Flow—injection Chemiluminescence Determination of Reserpine in Medicine and Biological Fluids with Controlled—Reagent—Release Technology

A sensitive and rapid chemiluminescence(CL) flow injection with controlled-reagent-release technology for the determination of reserpine was proposed.The Cl reagents,luminol and dichromate,uses in this sensor,were all immobilized on anion-exchange resin.Through injection of 100μl of water,the reagents on the anion-ex-change resin column were eluted and in the presence of reserpine ,the CL intensity was decreased,by which reserpine could be sensed.Reserpine was quantified by measuring the decrement of CL intensity,which was observed linear with the logrithm of reserpine concentration in the rage of 1.0-500.0ng/mL,and the limit of detection was 0.4ng/mL(3σ)with a relative standard deviation of less than 3.0?The proposed procedure was applied in the assay of reserpine in pharmaceutical preparation and biological fhuids without any pre-treatment process and with sampling frequencies of 72 times per hour.     

Determination of levodopa in pharmaceutical preparations by irreversible biamperometry

Based on the electrocatalytic oxidation of levodopa at gold electrode and the reduction of permanganate at platinum electrode, a novel flow injection irreversible biamperometric method is developed for the determination of levodopa under the potential difference of 0 V imposed between two electrodes. In H2SO4 solution, the linear relationships between currents and the concentrations of levodopa are obtained in the range from 0.04 mg/L to 20 mg/L with the detection limit of 0.012 mg/L. The proposed method is applied to the determination of levodopa in pharmaceutical preparations.     

Determination of sulfite in water samples by flow injection analysis with fluorescence detection

<正>A fast,sensitive,and reliable method for the determination of sulfite(SO_3~(2-)) in fresh water and seawater samples was developed.The proposed method was based on the reaction of o-phthalaldehyde(OPA)-sulfite-NH_3 in alkaline solution,with flow injection analysis and fluorescence detection.The experimental parameters were investigated in pure water and seawater matrixes. The detection limits(S/N = 3) were 0.006μmol/L in pure water and 0.018μmol/L in seawater for SO_3~(2-).The method was successfully applied to analyze SO_3~(2-) in the samples of rain water and flue gas desulfurization seawater.     

ClO3--SO32--Rh6G-SDBS体系的化学发光及其用于亚硫酸根测定

Based on the micelle synergism mechanism, a chemiluminescence （CL） flow system for the determination of sulfite was described. The CL signal generated from the reaction of chlorate with sulfite in acidic solution was very weak, while the interfusion of sodium dodecylbenzenesulfonate （SDBS） resulted in a highly chemiluminescent intensity. The major goal of this work was to investigate and develop the SDBS rnicelle synergetic CL system. The mechanism was proposed and proved by spectrometry. The results indicated that the unique structure of SDBS micelles prorooted the aggregation of rhodamine 6G （Rh6G） and a much easier energy transfer, leading to a marked shift to red in the CL emission. This CL system was developed for the determination of sulfite and the concentration of sulfite was proportional to the CL intensity in the range of 5.0× 10^-8--1.0× 10^-5 mol/L with the detection limit of 1.7×10^-8 mol/L （S/N=3）. The relative standard deviation was 3.3% for 1.0×10^ 6 mol/L sulfite solution with eleven repeated measurements. This method was successfully applied to the determination of sulfite in powder sugar.     

Determination of catecholamines by ion chromatography coupled to acidic potassium permanganate chemiluminescence detection

A simple,fast,sensitive,highly selective and eco-friendly analytical method for the determination of catecholamines in human urine by ion chromatography（IC） with chemiluminescence（CL） detection was described in this paper.Using 12 mmol/L H₂SO₄ without any organic additive as eluent,three catecholamines including epinephrine（EP）,norepinephrine（NE） and dopamine（DA） were well separated on a cation-exchange column.The CL detection was based on the reaction of analytes with acidic potassium permanganate in the presence of formaldehyde as an enhancer.The absence of methanol and acetonitrile in eluent made the proposed method more sensitive and eco-friendly.Under the optimal conditions,the linear range of the proposed method was in the range of 0.02-0.5μg/mL.The limit of detection（LOD） was in the range of 0.6 and 5.1μg/L.The relative standard deviations （RSD） for 0.1μg/mL mixed standard solution were in the range of 0.8-1.9%（n = 11）.The method has been applied to the determination of catecholamines in human urine successfully.Excellent spiked recoveries were achieved for catecholamines ranged from 91.2%to 112.7%.     

First-order Derivative Spectrophotometry for the Determination of Vitamin C in Medicament

A novel method for the determination of vitamin C（Vc） is proposed in this article. After the reaction with Folin-Ciocalteau reagent at ambient temperature, Vc solution was scanned at 750--1100 nm, and its first-order derivative spectrum were obtained from the original spectrum. The values of derivative selected at 995 nm were used for determination. It was proved that Vc could quickly react with Folin-Ciocalteau reagent within 5 min and the product was quite stable for a long time. The conditions required for this method is not very complicated, its precision and accuracy are similar to those of the iodometric titration described in Chinese Pharmacopoeia, and the limit of detection is 0.312 μg/mL. The determination of the results of vitamin C tablet, pill, and injection demonstrates that this method has wide pharmaceutical applications.     

