natural water samples was developed. The method is based on the extraction of silver with coacervate made up of decanoic acid reverse micelles and the subsequent determination by flame atomic absorption spectrometry (FAAS). Dithizone was used as a chelating agent. To obtain the best extraction results, some experimental parameters (such as coacervate composition, pH, concentration of chelating agent, and ionic strength) affecting the extraction efficiency were investigated and optimized. Under optimum conditions, the calibration curve was linear in the concentration range of 5-200 µg L-1, with the correlation coefficient (r) equal to 0.995. The limit of detection and the enrichment factor were 1.6 µg L-1 and 15, respectively. The method was successfully applied to the analysis of silver in natural water samples.

Synthesis and Electrochemical Performance of Nickel-Rich Layered-Structure LiNi0.65Co0.08Mn0.27O2 Cathode Materials Comprising Particles with Ni and Mn Full Concentration Gradients

In this work, nickel-rich, layered-structure LiNi0.65Co0.08Mn0.27O2 cathode materials were synthesized and compared with materials of the same overall composition, but with a concentration gradient throughout the particles: the Ni concentration is higher at the center of the particles and lower at surface, while the opposite is true for the Mn concentration. The co-precipitation synthesis parameters were optimized, with two different annealing protocols for the final products and the effect of chelating agent concentration during synthesis examined. The gradient materials provided superior capacity and rate capability than their respective non-gradient materials, at normal operating potentials and temperatures, e.g. 30°C up to 4.3 V vs. Li. The reasons for the improved discharge capacity of the gradient materials were explored through impedance spectroscopy and post-mortem characterization. The gradient structure evolution was examined via TEM and electron diffraction measurements of particle cross-sections. Prolonged cycling, even at elevated temperatures, did not change the initial concentration profiles determined by the synthesis. Additionally, long-term cycling experiments of the second-generation material electrodes vs. graphite electrodes in full cells were performed in order to explore the practical advantage of these novel materials.

Determination of Lead in Water Samples Using a New Vortex-Assisted, Surfactant-Enhanced Emulsification Liquid-Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry.

A low toxic solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (LT-VSLLME) combined with graphite furnace atomic absorption spectrometry was developed for the extraction and determination of lead (Pb) in water samples. In the LT-VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which acted as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The influences of analytical parameters, including extraction solvent type and its volume, surfactant type and its volume, pH, concentration of chelating agent, salt effect and extraction time were investigated. Under the optimized conditions, a good relative standard deviation of 3.69% at 10 ng L(-1) was obtained. The calibration graph showed a linear pattern in the ranges of 5-30 ngL(-1), with a limit of detection of 0.76 ng L(-1). The linearity was obtained by five points in the concentration range of 5-30 ngL(-1). The enrichment factor was 320. The procedure was applied to wastewater and river water, and the accuracy was assessed through the analysis of the recovery experiments.

A novel cleaner for colloidal silica abrasive removal in post-Cu CMP cleaning**Project supported by the Specific Project Items No. 2 in National Long-Term Technology Development Plan (No. 2009zx02308-003) and the Hebei Province Department of Education Fund (No. QN2014208).

A novel cleaning solution, named FA/O alkaline cleaner, was proposed and demonstrated in the removal of colloidal silica abrasives. In order to remove both the chemical and physical absorbed colloidal silica abrasives, an FA/OII chelating agent and non-ionic surfactant were added into the cleaner. By varying the concentration of chelating agent and non-ionic surfactant, a series of experiments were performed to determine the best cleaning results. This paper discusses the mechanism of the removal of colloidal silica abrasives with a FA/O alkaline cleaner. Based on the experiment results, it is concluded that both the FA/OII chelating and non-ionic surfactant could benefit the removal of colloidal silica abrasives. When the concentration of FA/OII chelating agent and FA/O non-ionic surfactant reached the optima value, it was demonstrated that silica abrasives could be removed efficiently by this novel cleaning solution.

