Study on the Fluorescence System of Oxolinic Acid‐Tb(III) and the Determination of Oxolinic Acid

Abstract

In Tris‐HCl buffer (pH=7.43), Tb³⁺ can react with oxolinic acid (OA) and form a 1:2 complex, which emits the intrinsic fluorescence of Tb³⁺. Based on this, a new fluorimetric method of determination of OA is developed. Under the optimum conditions, the enhanced fluorescence intensity of the system is proportional to the concentration of OA in the range of 1.5×10^?7～2.5×10^?5mol/L, and the detection limit is 5.5×10^?9 mol/L. Recovery test was also satisfactory. The experiments indicated that the luminescence mechanism was attributed to the M*–M luminescence.     

Fluorescence enhancement by gadolinium of the europium or samarium-dibenzoylmethane-diethylamine system

A fluorescence enhancement produced by adding Gd³⁺, Y³⁺, Tb³⁺, La³⁺ or Lu³⁺ to europium or samarium-dibenzoylmethane-diethylamine was observed. Gd³⁺ enhanced the fluorescence intensity by 2–3 orders of magnitude compared with the system without Gd³⁺. The new system was used for the simultaneous determination of traces of Sm³⁺ and Eu³⁺ in the ranges 1.0 × 10^?9?8.0 × 10^?8 M and 1.0 × 10^?11?4.0 × 10^?9 M, respectively, and the detection limits were 5 × 10^?13 M for Sm³⁺ and 8 × 10^?14 M for Eu³⁺. The luminescence mechanism of the system is discussed.     

Study of Fluorescence System of Gmanylic Acid-Tb3+ and the Determination of Gmanylic Acid

Abstract

It was found that gmanylic acid (GMP) can be selectively completed with Tb³⁺ at pH 6.0-6.6, which then emits strong fluorescence characteristic of Tb³⁺. This reaction can be used for the determination of GMP in presence of adenylic acid (AMP), uridylic acid (UMP) and cylidylic acid (CMP). A linear relationship is obtained between the fluorescence intensity and GMP concentration in the range of 2.0×10^?7 - 1.0×10^?4M. The detection limit is 2.0×10^?8 M. The results showed that the composition ratio and apparent stability constant of GMP-Tb complex were 1:1 for GMP Tb³⁺- and 2.3×10^?5, respectively.     

Fluorescence enhancement of the europium-yttrium-diphacinone-ammonia system

A study of the enhanced (ca. 100 ×) fluorescence intensity of the Eu³⁺-diphacinone-ammonia system by Y³⁺ was made using a colloidal suspension. The excitation and emission wavelengths were 330 and 612 nm, respectively. The fluorescence intensity was a linear function of the concentration of europium in the range 6.0 × 10^?11–8.0 × 10^?7 M. The detection limit was 8.0 × 10^?14 M. The standard addition method was used for the determination of europium in rare earth oxides, with satisfactory results.     

Enhanced Luminescence of Europium by Gadolinium and Its Application

Abstract

The fluorescence enhancement of the Eu-dibenzoylmethane(DBM)- cetylpyridinium-chloride (CPC) system was studied. The fluorescence intensity of the system can be greatly increased by Gd³⁺ in the presence of triethanolamine(TEA). The optimum conditions for enhanced fluorescence of the Eu-Gd-DBM-CPC system were examined. It was a linear function of the Eu³⁺ concentration in the range of 1.0×10^?10～1.0×10^?8 mol dm^?3 under the optimized conditions. The detection limit was 2.6 × 10¹¹ mol dm^?3 in an aqueous solution at pH=7.5～9.5.

The Eu-Gd-DBM-CPC system was applied to the determination of europium in rare earth oxides with satisfactory results. The mechanism of enhanced fluorescence was discussed.     

A Fluorescence Quenching Method for the Determination of Chromium(VI) with L-Tyrosine

Abstract

A fluorescence quenching method for the determination of Cr(VI) in aqueous solution is described. The fluorescence intensity of the system is linear ever the range 5×10^?6 - 1.0×10^?4 M Cr(VI). The method has been applied to the determination of Cr(VI) In cast iron and waste water.     

Fluorescence Enhancement of Rare Earths by Yttrium and its Application

Abstract

A study of the enhancement effect on the fluorescence intensity of the Eu³⁺–-thenoyltrifluoroacetone (TTA)–-cetyltri–-methylammonium bromide (CTMAB) and the Dy³⁺ pyrocatechol–-3,5-disulphonic acid (Tiron) systems by Y³⁺has been carried out. In the presence of yttrium the fluorescence intensity of the systems was enhanced by a factor of about 100 and 15, respectively. The fluorescence intensity was a linear function of the concentration of europium or dysprosium in the range 1.0 × 10^?10–-1.0 × 10^?8mol dm^?3 and 8.0 × 10^?8–-9.0 × 10^?6mol dm^?3, respectively. The detection limit was 1.0 × 10^?11mol dm^?3 and 1.0 × 10^?10mol dm^?3, respectively. The standard addition method was used for the determination of europium or dysprosium in rare earth oxides and gave satisfactory results. The mechanism of enhanced fluorescence was proposed.     

