Interference Of Cations Research Articles

Label-free gold nanoparticles for the determination of neomycin

A new spectrophotometric method for the determination of neomycin has been developed. The method is based on aggregation of label-free gold nanoparticles leading to change in absorption spectra and color of the solution. Influence of different factors (the concentration of ethylenediaminetetraacetate (EDTA), pH, the concentrations of neomycin and the nanoparticles) on the aggregation and analytical performance of the method was investigated. EDTA plays an important role not only as a masking agent to eliminate interferences of metal cations but strongly affects the sensitivity of the nanoparticles relative to neomycin. The method allows to determine neomycin with detection limit of 28ngmL−1. It was applied to analysis of eye- and ear-drops. The sample pretreatment is simply done by diluting the formulation with water.

Flow-Injection Spectrophotometric Determination of Bromate in Bottled Drinking Water Samples Using Chlorpromazine Reagent and a Liquid Waveguide Capillary Cell

In this work, aiming to develop a simple, inexpensive method for the determination of low bromate levels in water samples, a liquid waveguide capillary cell (LWCC) was coupled to a FIA system. The long optical path (100 cm) of the LWCC was used to improve the sensitivity and the limit of detection without resorting to any off-line or in-line preconcentration processes. The spectrophotometric determination was based on the oxidation of chlorpromazine by bromate in an acidic medium, resulting in the formation of a colored radical product. Sulfamic acid was added to the reagent for minimizing the interference of nitrite, and a chelating ion exchange resin was used to remove major cationic interferences. The developed system allowed the determination of bromate within the range between 1 - 20 μg L(-1) with a detection limit of 0.2 μg L(-1).

Improvement on the modified Lowry method against interference of divalent cations in soluble protein measurement

This paper systematically investigated the interference of calcium and magnesium in protein measurement with a modified Lowry method first proposed by Frølund et al. (Appl Microbiol Biotechnol 43:755-761, 1995). This interference has in the past been largely ignored resulting in variable and unreliable results when applied to natural water matrices. We discovered significant formation of calcium and magnesium precipitates that lead to a decline in light absorbance at 750 nm during protein determination. Underestimation of protein concentration (sometimes even yielding negative concentrations) and low experiment reproducibility were demonstrated at high concentrations of divalent cations (e.g., [Ca(2+)] over 1 mmol L(-1)). To eliminate interference from calcium and magnesium, two pretreatment strategies were established based on cation exchange and dialysis. These pretreatments were convenient and were found to be highly effective in removing calcium and magnesium in protein samples. By using the modified Lowry method with these pretreatments, proteins in standard solutions and in wastewater samples were successfully quantified with good reliability and reproducibility. In addition, we demonstrated that simultaneous quantification of humic substances with the modified Lowry method was not affected by the two pretreatments. These approaches are expected to be applicable to protein and humic substance determination in different research fields, in cases where the modified Lowry method is sensitive to divalent cation concentrations.

Imprinted polymer-based extraction for speciation analysis of inorganic tin in food and water samples

In this study, an ion imprinted polymer (IIP), tin (IV)–4-(2-pyridylazo) resorcinol (PAR) complex (Sn(IV)–PAR–IIP) has been synthesized for speciation and selective solid-phase extraction (SPE) of tin species from food and water samples. For this purpose, copolymerization of Sn(IV)–4-(2-pyridylazo) resorcinol (PAR) complex was performed using methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), and 2,2′-Azobisisobutyronitrile (AIBN) as functional monomer, cross-linking agent, and initiator, respectively. The polymer particles were characterized by FT-IR, and thermogravimetric (TG) analyses. The effects of different variables such as solution pH, mass of the polymer, extraction and elution time, and type and volume of the eluent for elution of tin were evaluated by Box–Behnken design and response surface methodology. The significance of independent variables and their interactions were tested by the analysis of variance (ANOVA) with 95% confidence limits. The optimal conditions at extraction step were 8, 70mg, and 25min for solution pH, amount of polymer, and extraction time, respectively. Also, the optimal values for the elution step were 6.5mL of HCl (4M) as the eluent volume and type and elution time of 120min. The detection limit of the proposed method was found to be 1.3μgL−1 and a linear dynamic range (LDR) in the range of 5–200μgL−1 was obtained. The influence of various cationic interferences on recovery percentage of Sn(IV) was studied. The method was applied to recovery and determination of tin species in different real samples.