Cloud point-TiO2/sepiolite composites extraction for simultaneous preconcentration and determination of nickel in green tea and coconut water

In this work, cloud point-TiO2/sepiolite composites–octyl alcohol extraction combined with UV–vis spectrometry was applied to analyze nickel in real samples. Trace nickel was separated and preconcentrated with PAN as chelating agent, and TiO2/sepiolite composites—octylphenoxypolyethoxyethanol (TX-114)—octyl alcohol as extraction agent. Factors influencing extraction efficiency, such as concentrations of TX-114 and octanol, type of the desorption on the extraction system, concentration of chelating agent, pH, incubation temperature, incubation time and conditions of phase separation were investigated and optimized systematically. The results showed that TiO2/sepiolite composites exert significant effects on the extraction efficiency; especially nickel concentration is very low. Under the optimal conditions, the absorbance signal is linear with nickel concentration in the range of 0.02–3 mg L−1 and the detection limit was 5 μg L−1. The developed method was successfully applied to the determination of nickel in natural products of Baisha green tea and coconut water in Hainan.

In situ emulsification microextraction using a dicationic ionic liquid followed by magnetic assisted physisorption for determination of lead prior to micro-sampling flame atomic absorption spectrometry

For the first time, a simple and efficient in situ emulsification microextraction method using a dicationic ionic liquid followed by magnetic assisted physisorption was presented to determine trace amounts of lead. In this method, 400 μL of 1.0 mol L−1 lithium bis (trifluoromethylsulfonyl) imide aqueous solution, Li[NTf2], was added into the sample solution containing 100 μL of 1.0 mol L−1 1,3-(propyl-1,3-diyl) bis (3-methylimidazolium) chloride, [pbmim]Cl2, to form a water immiscible ionic liquid, [pbmim][NTf2]2. This new in situ formed dicationic ionic liquid was applied as the acceptor phase to extract the lead-ammonium pyrrolidinedithiocarbamate (Pb-APDC) complexes from the sample solution. Subsequently, 30 mg of Fe3O4 magnetic nanoparticles (MNPs) were added into the sample solution to collect the fine droplets of [pbmim][NTf2]2, physisorptively. Finally, MNPs were eluted by acetonitrile, separated by an external magnetic field and the obtained eluent was subjected to micro-sampling flame atomic absorption spectrometry (FAAS) for further analysis. Comparing with other microextraction methods, no special devices and centrifugation step are required. Parameters influencing the extraction efficiency such as extraction time, pH, concentration of chelating agent, amount of MNPs and coexisting interferences were studied. Under the optimized conditions, this method showed high extraction recovery of 93% with low LOD of 0.7 μg L−1. Good linearity was obtained in the range of 2.5–150 μg L−1 with determination coefficient (r2) of 0.9921. Relative standard deviation (RSD%) for seven repeated measurements at the concentration of 10 μg L−1 was 4.1%. Finally, this method was successfully applied for determination of lead in some water and plant samples.

A Speciation Study on the Perturbing Effects of Iron Chelators on the Homeostasis of Essential Metal Ions.

A number of reports have appeared in literature calling attention to the depletion of essential metal ions during chelation therapy on β-thalassaemia patients. We present a speciation study to determine how the iron chelators used in therapy interfere with the homeostatic equilibria of essential metal ions. This work includes a thorough analysis of the pharmacokinetic properties of the chelating agents currently in clinical use, of the amounts of iron, copper and zinc available in plasma for chelation, and of all the implied complex formation constants. The results of the study show that a significant amount of essential metal ions is complexed whenever the chelating agent concentration exceeds the amount necessary to coordinate all disposable iron —a frequently occurring situation during chelation therapy. On the contrary, copper and zinc do not interfere with iron chelation, except for a possible influence of copper on iron speciation during deferiprone treatment.