Room Temperature Phosphorescence Optosensor for Terbium

Abstract

A solid surface room temperature phosphorescence optosensing method has been developed for the determination of terbium(III) based on the adsorption of its binary complex with 1,4-bis (l'-phenyl-3′-methyl-5′-pyrazolone-4′-) butanedione-(1,4) (BPMPBD) onto the hydrogen form of a strong cation exchange resin packed in a flow cell in an aqueous flow system. The phosphorescence intensity is a linear function of the concentration of terbium in the range of 8x10^?9 M-6x10^?7 M, and the detection limit is 3x10^?9 M terbium. The response mechanism was also studied. The present optosensor has been used for the determination of trace amounts of terbium in synthetic samples with satisfactory results.     

A ratiometric fluorescent probe for zinc ions based on the quinoline fluorophore

A ratiometric fluorescent zinc probe 1 of carboxamidoquinoline with a carboxylic acid group was designed and synthesised. Probe 1 exhibits high selectivity for sensing Zn²⁺; about a 13-fold increase in fluorescence emission intensity and an 82?nm red-shift of fluorescence emission are observed upon binding Zn²⁺ in EtOH/H₂O (1?:?1, V/V) solution. The ratiometric fluorescence response is attributed to the 1?:?1 complex formation between probe 1 and Zn²⁺ which has been utilised as the basis for the selective detection of Zn²⁺. The analytical performance characteristics of the proposed Zn²⁺-sensitive probe were investigated. The linear response range covers a concentration range of Zn²⁺ from 2.0?×?10^?6 to 5.0?×?10^?5?mol?L^?1 and the detection limit is 2.7?×?10^?7?mol?L^?1. The determination of Zn²⁺ in both tap and river water samples shows satisfactory results.     

Fluorescence enhancement of the Eu-Tb-benzoylacetone-phenanthroline system

The Eu-benzoylacetone-phenanthroline system, which has strong fluorescence intensity, was studied. It was found that the fluorescence intensity can be greatly increased by La, Gd, Tb, Lu and Y, Tb giving the greatest enhancement (ca. two orders of magnitude). The maximum fluorescence intensity was obtained at pH 8.0. Beer's law was obeyed from 1.0 × 10^?9 to 2.0 × 10^?7 M Eu. The detection limit for europium was 2.0 × 10^?11 M.     

Study on the co-luminescence system Sm-Gd-BPMPHD-CTMAB and its analytical application

It has been found that the Sm-BPMPHD-CTMAB ion association system shows a strong fluorescence intensity. In this system some rare earth ions, such as Lu³⁺, Y³⁺, Gd³⁺ and Tb³⁺, exert an evident fluorescence enhancement effect. The formation conditions of the system and the factors affecting the columinescence effect were studied in detail in order to determine trace amounts of Sm³⁺. Under optimum conditions a linear relationship was obtained between the fluorescence intensity and the Sm³⁺ concentration in the range of 5.0×10^?8–8.0×10^?6 mol·L^?1. The detection limit of Sm³⁺ was 2.0×10^?8 mol·L^?1. The determination gave satisfactory results.     

Sensitive Determination of Prulifloxacin by Its Fluorescence Enhancement on Terbium(III)–Sodium Dodecylbenzene Sulfonate System

Abstract

A terbium-sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of prulifloxacin (PUFX). It was found that SDBS significantly enhanced the fluorescence intensity of the PUFX–Tb³⁺ complex (about 13-fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 290 nm and 545 nm, pH 8.0, 4.0 × 10^?5 mol L^?1 terbium(III), and 4.0 × 10^?4 mol L^?1 SDBS. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of PUFX over the range 6.0 × 10^?8 to 2.0 × 10^?6mol L^?1 with a correlation coefficient of 0.9991. The detection limit (S/N = 3) was determined as 8.5 × 10^?9 mol L^?1. This method has been successfully applied for the determination of PUFX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range, and good stability. The luminescence mechanism of the system was also discussed in detail. In the fluorescence system of PUFX–Tb³⁺–SDBS, SDBS acted not only as the surfactant but also as the energy donor.     

Flow Injection Chemiluminescence Determination of Etamsylate with Electrogenerated Hypochlorite

Abstract

A fast and simple electrogenerated unstable reagent chemiluminescence system for flow injection analysis of etamsylate is described, based on a decrease in the chemiluminescence intensity from the luminol-hypochlorite system. The response is linear to the concentration of etamsylate in the range from 1x10⁹ to 8x 10^?9. The detection limit is 6 x 10^?10 g ml^?1. The relative standard deviation is 3.1% at 2 x 10^?9 g ml^?1 (n=7). The proposed method is suitable for automatic and continuous analysis and has been successfully tested for determination of etamsylate in pharmaceutical formulations.

     

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.     

