A sequential injection method for the determination of aluminum in drinking water using fluorescence enhancement of the aluminum-morin complex in micellar media

A robust and simple sequential injection (SI) method for the assay of aluminum ions in natural water is described. The method is based on the enhancement of the fluorescence of the aluminum-morin complex in the presence of a non-ionic surfactant (Tween-20). The fluorescence of the complex is monitored at an emission wavelength of 495 nm with excitation at 425 nm. The pH, morin concentration and the aspirated sample volume were optimized simultaneously using a chemometric method. The optimum operating conditions are: 150 μl aspirated sample volume, 20 μM morin concentration, a pH of 4.5 and 0.8% Tween-20. Using these optimum conditions a linear calibration curve was obtained from 50 to 1000 ppb. The detection limit was 3 ppb and the maximum relative standard deviation (n=5) of the method was 2.9%. The method was successfully applied for the determination of aluminum ions in natural water samples.     

Silver nanoparticles capped with 8-hydroxyquinoline-5-sulfonate for the determination of trace aluminum in water samples and for intracellular fluorescence imaging

We report on a simple method for the determination of traces of aluminum(III) in water at pH 7.4 by using silver nanoparticles (Ag-NPs) functionalized with 8-hydroxyquinoline-5-sulfonate. The modified Ag-NPs undergo (a) a distinct color change from yellow to deep orange, and (b) a strong fluorescence enhancement upon addition of Al(III). Both the ratio of absorbances at 530 and 392 nm, and the intensity of fluorescence at 492 nm can serve as the analytical information. The absorption-based calibration plot increases linearly in the 0.1 to 4.0 μM Al(III) concentration range. The detection limit is 2.0 nM which is much lower than the permissible level (7.4 μM) for drinking water as defined by the World Health Organization. The method was successfully applied to the determination of Al(III) in samples of lake water, tap water and boiler water, and the recoveries were from 98 to 105 %. The assay also was applied to the determination of Al(III) in living mouse myeloma cells via fluorescence imaging. A linear relationship was obtained between relative fluorescence intensity (F/F₀) and the concentration of Al(III) in the 0.05 μM to 4 μM concentration range. The detection limit is 15 nM.

A sequential injection method for the fluorimetric determination of aluminum in drinking water using 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid

A robust and simple sequential injection (SI) method for the assay of aluminum ions in drinking water is described. The method is based on the complex formation between aluminum and 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid (HSNQ). The fluorescence of the complex is monitored at an emission wavelength of 492 nm with excitation at 357 nm. The HSNQ concentration, aspirated reagent and sample volumes were optimized simultaneously using 3(3) full factorial design. The optimum operating conditions are aspirated sample and reagent volumes of 90 and 70 microL, respectively, and HSNQ concentration of 20 microM. With these conditions linear calibration curves were obtained from 100 to 800 ppb. The detection limit was 4 ppb. The maximum relative standard deviation of the method was 1.43% (n=5). The method was successfully applied for the determination of aluminum in drinking water samples.     

Spectrofluorimetric determination of trace aluminum in diluted hemodialysis solutions

In this study, a spectrofluorimetric method has been developed for the determination of aluminum based on the formation of an aluminum complex with N,N'-disalicylidene-1,3-diamino-2-hydroxypropane (DSAHP). The most suitable pH, solvent medium, complex formation time, Schiff base concentration and temperature were determined. The excitation and emission wavelengths were 270 and 437 nm, respectively, in which the DSAHP-Al complex gave the maximum fluorescence intensity at pH 3.0 and 6.0 in 50% dioxan-50% water medium. Under these conditions, calibration curves were obtained in three different linear limits, and was found that aluminum could be detected within the concentration limit of 0-10.0 microM and the lowest detection limit being 0.27 ng ml(-1). The stoichiometry of the DSAHP-Al complex was also determined spectrofluorimetrically under optimal conditions and the molar ratio of DSAHP-Al was calculated as 2:1. Using the developed method, aluminum was detected in hemodialysis solutions, and the results obtained were similar and comparable with those obtained using the method described in the British Pharmacopoeia within 95% confidence limits. This method can be used successfully for the routine determination of aluminum because it is quick, requires less amount of reactives, is sensitive, reliable and reproducible.     