Insight on the Feasibility of Producing Durable Paper from Spruce Pulp using the Sulfate Process

Bleached spruce sulfate pulp was used in this study to produce paper handsheets. Ethylene diamine tetra acetic acid (EDTA( was introduced as a chelating agent in concentrations of 0, 0.25, 0.5, and 0.75%. The handsheets were exposed to UV light at wavelengths ranging from 330 to 440 nm, with time intervals of 0, 10, 20, 30, 40, and 50 h. Finally, the strength properties were measured based on ISO standards. The strength indices of the handsheets were improved by adding the proper concentration of EDTA chelating agent, in comparison with the control sample. Furthermore, increasing the aging time reduced the breaking length, tear strength, folding endurance, burst strength, and tensile strength. Tear index, tensile strength, tearing strength, bursting strength, and folding endurance were decreased respectively by 41.9, 3.1, 28.2, 29.7, and 8.6 percent without EDTA treatment by increasing the aging time.

Chelating-Agent Enhanced Oil Recovery for Sandstone and Carbonate Reservoirs

Summary Recently low-salinity waterflooding was introduced as an effective enhanced-oil-recovery (EOR) method in sandstone and carbonate reservoirs. The recovery mechanisms that use low-salinity-water injection are still debatable. The suggested possible mechanisms are: wettability alteration, interfacial-tension (IFT) reduction, multi-ion exchange, and rock dissolution. In this paper, we introduce a new chemical EOR method for sandstone and carbonate reservoirs that will give better recovery than the low-salinity-water injection without treating or diluting seawater. In this study, we introduce a new chemical EOR method that uses chelating agents such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA) at high pH values. This is the first time for use of chelating agents as standalone EOR fluids. Coreflood experiments, interfacial and surface tensions, and zeta-potential measurements are performed with DTPA, EDTA, and HEDTA chelating agents. The chelating-agent concentrations used in the study were prepared by diluting the initial concentration of 40 wt% with seawater and injecting it into Berea-sandstone and Indiana-limestone cores of a 6-in. length and a 1.5-in. diameter saturated with crude oil. The coreflooding experiments were performed at 100°C and a 1,000-psi backpressure. Low-salinity-water and seawater injections caused damage to the reservoir because of the calcium sulfate scale deposition during the flooding process. The newly introduced EOR method did not cause calcium sulfate precipitation, and the core permeability was not affected. The core permeability was measured after the flooding process, and the final permeability was higher than the initial permeability in the case of chelating-agent injection. The coreflooding effluent was analyzed for cations with the inductively coupled plasma (ICP) spectroscopy to explain the dissolution-recovery mechanism. The effect of iron minerals on the rock-surface charge was investigated through the measurements of zeta potential for different rocks containing different iron minerals. HEDTA and EDTA chelating agents at 5 wt% concentration prepared in seawater were able to recover more than 20% oil from the initial oil in place from sandstone and carbonate cores. ICP measurements supported the rock-dissolution mechanism because the calcium, magnesium, and iron concentrations in the effluent samples were more than those in the injected fluids. The IFT-reduction mechanism was confirmed by the low IFT values obtained in the case of chelating agents. The type and concentration of chelating agents affected the IFT value. Higher concentrations yielded lower IFT values because of the increase in carboxylic-group concentration. We found that the high-pH chelating agents increased the negative value of zeta potential, which will change the rock toward more water-wet.

CLOUD POINT EXTRACTION FOR PRE-CONCENTRATION AND DETERMINATION OF PALLADIUM IN WATER AND FOOD SAMPLES BY VISUAL AND FLAME ATOMIC ABSORPTION SPECTROMETRYY

The cloud point extraction (CPE) method was successfully employed for the separation and pre-concentration of trace amounts of palladium prior to its determination either by flame atomic absorption spectrometry (FAAS) or using visual spectrophotometry. Palladium(II) reacts with 2-Hydroxyimino-3-(2-hydrazonopyridyl)-butane (HHB) as chelating agent in the presence of p -octylpolyethyleneglycolphenylether (Triton X-100) as a nonionic surfactant giving a purple to pink surfactant rich phase chelate which could be used for CPE. The effects of experimental conditions such as pH, chelating agent and surfactant concentrations, equilibration temperature and time on CPE were studied. The performance characteristics of the method such as linearity, detection limit, pre-concentration and improvement factors were evaluated. Linearity was obeyed in the range of 0.5−15 and 0.4-18.0 ng mL −1 of Pd (II) with a detection limit of 0.08 and 0.035 ng mL −1 using FAAS and visual spectrometry, respectively. Validation of the method revealed good performance characteristics including good selectivity for Pd 2+ over a wide variety of other diverse cations and anions, high reproducibility, low detection limit, acceptable accuracy and precision. The proposed method was successfully applied for the assessment of palladium (II) traces in water and food samples with satisfactory results.

Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40μL of 1,2-dichlorobenzene (extraction solvent) and 900μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4μgL−1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178μgL−1 and from 1.38 to 3.74mgL−1, respectively.

Determination of Gold in Various Environment Samples by Flame Atomic Absorption Spectrometry Using Dispersive Liquid–Liquid Microextraction Sampling

A new dispersive liquid-liquid microextraction separation/preconcentration procedure as a rapid sample-preparation technique is proposed for detection of ultra trace amounts of Au(III) in various media by flame atomic absorption spectrometry using 1,5-diphenyl-1,3,5-pentanetrione as chelating agent. Carbon tetrachloride and methanol were used as extraction and dispersive solvents, respectively. Various parameters that affect the extraction efficiency such as pH, centrifugation rate and time, chelating agent concentration and sampling volume on the recovery of Au(III) were investigated. Under optimum conditions, the enhancement factor of 750, relative standard deviation of 2.7 % and calibration graphs obtained in the concentration range of 0.04-5.6 μg L −1 for gold were obtained. The limit of detection was 1.1 ng L −1 . The accuracy of the method was performed by analysis of the certified reference material (CDN-PGMS-10). The developed method was applied successfully to the determination of gold in the catalytic converter, anode slime, ore and seawater samples. The results show that dispersive liquid-liquid microextraction procedure is sensitive, rapid, simple and safe for the separation/preconcentration of gold from complex sample media.

Next generation barrier CMP slurry with novel weakly alkaline chelating agent

To strengthen the device performance with the pattern wafer by enhancing the Cu polishing rate and improve the surface roughness with the Cu lines, a new weakly alkaline chelating agent with a barrier slurry is developed to meet the process demand of the advanced barrier chemical mechanical planarization (CMP). This new chelating agent has a stronger chelating ability and a lower pH value than the previous generation-FA/O I chelating agent researched before. Without an unstable oxidant agent added in the polishing slurry, it is difficult to enhance the copper polishing rate during the barrier CMP. The stronger chelating ability of the new chelating agent could increase the copper polishing rate along with controlling the Cu/Ta/TEOS removal rate selectivity to meet the requirements of the IC fabrication process. Thus it has solved the problem of excessive roughness due to the lower polishing rate, avoiding reducing the device performance with the pattern wafer. The new chelating agent with its lower pH value could make it possible to protect the low-k dielectric under the barrier layer from structurally breaking. The CMP experiment was performed on the 12 inch MIT 854 pattern wafers with the barrier slurry containing the new weakly alkaline chelating agent. By the DOE optimization, the results indicate that as the new chelating agent concentration in the slurry was up to 2.5 mL/L, the copper polishing rate is about 31.082 nm/min. Meanwhile, the wafer surface has a rather low roughness value of 0.693 nm (10 × 10 μm), the correction ability with the above slurry is adapted to the next generation barrier CMP and the k value of the low-k dielectric seems to have no k-shift. All the results presented show that the new weakly alkaline chelating agent with its superior performance can be used for the advanced barrier CMP.

Dispersive liquid–liquid microextraction based on the solidification of floating organic drop followed by ICP-MS for the simultaneous determination of heavy metals in wastewaters

In the present work, a dispersive liquid–liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Pb, Co, Cu, Ni, Zn. The influences of analytical parameters, including pH, extraction solvent volume, disperser solvent volume, concentration of chelating agent on the quantitative recoveries of Pb, Co, Cu, Ni, Zn were investigated. The effect of the interfering ions on the analytes recovery was also investigated. Under the optimized conditions, the limits of detection were 0.97–2.18ngL−1. The relative standard deviations (RSDs) were 2.62–4.51% (n=7, C=20ngL−1). The proposed method was successfully applied for the analysis of ultra trace metals in wastewater samples.