Liquid Chromatographic Analysis of Plasma Melphalan with Amperometric Detection in a Patient with Breast Cancer

Abstract

We developed a liquid chromatographic method for the measurement of melphalan in plasma and studied a patient with breast cancer, given melphalan before an Autologous Bone Marrow Transplant (ABMT). A reverse phase C 18 column with isocratic elution and amperometric detection was used. The potential was set at + 0.95V. Sample pretreatment involved extraction of the drug with ethyl acetateethanol. The method is sensitive and precise and was used to study the pharmacokinetics of melphalan.     

Determination of Zearalenol and Zearalenone Using Electrochemical Detection

Abstract

A method is described for the determination of zearalenol and zearalenone in corn using electrochemical detection. the sample is extracted with chloroform, and the extract is cleaned up by liquid-liquid partition. Zearalenol and zearalenone are resolved by liquid chromatography (LC), using a C₁₈ column and a mobile phase consisting of 35 + 25 + 40 CH₃ CN + MeOH + H₂O and 0.02 mole/L sodium acetate buffered at pH 6.5. Zearalenol and zearalenone were detected with an electrochemical detector at an applied potential of +0.95V vs Ag/AgCl. Average recoveries of zearalenol and zearalenone in corn samples spiked at levels of 25–1000 ng/g were 104,2 and 97.5%, respectively. the coefficients of variation for the proposed method were 10.8% for zearalenol and 8.8% for zearalenone.     

Electrochemical Behavior of Dopamine at a Mercury Electrode in the Presence of Citrate: Analytical Applications

Abstract

Dopamine can be determined by voltammetric methods using a mercury electrode, previously oxidized at +0.30 V. The oxidation product formed is stabilized in the presence of citrate and undergoes reduction at ?0.31 V. This work describes the electrochemical behavior of dopamine at a mercury electrode in the presence of citrate and its application in the development of a square‐wave voltammetric method for the dopamine determination in pharmaceutical formulations. The method was in‐house validated for determination of dopamine in injectable formulations. The detectability of the method was 0.02 µg ml^?1.     

Determination of Dimethoate in Human Blood by Impregnated Silica Plates and Gas Chromatography

Abstract

A method for the determination of Dimethoate in human blood is presented here. After extraction with acetone-hexane (1+9V/V) dimethoate is separated on p-cresol impregnated thin silica plates as well as by Gas Chromatography using nitrogen phosphorous detector. The recovery of dimethoate added to human blood was quite satisfactory.     

Catalytic Kinetic Determination of Trace Amounts of Iron(III) With Polarographic Detection

Abstract

This method is based on the catalytic effect of Fe³⁺ on the oxidation reaction between Acid Chrome Blue K and potassium bromate in sulfuric acid medium at 100deg;C, and in 0.08 mol/L NH₄OH - 0.01 mol/L (NH₄)₂ SO₄ supporting electrolyte, Acid Chrome Blue K exhibits a sensitive polarographic wave at -0.55V vs. SCE, and change of concentration is traced by a polarographic detection technique. The linear range of Fe³⁺ is 10–100ng/mL. This new catalytic method has been applied to the determination of iron in natural water and food with satisfactory results.     

PREPARATION OF NEW CHLORAMBUCIL ANALOGS BY BIS-SRN1 METHODOLOGY

ABSTRACT

Three series of chlorambucil analogs were prepared by an original reaction of 1-(3-chloro-2-chloromethylpropenyl)-4-nitrobenzene with various nitronate anions under electron transfer reaction conditions.     

Adsorptive Stripping Voltammetric Determination of Albendazole at a Hanging Mercury Drop Electrode

ABSTRACT

Albendazole is determined by differential-pulse adsorptive cathodic stripping voltammetry at a hanging mercury drop electrode using the reduction peak of its copper(II) complex at ?0.28V at an accumulation potential 0.0V vs. Ag/AgCl electrode. The optimum conditions of pH, accumulation potential and accumulation time were studied. The calibration graph for the determination of albendazole was linear in the range 3.0X10^?8 - 9X10^?7M with a relative standard deviation of 2.8%. The detection limit was 1.0X10^?8M after 180s accumulation at 0.0V. The effect of common excipients and metal ions on the peak height of albendazole was studied. The presence of Cu²⁺ ions forms a stable complex with albendazole which is strongly adsorbed at the mercury electrode surface. The method was applied to the determination of the drug in commercially available dosage forms.     

Poly[Ni(II)Protoporphyrin IX] Modified Electrode for Amperometric Detection of Acetylcholine (Ach) and Choline (Ch)

Abstract

Poly[Ni(II)Protoporphyrin IX] (pNiPP) modified electrode can be used as an alternative method for direct amperometric detection of Acetylcholine (Ach) and Choline (Ch). This response is highly dependent on the electrode potential, that must be higher than +0.4 V versus Ag/AgCl with a maximum at +0.6 V.