Determination of Coenzyme II Using Balofloxacin–Terbium(III) as a Fluorescence Probe by Spectrofluorometry

Abstract

A new spectrofluorometric method was developed for determination of coenzyme II. We studied the interactions between balofloxacin–terbium(III) complex and coenzyme II by using ultraviolet–visible absorption and fluorescence spectra. While balofloxacin–terbium(III) was used as a fluorescence probe, under the optimum conditions, coenzyme II could remarkably enhance the fluorescence intensity of the balofloxacin–terbium(III) complex at λ = 545 nm, and the enhanced fluorescence intensity was in proportion to the concentration of coenzyme II. Optimum conditions for the determination of coenzyme II were also investigated. The dynamic range for the determination of coenzyme II was 6.0 × 10^?8 to 6.0 × 10^?6 mol L^?1, and the detection limit (3σ/k) was 3.5 × 10^?8 mol L^?1. This method was simple, practical, and relatively free interference from coexisting substances and could be successfully applied to determination of coenzyme II in synthetic samples. The mechanism of fluorescence enhancement of balofloxacin–terbium(III) complex by coenzyme II was also discussed.     

Highly Sensitive Spectrofluorimetric Determination of Trace Amounts of Superoxide Dismutase Using a Prulifloxacin-Terbium(III) Probe

Abstract

A new spectrofluorimetric method was developed for determining superoxide dismutase. The interactions between prulifloxacin (PUFX) –Tb³⁺ complex and superoxide dismutase had been studied by using UV-Vis absorption and fluorescence spectra. Using prulifloxacin–Tb³⁺ as a fluorescence probe, under optimum conditions, superoxide dismutase could remarkably enhance the fluorescence intensity of the prulifloxacin–Tb³⁺ complex at λ = 545 nm, and the enhanced fluorescence intensity was in proportion to the concentration of superoxide dismutase. Optimum conditions for the determination of superoxide dismutase were also investigated. The dynamic range for the determination of superoxide dismutase was 0.032 to 22.56 µg mL^?1, and the detection limit (S/N = 3) was 1.5 ng 4 mL^?1. This method was simple, practical, and relatively free of interference from coexisting substances and could be successfully used to determine superoxide dismutase in the plant and blood samples. The mechanism of fluorescence enhancement of prulifloxacin–Tb³⁺ complex by superoxide dismutase was also discussed.     

Fluorimetric Determination of Gatifloxacin in Aqueous,Pure and Pharmaceutical Formulations

Abstract

A spectrofluorimetric method was developed for the determination of gatifloxacin. The emission peak for gatifloxacin was recorded at 495 nm upon excitation at 291 nm. The fluorescence process was pH dependent. The dynamic range for the method was 16–80 ng ml^?1with detection limit of 3.97 ng ml^?1. A linear relationship between the fluorescence intensity and the concentration of gatifloxacin solution was obtained with r ² of 0.9968. The method has successfully applied to the determination of gatifloxacin in pure, authentic and aqueous samples.     

Glassy Carbon Electrode Modified with Citrate Stabilized Gold Nanoparticles for Sensitive Arsenic (III) Detection

The electrochemical detection of As(III) was investigated on the novel citrate stabilized gold nanoparticle modified glassy carbon electrode (AuNPs/GCE) in 1 M HCl by square wave anodic stripping voltammetry. AuNPs/GCE was prepared by simply casting citrate stabilized gold nanoparticles onto the well-polished glassy carbon electrode. Gold modification was evaluated by cyclic voltammetry, while transmission electron microscopy and UV-vis Spectroscopy revealed the size and distribution of gold nanoparticles. Anodic stripping voltammetry was performed with the modified electrode in As(III) solution. Electrochemical experiments proved that AuNPS/GCE exhibited good performance for As(III) analysis, the linear range were obtained between 0.05 and 1 ppb for trace level of As(III) as well as 1 to 15 ppb, with a limit of detection of 0.025 ppb. In terms of reproducibility, the precision of the aforementioned method in %RSD was calculated at 7.78% (n = 10), and the repeatability of the proposed method was calculated to be 1.59%. The application of the method to analyze As(III) in tap water was investigated.     

