High-Performance Liquid Chromatographic Determination of Quinolizidine Alkaloids in Radix Sophora Flavescens Using Tris(2,2′-Bipyridyl)Ruthenium(II) Electrochemiluminescence

Electrogenerated chemiluminescences (ECLs) of quinolizidine alkaloids including matrine (MT), sophocarpine (SC), and sophoridine (SRI) are studied. The light emission is caused by an electro-oxidation reaction between Ru(bpy)₃²⁺ and the tertiary amino group on the alkaloid compounds. A thin-layer flow cell equipped with a glassy carbon disk electrode (22.1mm²) at the potential of ⁺1.30V (vs. Ag/AgCl) was applied for ECL observation. MT, SC and SRI were separated and quantitatively determined within 25min by an ODS-80 Ts reversed-phase column with a mobile phase containing 80mmolL^–1 NaH₂PO₄–K₂HPO₄ buffer+acetonitrile (7:3)+40mmolL^–1 sodium dodecyl sulfate (pH 6.5). The determination limit at an S/N of 3 ranged from 3×10^–9gmL^–1 for MT, 6×10^–9gmL^–1 for SC and 1×10^–9gmL^–1 for SRI. The recoveries are from 92 to 108%, with repeatability ranging from 1.3 to 4.5% (relative standard deviation). The method was successfully applied to the determination of quinolizidine alkaloids in Sophora flavescens samples.     

Flow-Injection Chemiluminescent Determination of Piroxicam Using Tris (2,2′-bipyridyl) Ruthenium(II)—Potassium Permanganate System

Abstract

A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of an analgesic agent drug, piroxicam. The method is based on the chemiluminescence reaction of piroxicam with an acidic potassium permanganate and Ru(bipy)₃ ²⁺. The chemiluminescence intensity is greatly enhanced when quinine sulfate is used as a sensitizer. After optimization of the different experimental parameters, a calibration graph was obtained over a concentration range of 3.0 × 0^?8–3.0 × 0^?5 mol L^?1 with the detection limit of 1.0 × 0^?8 mol L^?1. The relative standard deviation is 1.5% (n = 11) for the determination of 8.0 × 10^?7 mol L^?1 piroxicam. The proposed method was successfully applied to commercial tablets, spiked serum, and urine samples.     

Spectrophotometric Simultaneous Determination of Zinc(II), Manganese(II) and Iron(II) in Pharmaceutical Preparations Using OSC-PLS

The purpose of this paper is to develop a fast and sensitive spectrophotometric method for the simultaneous determination of zinc(II), manganese(II) and iron(II) in pharmaceutical preparations. The method presented in this work is based on the well-known reaction of these ions with 4-(pyridylazo)resorcinol (PAR)1. The application of quantitative chemometric methods, particularly PLS to multivariate chemical data is becoming more widespread owing to the availability of digitized spectroscop…     

The Facile Oxidation of Thiols to Disulfides with Bis(2,2′-Bipyridyl) Copper-(II) Permanganate

The title compound is used in the oxidation of several thiols to produce their corresponding disulfides in excellent yields in methylene chloride at room temperature.     

Spectrophotometric-Complexometric Titrations(Ⅲ)——The Titration of Micro-quantities of Titanium (Using Benzilic Acid as Masking Agent)

When DCTA is used as the titrant,benzilic acid is a specific masking agent for Ti (IV).Using the DCTA-benzilic acid masicing method and spectrophotometric end point,90 ppb of Ti can be [selectively titrated.Micro-quantities of Ti in quartz samples can be accurately titrated without prior seperation.We have found that malonic acid is a specific masking agent for Al.When it is used simultaneously with benzilic acid,Ti and Al or Ti,Al and Fe (II) can be titrated stepwise.     

2,4′-Bipyridyl complexes with cobalt(II) and nickel(II)

Summary Complexes of empirical formulae [ML₂Cl₂(OH₂)₂], [CoL₂Br₂(OH₂)₂]L·4H₂O, [NiL₂Br₂(OH₂)₂]L₂·2H₂O, [ML₂(OH₂)₄]L₂(NO₃)₂ and [ML₄(OH₂)₂](ClO₄)₂·2H₂O (M = Co^II, Ni^II, L = 2,4-bipyridyl) were synthesized and characterized by elemental and spectral analyses. The thermal decomposition of the complexes was also investigated.Author to whom all correspondence should be directed.     