Spectrophotometric Complexation Studies of Some Transition and Heavy Metals with a New Pyridine Derivative Ligand and Application of It for Solid Phase Extraction of Ultratrace Copper and Determination by Flame Atomic Absorption Spectrometry

A new pyridine derivative ligand, (E)-(Pyridine-2-ylmethylidene) ({2-(E)-(Pyridine-2-ylmethylidene) amino] ethyl} has been synthesized and kf value of it’s complexes with Cu2+, Ni2+, Cd2+, Zn2+, Co2+, Hg2+ and Ag+ has been determined spectrophometrically. The stability of the complexes to vary in acetonitrile solvent was in the order of Cu2+ > Ni2+ > Cd2+ > Zn2+ > Co2+ > Hg2+ > Ag+, thus because this ligand have good selectivity to copper ion, a simple, reliable and rapid method for preconcentration and determination of the ultratrace amount of copper using octadecyl silica membrane disk modified by this ligand, and determination by flame atomic absorption has been presented. Various parameters including pH of aqueous solution, flow rates, the amount of ligand and the type of stripping reagent were optimized. Under optimum experimental conditions, the breakthrough volume is greater than 2000 ml with an enrichment factor of more than 400 and 0.054 μg×L?1 detection limit. The capacity of the membrane disks modified by 6 mg of the ligand has been found to be330.17 gof copper. The effects of various cationic interferences on the percent recovery of copper ion were studied. The method has been successfully applied for the determination of copper ion in different water samples.

Atomic absorption spectrometric determination of Al3+ and Cr3+ after preconcentration and separation on 3-mercaptopropionic acid modified silica coated-Fe3O4 nanoparticles

A new magnetic solid sorbent was synthesized using 3-mercaptopropionic acid grafted silica modified Fe3O4 magnetic nanoparticles. The sorbent was characterized by SEM, XRD, and FT-IR and used for solid phase extraction of Al3+ and Cr3+ ions. Al3+ and Cr3+ ions were measured by graphite furnace and flame atomic absorption spectrometry, respectively. The optimal extraction/preconcentration conditions including pH of sample solution, desorption conditions (type, concentration, and volume of the eluent), sonication time, sample volume, adsorbent amount, and interfering ions were studied. Under optimal conditions, the detection limits of 0.09 and 0.19 ng mL−1 were obtained with a relative standard deviation (RSD%) of 2.1–5.2% for Al3+ and Cr3+ ions, respectively. The enrichment factors were found to be 99 and 92 for Al3+ and Cr3+ ions, respectively. The effects of various cationic interferences on percent recovery of Al3+ and Cr3+ ions were studied. The developed method was successfully applied for selective extraction and preconcentration of trace amounts of Al3+ and Cr3+ in biological and environmental samples.

Novel ion imprinted polymer coated multiwalled carbon nanotubes as a high selective sorbent for determination of gold ions in environmental samples

In this work, for the first time an ion imprinted polymer (IIP) has been synthesized for gold ions preconcentration and determination. In order to increase extraction efficiency and improve the figures of merit, this polymer has been grafted on multiwalled carbon nanotube and was characterized by infrared (IR) spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), elemental analysis (CHN) and thermal analysis (TGA/DSC). The application of this sorbent has been investigated for rapid extraction, preconcentration and determination of trace amounts of gold ions in environmental samples. The optimum conditions, including pH of sample, eluent type and concentration, also eluent and sample flow rates and the least amounts of eluent for desorption of gold ions were obtained. The effects of various cationic interferences on the adsorption of gold ions, especially platinum and palladium ions, as the most important interferences, were evaluated. The analytical efficiency value of gold ions was 98.3% in the optimum condition. The limit of detection (LOD) was less than 0.041ngmL−1 for gold extraction. The maximum capacity of this IIP modified nano-tubes were obtained more than 67mgg−1. The relative standard deviation for this method was determined to be 1.14. Furthermore, the accuracy of this method was confirmed using various standard reference materials. This method was successfully applied for determination of gold ions in natural samples.

Tris(2‐Aminoethyl)Amine‐Functionalized Fe3O4 Magnetic Nanoparticles as a Selective Sorbent for Separation of Silver and Gold Ions in Different pHs

The usage of tris(2‐aminoethyl)amine‐functionalized Fe3O4 nanoparticles as a novel magnetic sorbent for rapid extraction, preconcentration, and determination of trace amounts of silver and gold ions was investigated. The optimum conditions for sample pH, eluent parameters (type, concentration and volume) were obtained. The effect of various cationic interferences on the adsorption of silver and gold was evaluated. The analytical efficiency values of both silver and gold ions were higher than 98.0% in the optimum conditions. The limits of detection (LOD) were less than 0.8 and 0.5 ng mL−1 for silver and gold, respectively. The linear ranges for silver and gold were 1.5–1000 ng mL−1 and 1.0–1000 ng mL−1 respectively. The maximum capacity of the modified magnetic nanoparticles was more than 97.3 mg g−1 and 167 mg g−1 for silver, and gold ions, respectively. The presented method was used to determine silver and gold ions in real samples. Finally, the method accuracy was confirmed by standard reference materials.