Indirect Flow Injection Chemiluminescence Method for the Determination of Tetracycfines Using Cu（]I） as a Probe Ion

This paper reported an indirect flow injection chemiluminescence （FI-CL） method for the determination of the drugs tetracycline （TC）, chlortetracycline （CTC） and oxytetracycline（OTC） using Cu（ Ⅱ ） as a probe ion. The CL reaction was induced on-line and after injection of the sample the negative peaks appeared as a result of complexation. The method was applied to the determination of TCs in pharmaceuticals and human urine with recoveries in the range95-105%.     

Flow-injection Determination of Cysteine,N-Acetyl Cysteine and Glutathione in Pharmaceuticals via Potassium Ferricyanide-Fe(Ⅲ) Spectrophotometric System

A simple flow injection spectrophotometric method is reported for the determination of cysteine,N-acetyl cysteine and glutathione based on the reduction of Fe(Ⅲ)/ferricyanide,the in situ reduced ions are reacted with unreduced portion of ferricyanide/Fe(Ⅲ) to form soluble Prussian blue,which is monitored at 735 nm.The calibration graphs are linear in the concentration ranges of(1―100)×10-6 mol/L for cysteine and N-acetyl cysteine,and(1―50)×10-6 mol/L for glutathione.The relative standard deviations of 1.8%,2.5% and 1.9% were found for eleven replicate analyses of 5×10-6 mol/L cysteine,N-acetyl cysteine and glutathione.The limits of detection(3σ blank) at 5×10-7 mol/L for cysteine,and 3×10-7 mol/L for N-acetyl cysteine and glutathione were obtained.The proposed method allowed 60 injections/h.The effects of common substances present in pharmaceuticals and human physiological fluids were examined.The method was applied to determining cysteine in pharmaceutical formulations with the recoveries in a range of 97% to 106% and the results obtained are agreed well with labeled values.     

Analysis of Vitamin K3 by a Fluorescent Spectroelectrochemistry Method

A simple and sensitive spectroelectrochemistry method for the determination of vitamin K 3 was developed by combining electrolysis and fluoremetry. This method was based on that vitamin K 3 was reduced at a glassy carbon electrode, and its product with characteristic fluorescence at 420 nm was determined with excitation wavelength at 309 nm. Under optimized electrochemical reaction conditions and fluorescent experiment parameters, the fluores-cence intensity was proportional to the concentration of vitamin K 3 in a range from 3.50×10 ?7 to 1.05×10 ?5 mol/L with a correlation coefficient of 0.9991, and detection limit was estimated to be 7.50×10 ?8 mol/L at a signal/noise ra-tio of 3. The relative standard deviation was less than 4.3%(n=5) and the recovery was in a range of 97%―105% for the determination of vitamin K 3 in pharmaceutical preparations. The result is satisfactory for the determination of vi-tamin K 3 as comparison to that from HPLC method.     

Study on the interference elimination of trace cadmium in superalloy by ICP-MS / MSEI北大核心CSCD

A triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS / MS) method was developed for the determination of trace Cd in superalloys. Meanwhile, the interference elimination effects of different collision / reaction gases (He, O2 and NH3) in single quadrupole mode (SQ) and double quadrupole mode (QQQ) were investigated. The results indicated that the modes of QQQ-O2 and QQQ-NH3 possessed satisfactory interference elimination effect than the others. The optimal flow rates of O2 and NH3 were 0. 75 mL / min and 0. 50 mL / min, respectively. In order to verify the interference elimination effect, the recovery rate of 0. 1 μg / g Cd in 0. 10 mg / g to 100 mg / g Mo content solutions, as well as the determination results of superalloy standard substance and the actual sample were investigated. The measured value was within the range of the standard value, and the measured value of the actual sample was consistent with that of the hydride generation atomic fluorescence method. Therefore, the proposed method can eliminate the polyatomic ions interference of Mo on trace Cd. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Simultaneous kinetic spectrophotometric determination of norfloxacin and rifampicin in pharmaceutical formulation and human urine samples by use of chemometrics approaches

A kinetic spectrophotometric method with aid of chemometrics is proposed for the simultaneous determination of norfloxacin and rifampicin in mixtures. The proposed method was applied for the simultaneous determination of these two compounds in pharmaceutical formulation and human urine samples,and the results obtained are similar to those obtained by high performance liquid chromatography.     

KINETIC AND APPLICATION: STUDIES ON THE REACTION SYSTEM OF OSMIUM(Ⅳ)-ARSENIC(Ⅲ)-CHLORATE

The experiments have proved that Os(Ⅳ) has very strong catalytic effect on the chlorate oxidation of As(Ⅲ) in perchloric acid media, and As(Ⅲ) exhibits a sensitive single-sweep oscillopolarographic wave at-0.75 V vs. SCE. The kinetics of this catalytic reaction has been investigated by the initial rate procedure. The mechanism has been proposed. A new and highly sensitive catalytic reaction-oscillopolarographic method for the determination of ultratrace amounts of osmium has been described, based on the Os(Ⅳ) catalytic effect on the reaction. The linear range of 5.0×10~(-11)-4.4×10~(-9) mol/L and 6.0×10~(-9)-1.3×10~(-7) mol/L Os was obtained using the fixed-time procedure and the initial rate procedure, respectively. Osmium in refined ore was analysed by this method.     