Spectrophotometric Determination of Palladium (11) With 2,2′-pyridilmonoxime

Abstract

A visible spectrophotometric method is described for the determination of palladium with 2,2′-pyridilmonoxime. The effects due to pH, time, solvents, reagent concentration and diverse ions are reported. Reasonable structures for the reagent and palladium chelate based on analysis and infrared evidence are proposed.     

Photochemical Behavior of Platinum(II) and Palladium(II) Complexes of 4,4′-Dimethyl-2,2′-Bipyridine

Several mixed-ligand complexes of formula [MX 2 (MBPY)] {where M is Pd(II) or Pt(II); X is Cl m , I m , N 3 m or NO 2 m and MBPY is 4,4'-dimethyl-2,2'-bipyridine} have been prepared. The UV-Vis spectra of these complexes were found to show a low-lying MLCT band and on irradiation at the MLCT band these complexes sensitize the oxidation of 2,2,6,6-tetramethyl-4-piperidinol (XH) in N , N -dimethylformamide (DMF) to 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinoloxy free radical (XO). This photo-oxidation reaction involves singlet molecular oxygen ( 1 O 2 ) as an intermediate and its presence was confirmed by quenching studies using bis(diethyldithiocarbamato)nickel(II) [Ni(DDTC) 2 ], a well-known 1 O 2 quencher. The ability of the complexes to photosensitize the above photo-oxidation reaction follows the order: [Pt ( N 3 ) 2 ( MBPY ) ] ( 2 ) ～ [Pt ( NO 2 ) 2 ( MBPY ) ] ( 3 ) > [PtCl 2 ( MBPY ) ] ( 4 ) > [PtI 2 ( MBPY ) ] ( 1 ) > [Pd ( NO 2 ) 2 ( MBPY ) ] ( 7 ) ～ [Pd ( N 3 ) 2 ( MBPY ) ] ( 6 ) > [PdCl 2 ( MBPY ) ] ( 8 ) > [PdI 2 ( MBPY ) ] ( 5 ), which reflects the nature of the metal ion and the nature of the ligands present in the complexes.     

Investigation of complexes of zinc(II) and cadmium(II)DI-n-butyldithiocarbamates with 2,2′-bipyridyl

A new mixed-ligand complex, Cd(S₂CN(C₄H₉)_{2 2})₂(2,2′-Bipy), was synthesized. A polycrystal X-ray diffraction analysis was performed (DRON-3M and DRON-UM1 diffractometers, CuK_α radiation, Ni filter) and the crystal structure was determined [Enraf-Nonius CAD-4 automatic diffractometer, MoK_α radiation, 2440 nonzero independent reflections, 153 refined structural parameters, R is 0.11 for I>2σ(I)]. Crystal data for C₂₈H₄₄CdN₄S₄ : a = 28.716(4), b = 6.848(6), c = 17.188(2) Å, space group Pcca, V-3380.2(7) ų, Z = 4, M = 679.42, dcaU.= 1.335 g/cm3. The structure consists of monomeric molecules in which the cadmium atom has a distorted octahedral environment. The polycrystal diffraction analysis revealed that the complex is isostructural with the defined complex Zn(S₂CN(C₄Hg)₂)₂(2,2′-Bipy). A crystal-chemical search on metal dialkyldithiocarbamates in the Cambridge Structural Database was accomplished and isostructural pairs of Zn and Cd metal complexes were found.     