Surfactant mediated sulfide estimation at trace level: Application to environmental samples

A simple spectrophotometric method has been developed for the quantification of dissolved sulfide based on its reaction with ferric iron and the subsequent reaction of ferrous iron with 1-nitroso-2-naphthol in alkaline medium. The insoluble iron(II)-ligand complex has been solubilized in micellar medium using neutral surfactant which facilitates the non extraction step. The method obeys Beer’s law in the concentration range 0.5–8 μg in 10 mL of aqueous phase. The complex showed an absorption maximum at 710 nm with e value of 4.11 × 104 L/mol cm. The detection limit has been found to be 0.0036 μg/mL. The interference of common cations and anions has been studied and the proposed method has been successfully applied to determine the sulfide in different sewage water samples.

Pre-concentration of trace amounts of manganese in water samples based on (1-(2-pyridylazo)-2-naphthol) modified magnetic nanoparticles

A simple procedure based on magnetic nanoparticles has been developed for analytical purposes. In this method, 1-(2-pyridylazo)-2-naphthol (PAN)-modified magnetic nanoparticles (MNPs) were used for separation and pre-concentration of manganese(II) ions from aqueous samples. This method combines the use of a solution solvent with separation of magnetic nanoparticles from sample solution using a magnet. The influence of different parameters, such as amount of extractant (PAN) loaded on the nanoparticles, pH of solution, adsorption time, amount of modified nanoparticle, type and amount of eluents for desorption of manganese from magnetic nanoparticles were evaluated. The effect of various cationic and anionic interferences on the percentage recovery of manganese was also studied. Manganese ions were adsorped from a solution at pH 9.5 and desorbed from nanoparticles with 10 mL of DMSO : HNO3 (1 : 1, v/v). The detection limit of the proposed method was found to be 0.11 µg L−1. The method was employed to recover and determine the level of manganese in different water samples.

Chromatographic behavior and separation of pesticides on thin silica gel layers impregnated with cationic micelles

The chromatographic behavior of eight pesticides has been examined on cationic-micelles impregnated silica layers using mixed organic solvent (different combinations of hexane-acetone, v/v) systems. The chromatographic system constituting 0.01% CTAB (N-cetyl-N,N,N-trimethyl ammonium bromide) impregnated silica gel as stationary phase, and hexane-acetone in 1:1 ratio (v/v) as mobile phase was most favorable for on-plate identification of pesticides with preliminary separation. Surface modification of silica gel on impregnation, as indicated by SEM and FTIR studies was responsible for improved chromatographic performance. The results obtained on 0.01% CTAB impregnated silica layers were compared with those achieved on 0.01% CTAB impregnated kieselguhr, cellulose, or alumina layers. With selected chromatographic system, fivecomponent mixtures of pesticides (glyphosate, acephate, chlorpyrifos, malathion/methyl parathion, and isoproturon) were successfully resolved. The interference of metal cations as impurit...

Dual-Functional Gadolinium-Based Copper(II) Probe for Selective Magnetic Resonance Imaging and Fluorescence Sensing

A unique gadolinium complex, Nap-DO3A-Gd, comprising a naphthylamine luminescent moiety, a di-2-picolylamine (DPA) binding chelator, and a 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) moiety has been designed and synthesized as a dual-functional probe for selective magnetic resonance imaging and fluorescent sensing of copper(II) in living cells. Nap-DO3A-Gd exhibited a turn-on manner of relaxivity changes and a fluorescent quenching toward Cu(2+). Through the introduction of naphthalamide into the Gd(3+) contrast agent platform to restrict the coordination ability of the DPA chelator and with Gd(3+) coordinating to the DPA moiety to turn away the interferences of other metal cations from Cu(2+) detection, the probe featured selective relaxivity changes toward Cu(2+) over other metal ions and brought unique Cu(2+)-specific luminescent responses. The probe was water-soluble with the luminescent detection limit established at 6 ppb and was successfully used for luminescence imaging detection of copper(II) in living cells. The results demonstrated the efficiency and advantage of our approach in the development of a dual-modality image.