钙黄绿素荧光法测定痕量钇(Ⅲ)

研究了钙黄绿素荧光法测定Y(Ⅲ)。在pH 8.0的H3BO3-Na2B4O7缓冲溶液和表面活性剂Tween 80的存在下,痕量Y(Ⅲ)能与钙黄绿素反应形成配合物,使体系的荧光强度显著增加,体系的激发和发射波长分别为492和512nm,Y(Ⅲ)的质量浓度在0～2.0μg/mL范围内与△F成良好的线性关系,其线性回归方程为:△F=3.2648+2.384ρ(μg/mL),相关系数r=0.9961,检出限为0.023μg/mL。方法用于乙酸铈中痕量钇(Ⅲ)的测定,测定结果与ICP-AES法相符,加标回收率在96.3%～103.0%之间。     

On-line aluminium preconcentration on chelating resin and its FIA-spectrofluorimetric determination in foods and dialysis concentrates

A new, sensitive and rapid spectrofluorimetric flow-injection method, is presented for the determination of trace levels of aluminium based on the formation of a fluorescent complex between aluminium and 5,7-dibromo-8-quinolinol (DBQ) and its extraction into diethylether (λ_exc = 400 nm, λ_em = 525 nm). Experimental conditions such as pH, reagent concentration, flow-rates, sample volume, extraction coil length, etc., have been optimized for on-line and batch procedures. The detection limits are 1 ppb and 0.3 ppb for batch and on-line systems respectively. The coeflicient of variation is 3.0% at the 4 ppb level for the FIA system. To remove interferences and to preconcentrate aluminium, a chelating resin microcolumn which was able to selectively complex A1(III) and was obtained by immobilizing Chromotrope 2B on AG1-X8 ion-exchange resin, was incorporated into the FIA system. The proposed method was successfully applied to determine aluminium in tap water, food samples and dialysis solutions.     

Potentiometric Dipyridamole Sensors Based on Lipophilic Ion Pair Complexes and Native Ionic Polymer Membranes

Abstract

A new spectrofluorimetric method was developed for the determination of trace amounts of lecithin. Using enoxacine (ENX)‐terbium ion (Tb³⁺) as a fluorescent probe, in a buffer solution at pH=5.80, lecithin can remarkably reduce the fluorescence intensity of the ENX‐Tb³⁺ complex at λ=545 nm; the reduced fluorescence intensity of the Tb³⁺ ion is proportional to the concentration of lecithin. Optimum conditions for the determination of lecithin were also investigated. The linear range and detection limit for the determination of lecithin were 1.96×10^?7–9.8×10^?6 mol l^?1 and 9.74×10^?8 mol l^?1. This method is simple, practical and relatively free of interference from coexisting substances, and can be successfully applied to assess lecithin in serum samples.     

Highly Sensitive Spectrofluorimetric Determination of Trace Amounts of Folic Acid using a Oxytetracycline-Terbium(III) Probe

Abstract

A new spectrofluorimetric method was developed for the determination of trace amounts of folic acid using oxytetracycline–terbium ion complex as a fluorescent probe. In the buffer solution of pH 6.00, folic acid remarkably reduced the fluorescence intensity of the oxytetracycline–terbium complex at λ = 545 nm. The reduced fluorescence intensity of the Tb³⁺ ion was proportional to the concentration of folic acid. Optimum conditions for the determination of folic acid were investigated. This method was simple, practical, and relatively free of interference from coexisting substances. Furthermore, it was successfully applied to assess folic acid in tablet, injection, and urine samples.     