Other amino derivatives such as ethanolamine and tetrabutyl ammonium hydroxide did not show amperometric response in the same experimental conditions. On the contrary, KCl shows an increasing amperometric signal in flow injection for a concentration range of 10^?3 to 1 M, indicating certain sensitivity of membrane to Cl^? ions. The lowest detection limit corresponds to the highest cationic volume. The response for acetylcholine is slightly higher than for choline and is almost completely non‐linear for both substrates. The proposed model for the response is Y=(A×X)/(B+X) according to AICc Akaike method.

Choline, in a complex solution, was analyzed by HPLC with the chemically modified electrode as detector.     

过渡金属与新型硝基酚臂式氮杂18-冠-6配位性能的研究

合成并表征了1,10-二氧-4,7,13,16-四氮杂18-冠-6 (1)母体及其四取代硝基酚臂式衍生物 (2)。在H₂O-DMSO(V/V=1/4)混合溶剂中用UV-Vis光谱法对冠醚2与H⁺、Mn²⁺、Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Cd²⁺和Hg^{2+相似文献}   

Method for Determination of Codeine and Morphine in Rat Whole Blood by High Pressure Liquid Chromatography

Abstract

A HPLC method to simultaneously determine codeine and morphine in rat whole blood has been developed and evaluated. This method is based on a selective extraction and reversed-phase chromatography which results in chromatograms with 220 to 3500 theoretical plates for morphine and codeine. Detection is by electrochemical oxidation at +1.2V vs Ag/AgCl. In this method, the procedure of blood centrifugation for plasma preparation is eliminated. Therefore, the blood volume required is decreased and the sensitivity of analysis is considerably increased. Concentrations of codeine and morphine are low as 2ng/ml can be quantitated in as little as 100 mcl of rat whole blood.     

Indication Ion Square Wave Voltammetric Determination of Thiamine and Ascorbic Acid

Abstract

Cd²⁺ ion was used as an electrochemical indicator to detect V_B1 or Vc using square ware voltammetry (SWV) at a mercury film‐coated glassy carbon (GC) electrode. At pH=10 NH₃‐NH₄Cl buffer, a new cathodic peak was found at ?0.360 V (vs.SCE) by addition of thiamine, and the peak current of SWV was linear with the concentration of thiamine in the range of 1×10^?6 to 4×10^?3 M. On the other hand, the SWV peak current of Cd²⁺ at ?0.856 V linearly decreased with addition of ascorbic acid in the range of 6×10^?6～10^?3 M. The effects of interference, such as citric acid, DL‐malic acid, and calcium panlothenate, on thiamine or ascorbic acid determination were investigated. This method was successfully applied to the determination of thiamine or in pharmaceutical preparation.     

Preparation of a fluorescent sensor based on BODIPY-functionalized hydroxyapatite nanoparticles and spectroscopic study of the Cd2+ and Zn2+ complex formation

A new fluorescent chemosensor 1, which based on hydroxyapatite (HA) nanoparticles covalently functionalized with a difluoroboron dipyrromethene, has been prepared by nucleophilic substitution of the fluorescent dye 3-chloro-4,4-difluoro-8-(4-tolyl)-5-[bis(pyridine2-ylmethyl)amino]-4-bora-3a,4a-diaza-s-indacene (2) with surface-modified HA nanoparticles. The HA particles were prepared by using SiO₂ as templates (THA) with 3-(aminopropyl)triethoxysilane (THA-APTES). Substitution of the electron-withdrawing chlorine in 2 by an electron-donating amino group of HA changes the properties of the nanoparticles 1 and the corresponding fluorescent dye 2. Absorption and emission maxima of 1 in ethanol are red-shifted by 75 and 30?nm, respectively, in comparison with those of 2. In contrast to no selectivity of dye 2 for Cd²⁺ or Zn²⁺ in EtOH/H₂O (95/5?V/V) solutions, the nanofluorescent probe 1 forms 1?:?1 complexes with Cd²⁺ or Zn²⁺, producing an instant color change along with large hypsochromic shifts in the absorption and fluorescence spectra by 70 and 35?nm, respectively, and large cation-induced fluorescence amplifications.     

Synthesis, crystal structure, and spectra of 9(E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone and its cation-anion complex with copper(I) bromide

The reaction of 1-hydrazino-3,3-dimethyl-3,4-dihydroisoquinoline with 9,10-phenanthrenequinone gave (9E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone (L). The reaction of L with copper(II) bromide gave the complex (LH)[CuBr₂]. The crystal structures of the monohydrate L · H₂O (I) and the isolated complex (LH)[CuBr₂] (II) were determined by X-ray diffraction. The structural units of I are pseudo-centrosymmetric dimers in which the L and water molecules are combined by strong hydrogen bonds. The active H atom is located at the N(1) atom of the isoquinoline fragment of the L molecule. The L molecule occurs in the crystal as the cis, trans isomer with respect to exocyclic C=N bonds at the isoquinoline and phenanthrenequinone fragments, respectively. Complex II has a cation-anion structure. The LH⁺ cation as the cis, cis isomer is protonated at N(2) and stabilized by two intramolecular hydrogen bonds. In the CuBr₂⁻ anion, the copper atom in the oxidation state +1 has a linear coordination, the C-Br bond length is 2.185(4) ± 0.005 ?, and the BrCuBr angle is 179.8(4)°. The main ion-ion interactions in structure II are shortened contacts involving bromine atoms, which combine cations and anions into a three-dimensional framework. Original Russian Text ? V.V. Davydov, V.I. Sokol, N.V. Rychagina, R.V. Linko, M.A. Ryabov, Yu.V. Shklyaev, V.S. Sergienko, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 6, pp. 958–970.     