Novel magnetic ion imprinted polymer as a highly selective sorbent for extraction of gold ions in aqueous samples

In this work a novel ion imprinted polymer (IIP), based on dipyridyl amine-coated Fe3O4 nanoparticles (NPs), was synthesized as a novel magnetic sorbent for rapid extraction, preconcentration and determination of trace amounts of gold ions. This was characterized by IR spectroscopy, scanning electron microscopy (SEM), elemental analysis (CHN) and thermal analysis (TGA/DSC). The optimum conditions, including pH of sample, eluent type and concentration and also the least amount of eluent necessary for desorption of gold ions and the time of adsorption were obtained. The effect of various cationic interferences on the adsorption of gold, specifically Pt(II) and Pd(II) ions, were evaluated. The analytical efficiency and relative standard deviation values for the determination of gold ions were 98.6% and 1.08, respectively, under the optimum conditions. The limit of detection (LOD) was 0.43 ng mL−1 for gold extraction. The maximum capacity of the IIP modified magnetic nanoparticles was found to be greater than 76 mg g−1. Furthermore, the accuracy of this method was confirmed using various standard materials. This method was also applied successfully for preconcentration and determination of gold ions in some real samples.

Development of a Reliable Analytical Method for Liquid Anion-Exchange Extraction and Separation of Neodymium(III)

The liquid-liquid extraction of neodymium(III) from succinate media (0.06 M) has been studied at pH 6.0 with the solution of 0.1 M of N-n-octylaniline in xylene when equilibrium is maintained for 5 min. The back-extraction of neodymium(III) has been performed by using 0.1 M HClO4. The effect of various parameters, such as pH, equilibrium time, extractant concentration, stripping agents, organic diluents, and aqueous to organic volume ratio on the extraction of neodymium(III) has been studied. On the basis of slope analysis, the stoichiometry of the extracted species was determined as 1 : 1 : 2 [RR′NH2 +Nd(succinate)2 −](org). The method is free from interference of large number cations and anions. The method was used for the selective extraction of neodymium(III) from its binary mixture with U(VI), Zr(IV), Nb(V), La(III), Th(IV), Ce(IV), and Y(III). The proposed method is selective and was successfully applied to the synthetic mixtures to show the practical utility of the extractant.

Determination of cysteamine using label-free gold nanoparticles

Label-free gold nanoparticles were applied as a colorimetric probe for the determination of cysteamine. The approach is based on aggregation of the nanoparticles leading to a change in the absorption spectra and color of the solution. The influence of different factors (the presence of EDTA, pH, the concentrations of cysteamine and the nanoparticles) on the aggregation and analytical performance of the procedure was investigated. The potentiality of EDTA as a masking agent to eliminate the interference of metal cations was estimated. The method allows the determination of cysteamine with a detection limit of 0.01 μg mL−1. It was applied to the analysis of a hair-waving formulation and urine.

Polypyrrole-based bilayer nitrate amperometric biosensor with an integrated permselective poly- ortho-phenylenediamine layer for exclusion of inorganic interferences

A bilayer amperometric nitrate biosensor with an integrated permselective layer has been developed for exclusion of inorganic anion and cation interferences. The inner PPy(polypyrrole)–NaR–NADH layer of the biosensor is formed by galvanostatic polymerization of pyrrole (Py) in presence of nitrate reductase (NaR) and nicotinamide adenine dinucleotide (NADH), followed by formation of the outer permselective poly- ortho-phenylenediamine (P- o-PDA) layer by potentiodynamic polymerization of ortho-phenylenediamine ( o-PDA). The exclusion efficiency ( E eff) of the outer layer in rejecting inorganic cation and anion interferences is evaluated by a new proposed relationship. 73–87% and 47–84% of anion and cation interferences, respectively, were efficiently rejected with the permselective layer. Further improvement in the exclusion efficiency for cations was accomplished by combining the use of the outer layer with the addition of 1 mM EDTA into the measurement solution. The addition of EDTA improved the E eff achieved for cation rejection by 10–40% to give net E eff of 89–94%. The inclusion of the outer layer also aided the retention of NaR and NADH in the inner PPy–NaR–NADH layer and, hence, enabled improved amperometric detection of nitrate, achieving a detection limit of 0.20 μM and a linear concentration range of 10–500 μM with a 3.4% rsd ( n = 10).