Synthesis of nano-pore size Al(III)-imprinted polymer for the extraction and preconcentration of aluminum ions

In this study, an ion imprinted polymer (IIP) was prepared for the selective separation and preconcentration of trace levels of aluminum. Al(III) IIP was synthesized in the presence of Al(III)-8-hydroxyquinoline (oxine) complex using styrene and ethylene glycol dimethacrylate as a monomer and crosslinker, respectively. The imprinted Al(III) ions were completely removed by leaching the IIP with HCl (50 % v/v) and were characterized by FTIR and scanning electron microscopy. The maximum sorption capacity for Al(III) ions was found to be 3.1 mg g^?1 at pH 6.0. Variables affecting the IIP solid phase extraction were optimized by the univariable method. Under the optimized conditions, a sample volume of 400 mL resulted in an enhancement factor of 194. The detection limit (defined as 3 S _b/m) was found to be 1.6 μg L^?1. The method was successfully applied to the determination of aluminum in natural water, fruit juice and cow milk samples.     

Sensitive spectrofluorimetric determination of aluminium(III) with Eriochrome Red B

A spectrofluorimetric method is reported for the determination of Al(III), based on the formation of a fluorescent Al(III)-Eriochrome Red B complex in the presence of hexamethylenetetramine at 60°C. Fluorescence measurements were made at 2°C and all variables that affect the development of the complex are reported. The method is very selective and the detection limit is 0.1 ng ml^?1. It was applied to the determination of Al(III) in tap water.     

Determination of trace europium based on new fluorimetric system of europium(III) with thenoyltrifluoroacetone and N,N'-dinaphthyl-N,N'-diphenyl-3,6-dioxaoctanediamide

In the present paper, N,N'-dinaphthyl-N,N'-diphenyl-3,6-dioxaoctanediamide acts as a specific reagent for enhancing the fluorescence intensity of Eu(III) complex with thenoyl trifluoroacetone (TTA), the spectrofluorimetric determination of trace amounts of Eu(III) based on the above system was carried out and its luminescence mechanism was studied. The excitation and emission wavelengths are 343.6 and 613.3 nm, respectively. The fluorescence intensities vary linearly with the concentration of europium(III) in the range 3.647x10(-3)-3.039 mug ml(-1) for the original fluorescence with a detection limit down to 2.279x10(-4) mug ml(-1) and the standard deviation is 0.063 mug ml(-1) for 10 times measurements, and in the range 7.598x10(-4)-0.0243 mug ml(-1) (SD=0.035 for 15 times measurements), 0.06078-0.6100 mug ml(-1) (SD=0.52 for 10 times measurements) for the first derivative fluorescence signal with a detection limit down to 8.566x10(-5) mug ml(-1). The interferences of other rare earths and some of inorganic ions are described. This method is a direct, rapid, selective and sensitive analytical method for the determination of trivalent europium in rare earth ore samples and high purity of rare earth oxides.     

Development and Application of a Hydride Generation Laser Induced Fluorescence Method for Measurements of Bismuth

A hydride generation laser induced fluorescence (HG LIF) approach has been investigated for trace level measurements of bismuth. The technique uses a tunable dye laser operating at 306.7 nm as the excitation source and bismuth fluorescence is measured at 472 nm. The optimized HCl and NaBH₄ concentrations for bismuth measurements were 1.2 M and 2.0%, respectively. The current technique has a limit of detection of 0.03 ppb and 0.01 ppb for blank measurements performed with the laser tuned on and off the bismuth excitation wavelength, respectively. Measurements of bismuth in different sample matrices have demonstrated the effectiveness of thiourea and ascorbic acid as masking agents for measuring samples containing interfering ions. Measurements of bismuth have been performed in reference materials, a bismuth-containing medication, and tea leaves. The results demonstrate that the HG LIF approach has feasibility for measuring bismuth in various samples at environmentally relevant concentrations.     