Analytical aspects of some organic acids

Summary A direct titrimetric method for the estimation of iron(III) has been developed, which involves the adjustment of concentration of iron(III) andPh, dilution, addition of 1 ml of 2% indicator solution and titration with EDTA (30° to 35° C). It is based on the fact that the iron(III) forms a blue coloured complex which is destroyed at the 11 molar ratio making the end-point of the titration. Quantity of iron(III) as small as 23.2 mg can be titrated accurately when present in a volume of 100 ml. Study of interferences revealed that quite a number of elements like Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, UO₂ ²⁺ and Mn²⁺ does not interfere, whereas much interference is caused by Cu²⁺, Zn²⁺, Pb²⁺, Fe²⁺, Co²⁺, Ni²⁺, ZrO²⁺, V0²⁺, Al³⁺, Cr³⁺, Ti⁴⁺, Ce⁴⁺ and Th⁴⁺. The method proposed for iron(III) is selective and should be of considerable use in many cases.Part III: See Z. analyt. Chem. 167, 332 (1959).     

Determination of Physostigmine in Plasma by Liquid Chromatography with Dual Electrode Amperometric Detection

Abstract

Physostigmine in plasma is determined after solid phase extraction. Ion-pair liquid chromatography is used for the separation and dual electrodes in a series mode are used for the detection. Physostigmine is first oxidized at +1.0 V and the reaction product formed is determined by reduction at +0.10 V versus Ag/AgCl. The solid phase extraction gives a recovery of 62 ± 6% (n=5) from plasma spiked with physostigmine to a concentration of 14 ng/mL. A detection limit of 0.5 ng/mL is obtained from a sample of 2 mL plasma.     

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.     

Selective Determination of Verapamil in Pharmaceutics and Urine Using a Boron‐doped Diamond Electrode Coupled to Flow Injection Analysis with Multiple‐pulse Amperometric Detection

This work presents a simple and low‐cost method for fast and selective determination of Verapamil (VP) in tablets and human urine samples using a boron‐doped diamond working electrode (BDD) coupled to a flow injection analysis system with multiple pulse amperometric detection (FIA‐MPA). The electrochemical behaviour of VP in 0.1 mol L⁻¹ sulfuric acid showed three merged oxidation peaks at around +1.4 V and upon reverse scan, one reduction peak at 0.0 V (vs. Ag/AgCl). The MPA detection was performed applying a sequence of three potential pulses on BDD electrode: (1) at +1.6 V for VP oxidation, (2) at +0.2 V for reduction of the oxidized product and (3) at +0.1 V for cleaning of the working electrode surface. The FIA system was optimized with injection volume of 150 μL and flow rate of 3.5 mL min⁻¹. The method showed a linear range from 0.8 to 40.0 μmol L⁻¹ (R>0.99) with a low limit of detection of 0.16 μmol L⁻¹, good repeatability (RSD<2.2 %; n=10) and sample throughput (45 h⁻¹). Selective determination of VP in urine was performed at+0.2 V due to absence of interference from ascorbic and uric acids in this potential. The addition‐recovery tests in both samples were close to 100 % and the results were similar to an official method.     

A novel turn-on fluorescent probe for Hg2+ detection based on rhodamine B spirolactam derivative

ABSTRACT

In this work, a new turn-on fluorescent probe 1 for Hg²⁺ ions detection based on rhodamine B spirolactam was reported. Among tested metal ions, probe 1 shows high selectivity towards Hg²⁺ in the the mixture solution of methanol and 0.02 M HEPES buffer (V/V = 9:1, pH = 7.2). No absorption and emission band of probe 1 was observed in the range from 450 to 700 nm. While only addition of Hg²⁺ to probe 1 could lead to appearance of a new absorption band centered at 553 nm and a fluorescence emission band around 577 nm upon excitation at 520 nm. Moreover, it exhibits excellent linear relationship (R² = 0.9993) between fluorescence intensity at 577 nm and the concentration of Hg²⁺ from 1.6 to 32 μM. The sensing mechanism was proven to be spirolactam ring open induced by Hg²⁺ through ¹H NMR, MS, absorption and fluorescence spectra. In addition, probe 1 could detect Hg²⁺ in real water samples and on filter paper, which demonstrates its application in environment science.