Spectrofluorimetric method for the determination of uric acid in human serum

A new spectrofluorimetric method is described for the determination of uric acid (UA), that can remarkably reduce the fluorescence intensity of the enoxacin (ENX)-terbium ion (Tb³⁺) complex at 545 nm. The reduced fluorescence intensity of Tb³⁺ ion at pH 5.7 is proportional to the concentration of UA. Optimum conditions for the determination of UA have been investigated. The linear range and detection limit for the determination of UA are 6.0 × 10^?7–3.0 × 10^?5 M and 1 × 10^?7 M, respectively. The relative standard deviation (RSD) was 0.4% for 6 × 10^?6 M UA (n = 11). The method is simple, practical and relatively free of interferences. It has been successfully applied to assess UA in serum at the level of 3 × 10^?4 M with an RSD of 5–7% (n = 3). The results were evaluated by comparison with a common clinical spectrophotometric method using phosphotungstic acid as developer.     

Photometric Detection Inside the Stream of Sample Sheath Fluid

Abstract

Photometric detection with continuous feed of reagent into the centre of sample flow is described. Performance characteristics of this technique were tested at models without and with chemical reaction. Linear calibration curves were obtained for methylorange (5 x 10^?6 - 1 x 10^?4 M) and for ammonia reaction with the Nessler's reagent (6 x 10^?6 6 x 10^?4 M). The technique was applied for the determination of ammonia in drinking water. In this case, the preconcentration step was necessary.     

A new lawsone azo-dye for optical sensing of Fe3+ and Cu2+ and their DFT study

A new lawsone-based azo-dye 2-hydroxy-3-((pyridin-2-ylmethyl)diazenyl)naphthalene-1,4-dione (1) was synthesized and applied for sensing of metal ions. Receptor 1 showed selective fluorescent and colorimetric response for the detection of Cu²⁺ and Fe³⁺ over other tested metal ions. The fluorescence intensity of 1 was significantly quenched allowing detection of Fe³⁺ and Cu²⁺ down to 0.61 and 6.06 μM, respectively. The binding has been established by fluorescence spectroscopic method. Receptor 1 provided a 1?:?1 binding scaffold for recognition of Fe³⁺ and Cu²⁺ ions with the association constant of 3.33 × 10⁶ and 3.33 × 10⁵ M^?1, respectively. The B3LYP/6-31G/LANL2DZ method was employed for the optimization of 1 and 1·Fe³⁺ and 1·Cu²⁺.     

Perimedine-linked rhodamine dye in visual sensing of Al3+, Fe3+ and Fe2+ ions in aqueous organic medium under different experimental conditions

ABSTRACT

Perimedine labelled rhodamine dye 1 has been designed and synthesised. Metal ion binding studies of 1 have been performed in CH₃CN/H₂O (3:1, v/v, 10 mM Tris-HCl buffer, pH = 6.90). Compound 1 senses multiple metal ions such as Al³⁺, Fe³⁺ and Fe²⁺ by exhibiting turn on fluorescence and colour change (colourless to pink) under different experimental conditions. Concentration variation distinguishes Al³⁺ from Fe³⁺ ion. At low concentration (c = 1 x 10^?4 M), only Al³⁺ ion can exhibit turn on fluorescence with sharp colour change. Sensing of Fe²⁺ ion through turn on fluorescence and colour change has been possible via in situ oxidation by following Fenton’s reaction.     

A biacylhydrazone-based chemosensor for fluorescence ‘turn-on’ detection of Al3+ with high selectivity and sensitivity

A simple Al³⁺ fluorescent chemosensor (1) based on diacylhydrazone has been designed and synthesized by the condensation reaction of 2-hydroxy naphthaldehyde and metaphthalic hydrazide. The chemosensor 1 displays a specific and sensitive response to Al³⁺ over other cations in DMSO solution. Upon the addition of DMSO solution of Al³⁺, the sensor 1 shows an immediate fluorescence ‘turn-on’ response and emitting strong blue emission with visible color change from colorless to green. The fluorescence quantum yield enhanced from 7.24% to 48.68%. Meanwhile, the fluorescence and UV absorption spectra detection limits of the chemosensor 1 for Al³⁺ were 2.0 × 10^?7 M and 5.6 × 10^?7 M respectively, indicating the high sensitivity of 1 to Al³⁺. Furthermore, test strips based on 1 were fabricated, which could be used as a convenient test kit for the detection of Al³⁺ and an efficient Al³⁺ controlled fluorescent security display materials.     

Study on a Fluorometric Method for the Determination of Protein in Serum Using Quercetin‐Lanthanum (III)‐Sodium Dodecyl Benzene Sulfonate‐Protein System

Abstract

It was found that the fluorescence intensity of lanthanum (III) (La³⁺)‐quercetin (Qu) complex is greatly enhanced by proteins in the presence of sodium dodecyl benzene sulfonate (SDBS). Based on this finding, a new fluorimetric method for the determination of proteins was developed. Under optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of proteins in the range of 2.5×10^?8 to 1.0×10^?5 g/mL for bovine serum albumin (BSA), 5.0×10^?8 to 1.5×10^?5 g/mL for human serum albumin (HSA), and 1.0×10^?7 to 1.5×10^?5 g/mL for egg albumin (EA). Their detection limits (S/N=3) are 5.0×10^?9 g/mL, 7.0×10^?9 g/mL, and 2.1×10^?8 g/mL, respectively. The interaction mechanism was also studied.