Electrochemistry of microparticles of tris (2,2′-bipyridine) ruthenium(II) hexafluorophosphate

The electrochemical behaviour of tris(2,2′-bipyridine)ruthenium(II) hexafluorophosphate (Ru(II)) microparticles, immobilised on a graphite electrode and adjacent to an aqueous electrolyte solution, has been studied by cyclic voltammetry and an in situ spectroelectrochemical technique. The solid Ru(II) complex exhibits one reversible redox couple with a formal potential (E_f) of 1.1 V versus Ag¦AgCl. The continuous cyclic voltammetric experiments showed that the Ru(II) microparticles are stable during the electrochemical conversions. The in situ spectroelectrochemical study showed that the absorbance at 463 nm decreased due to the oxidation of Ru(II) to Ru(III). Upon reduction, the growth of absorbance at 463 nm was observed due to the formation of Ru(II) complex and this process was reversible.     

2,4′-Bipyridyl complexes with silver(I) and copper(II)

Summary Ag^I and Cu^II complexes with 2,4-bipyridyl (2,4-bipy or L) with the general formulae AgL₂X (where X = NO _inf3 ^sup– or ClO₄ ^-), CuL₂X₂·2H₂O (X = Cl^- or Br^-), CuL₄SO₄·4H₂O, CuL₄(NO₃)₂·2H₂O and CuL₄(ClO₄)₂·H₂O have been isolated pure and characterized by analytical, spectral and magnetic measurements. The thermal decomposition of these complexes was studied under non-isothermal conditions in air.     

A cyclometallated analogue of tris(2,2′-bipyridine)ruthenium(II)

A cyclometallated analogue of the well-known tris(2,2′-bipyridine)ruthenium(II) cation has been prepared from 2-phenylpyridine. The bis(2,2′-bipyridine)(2-phenylpyridine-C,N)ruthenium(II) cation is readily prepared from [Ru(bipy)₂Cl₂] and 2-phenylpyridine in the presence of silver(I); the spectroscopic and electrochemical properties of this species are compared with those of [Ru(bipy)₃]²⁺.     

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.     

Bis(2,2′bipyridine) ruthenium(II) complexes

A reinvestigation of the photolysis of [Ru(bipy)₃](NCSe)₂ in ethanol under dinitrogen has failed to give the previously reported [Ru(N₃)₂bipy₂] but, under appropriate conditions, may yield the complex [Ru(NCO)₂bipy₂].     

Substituted 2,2′-azoquinoxaline palladium(II) complexes

2,2′-Azobis(5,6-dimethylquinoxaline) was prepared by reacting 5,6-dimethylquinoxalinone-2(1 H)-one oxime with CoCl₂. Binuclear cyclopalladated azoquinoxaline complexes were prepared from the corresponding quinoxalin-2(1 H)-one oxime and Pd(OAc)₂. This revised version was published online in June 2006 with corrections to the Cover Date.     

Application of Polymer-Embedded Tris(2,2′ Bipyridine-Ruthenium(II) to Photodetection of Oxygen

A Nafion film containing tris(2,2′-bipyridine)ruthenium(II) as a luminescence probe was applied to photodetection of oxygen in a gas by utilizing the luminescence quenching by dioxygen. The linear Stern-Volmer plots of the emission intensity with respect to the oxygen concentration allowed quantitative determination of the oxygen. From the emission decay studied by a single-photon counting method, it was concluded that the quenching of the excited state Ru complex by oxygen proceeds by a conventional dynamic mechanism.     

Tris(2,2′-bipyridyl)ruthenium(II) electrochemiluminescent determination of ethyl formate

Analytical and Bioanalytical Chemistry - Ethyl formate is extensively used as food flavor, fungicide, and larvicide. It naturally exists in coffee, fruits, honey, brandy, and rum as well as dust...     

Complexes of Te(IV), Te(II) and Se(II) with 2,2′-iminodiethanoldithiocarbamate

Novel complexes of 2,2′-iminodiethanoldithiocarbamate (DEADTC⁻) with Te(IV), Te(II) and Se(II) having the composition Te(DEADTC)₄, Te(DEADTC)₂I₂, Te(DEADTC)₃I, Te(DEADTC)₂ and Se(DEADTC)₂ were isolated and characterised by X-ray, magnetic, spectral (UV, IR) and conductance and molecular weight measurements. 2,2′-Iminodiethanoldithiocarbamate is shown to be weaker in its ligation behaviour than diethyldithiocarbamate.