Silica nanoparticles doped with an iridium(III) complex for rapid and fluorometric detection of cyanide

We describe a nanosensor for sensitive and selective detection of cyanide anions. The Ir(III) chlorine bridge complex [Ir(C^N)₂-m-Cl]₂ (Irpq, where pq is C^N = 2-phenyl quinoline) was doped into silica nanoparticles (SiNPs) with a typical size of about 30 nm. The intensity of the yellow emission of the doped SiNPs (under 410 nm exCitation) was strongly enhanced on addition of cyanide ions due to the replacement of chloride by cyanide. The method can detect cyanide ions in the 12.5 to 113 μM concentration range, and the limit of detection is 1.66 μM (at an S/N ratio of 3). The method is simple, sensitive and fast, and this makes it a candidate probe for the fast optical determination of cyanide.

The nanosensor is exploiting the cyanide-induced enhancement of the fluorescence of silica nanoparticles doped with an Ir(III) complex which is the result of the replacement of chloride by cyanide.

     

Selective Second Order Derivative Spectrophotometric Method for the Determination of Gallium(III) in Presence of Large Excess of Indium(III)

Abstract

A simple, sensitive, and selective second order derivative spectrophotometric method is proposed for the determination of microgram quantities of gallium(III) especially in presence of large excess of indium(III). Ga(III) reacts with 2‐hydroxy‐3‐methoxy benzaldehyde isonicotinoylhydrazone (HMBAINH) chromogene forming an intense greenish yellow coloured soluble complex in acidic buffers and in presence of 0.2% of triton X‐100. The complex showed maximum absorption at 405 nm and at pH 5.0, where the reagent has negligible absorbance. A second order derivative spectrum of the complex solution showed maximum derivative amplitude at 415 nm and again at 460 nm with a zero cross at 442 nm. Beer's law was obeyed in the concentration range 0.036–1.533 µg/ml and 0.070–1.533 µg/ml of Ga(III) at 415 nm and 460 nm, respectively. However, at 404 nm In(III)‐HMBAINH complex showed zero amplitude in the second order derivative spectrum where Ga(III)‐HMBAINH obeyed Beer's law in the range of 0.070–1.394 µg/ml. This allows determination of Ga(III) in presence of large excess of In(III) by second order derivative spectrophotometry. The tolerance limits of other diverse ions and other analytical parameters were also evaluated. The method was applied for the determination of gallium in some synthetic mixtures containing indium.     

Catalytic flow-injection determination of sub-ppb copper(II) using the redox reaction of cysteine with iron(III) in the presence of 2,4,6-tris(2-pyridyl)-1,3,5-triazine.

A kinetic-catalytic spectrophotometric flow-injection method was developed for the rapid and sensitive determination of trace amounts of copper(II). The method is based on the catalytic effect of copper(II) on the redox reaction of cysteine with iron(III). Iron(II) produced by the catalytic reaction reacts with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) to form the iron(II)-TPTZ complex (lambda(max) = 593 nm). By measuring an absorbance of the complex, one could determine 0.05-8 ppb copper(II) with the relative standard deviations (n = 10) of 1.6%, 1.3%, and 0.8% for 0.5 ppb, 1 ppb, and 2 ppb copper(II), respectively. The limit of detection (S/N = 3) was 0.005 ppb. The sample throughput was 30 h(-1). The proposed method was successfully applied to the determination of copper in natural water and serum samples.     

Phthalocyanine-based fluorescent chemosensor for the sensing of Zn (II) in dimethyl sulfoxide-acetonitrile

A tetra-substituted phthalocyanine based on 4-[2-(4-nitrophenoxy)ethoxy]phthalonitrile carrying nitrophenyl group for the sensing of Zn²⁺ has been prepared and characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR, and MS spectral data. The sensing of Zn²⁺ is based on the fluorescence quenching of Pc. Both absorbance and fluorescence spectra of ZnPc exhibit distinct changes in visible region in response to treatment with Zn²⁺ ion in dimethyl sulfoxide. The fluorescence spectrum of the ligand showed quenching in the intensity of the signal at 688?nm for Zn²⁺. The complex composition of ZnPc was found 1:1 by means of spectrophotometric and spectrofluorimetric titration data. The spectrofluorimetric method showed good sensitivity for Zn²⁺ with linear range and detection limit of 4.0?×?10^?6–4.4?×?10^?5 and 2.4×10^?7?M, respectively.