Triphenyltetrazolium chloride as a new analytical reagent for molybdenum(VI): Application to plant analysis

Solvent extraction of molybdenum(VI) ion associate with triphenyltetrazolium chloride (TTC) has been studied. TTC was proposed as reagent for the spectrophotometric determination of micro amounts of molybdenum(VI) at λmax 250 nm. The optimum conditions for extraction of molybdenum(VI) as an ionassociation complex with TTC has been determined. Beer’s law is obeyed in the range of 0.5–10 μg/mL molybdenum(VI). The molar absorptivity of the ion-pair is 1 × 106 L/mol cm. The sensitivity of the method is 9.6 × 10−5 μg/cm2. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase are: distribution constant KD = 32.64, extraction constant Kex = 2.19 × 1010 association constant β = 6.71 × 108. The interferences of different cations, anions on molybdenum(VI) determination were also investigated. A sensitive and selective method for the determination of microquantities of molybdenum(VI) has been developed. The determination was carried out without preliminary separation of molybdenum. A novel procedure of molybdenum(VI) extraction and spectrophotometric determination in different plant samples was examined.

Extraction of Ultra Trace Amounts of Palladium on 9-Acridinylamine Functionalized SBA-15 and MCM-41 Nanoporous Silica Sorbents

The application of the modified MCM-41 and SBA-15 nanporous silicas in extraction of trace amounts of palladium is investigated and developed. Surface of nanoporous silicas, MCM-41 and SBA-15, were modified with 9-acridinylamine ligand and then utilized as solid-phase sorbents for the extraction of palladium. Different experimental conditions such as pH, flow rates of the sample, and eluent solution were studied. The type and the smallest amount of eluent for elution were optimized and the breakthrough volume and the influence of various cationic interferences on the adsorption was investigated. The recovery values in this method are greater than 95% and 98.5%. The obtained limits of detections (LOD) are lower than 0.17 ng mL−1 and 0.15 ng mL−1 for SBA-15 and MCM-41, respectively. The pre-concentration factors were calculated to be more than 193 and 187.5 for SBA-15 and MCM-41, respectively. The relative standard deviations (RSD) of the method are lower than 4% and 1.5%, and the adsorption capacities were also obtained to be more than 170 mg g−1 and 195 mg g−1 for SBA-15 and MCM-41, respectively. The proposed procedure was applied on real samples and the amount of palladium was successfully derived.

Determination of As(III) by anodic stripping voltammetry using a lateral gold electrode: Experimental conditions, electron transfer and monitoring of electrode surface

The aim of this work is to evaluate the efficiency of the determination of As(III) by anodic stripping voltammetry (ASV) using a lateral gold electrode and to study the modifications of the electrode surface during use. Potential waveforms (differential pulse and square wave), potential scan parameters, deposition time, deposition potential and surface cleaning procedure were examined for they effect on arsenic peak intensity and shape. The best responses were obtained with differential pulse potential wave form and diluted 0.25M HCl as supporting electrolyte. The repeatability, linearity, accuracy and detection limit of the procedure and the interferences of cations and anions in solution were evaluated. The applicability of the procedure for As(III) determination in drinking waters was tested. Cyclic voltammetry (CV) was used to study the electrochemical behaviour of As(III) and for the daily monitoring of electrode surface. Also scanning electron microscopy (SEM) analysis was used to control the electron surface. Finally we evaluated the possibility to apply the equations valid for flow systems also to a stirred system, in order to calculate the number of electrons transferred per molecule during the stripping step.

A rapid extractive spectrophotometric determination of copper(II) in environmental samples, alloys, complexes and pharmaceutical samples using 4-N,N(dimethyl)amino]benzaldehyde thiosemicarbazone

4-[N,N-(Dimethyl)amino]benzaldehyde thiosemicarbazone (DMABT) is proposed as an analytical reagent for the extractive spectrophotometric determination of copper(II). DMABT forms yellow colored complex with copper(II) in the pH range 4.4-5.4. Beer's law is obeyed in the concentration range up to 4.7 μg mL(-1). The optimum concentration range for minimum photometric error as determined by Ringbom plot method is 1.2-3.8 μg mL(-1). The yellowish Cu(II)-DMABT complex shows a maximum absorbance at 420 nm, with molar absorptivity of 1.72 × 10(4)dm(3) mol(-1) cm(-1) and Sandell's sensitivity of the complex obtained from Beer's data is 0.0036 μg cm(-2). The composition of the Cu(II)-DMABT complex is found to be 1:2 (M/L). The interference of various cations and anions in the method were studied. Thus the method can be employed for the determination of trace amount of copper(II) in water, alloys and other natural samples of significant importance.