Osteryoung square wave voltammetric determination of lactose in food samples by a derivative procedure

A method for determination of lactose in food samples by Osteryoung square wave voltammetry （OSWV） was developed. It was based on the nucleophilic addition reaction between lactose and aqua ammonia. The carbonyl group of lactose can be changed into imido group, and this increases the electrochemical activity in reduction and the sensitivity. The optimal condition for the nucleophilic addition reaction was investigated and it was found that in NH4C1-NH3 buffer of pH 10.1, the linear range between the peak current and the concentration of lactose was 0.6-8.4 mg L-l, and the detection limits was 0.44 mg L- 1. The proposed method was applied to the ＇determination of lactose in food samples and satisfactory results were obtained.     

A Study on the Interaction of the DAS-K with Bovine Serum Albumin by On-line Ultrafiltration and Chemiluminescence

Potassium dehydroandrographolide succinate （DAS-K） has antibacterial and antiviral effects. It has been used widely for the treatment of virus pneumonia, malaria and respiratory infections. In this work, a novel flow-injection chemiluminescence （CL） method for the determination of DAS-K was proposed. The method is based on the reaction between DAS-K and hexacyanoferrate（III） in alkaline solution to give weak CL signal, which is enhanced by rhodamine B. The experimental conditions for the CL reaction were optimized and the possible reaction mechanism was discussed. Under the optimum conditions, the concentration of DAS-K is proportional to the CL intensity in the range of 0.1-80 μmol·L^-1 with a detection limit of 0.05 μmol·L^-1. The interaction of the DAS-K with bovine serum albumin by on-line ultrafiltration and flow-injection chemiluminescence was studied. The concentrations of unbound DAS-K from ultra filter tube were determined by the flow-injection CL method. The binding parameters were estimated by the Scatchard plot and Klotz plot. The proposed system proved that FIA-CL coupled with on-line ultrafiltration sampling was a fast and simple technique for the study of drug-protein interaction.     

Fabrication of the electrochemically reduced graphene oxide-bismuth nanoparticles composite and its analytical application for an anticancer drug gemcitabine

The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite(ErGOBi) as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride(GMB). The Er-GOBi interface was prepared by drop casting of bismuth nitrate-graphene oxide suspension on a glassy carbon electrode(GCE) followed by electro-reduction in the potential range of 0.6 V to 1.7 V. SEM, FTIR, EDAX and AFM techniques were employed for the characterization of prepared materials. Cyclic voltammetric and electrochemical impedance spectroscopic methods were used to understand the charge transfer properties of stepwise modification of Er-GOBi/GCE. GMB exhibited an irreversible oxidation peak at 1.144 V on Er-GOBi/GCE in phosphate buffer of p H 3. A 100-fold enhanced oxidation peak current was observed at Er-GOBi/GCE when compared to that at bare GCE.Sensing performance of Er GO-Bi/GCE was optimized by varying peak current dependent parameters.Linear relationship between the peak current and concentration of GMB was observed in the range of 0.1–51.1 mmol/L in differential pulse voltammetric method and 2.1–61.1 mmol/L in linear sweep voltammetric method. The practical utility of the proposed sensor, Er-GOBi/GCE was demonstrated by determining GMB in pharmaceutical formulations and spiked urine samples.     

Spectrophotometric Study on the Interaction of Water with Chloranilic Acid and its Analytical Application

The reaction between chloranilic acid and water in alcohol was studied spectrophotometrically. The conditions of reaction were investigated in detail. The stable purple complex with an absorption wavelength at 530 nm was produced from the reaction between chloranilic acid and water. As a method for determination of H2O, Beer‘s law was obeyed in range of 0-6.0 % or 0-8.0 % (V/V) with the detection limit of 0.13 %. The relative standard deviation (RSD) was less than 2 %. The proposed method has been applied to determination of tracea mount of water in ethanol, flour and food flavoring, respectively. The recoveries of water in samples were 97～102%.     

Determination of resveratrol in red wine by solid phase extraction-flow injection chemiluminescence method

A sensitive flow injection chemiluminescence method has been developed for the detection of resveratrol in red wine based on the fact that resveratrol can greatly enhance chemiluminescence reaction between KMnO_4 and HCHO in sulfuric acid medium. Analytes were pre-concentrated on solid sorbents (C_(18) solid-phase extraction cartridges).Under the optimum conditions,the proposed method allows the measurement of resveratrol over the range of 1.32×10~(-8) to 1.32×10~(-5) mol/L with a detection limit of 3.30×10~(-9) mol/L,and the relative standard deviation for 1.32×10~(-5) mol/L resveratrol (n=11) is 3.8%.This method has been successfully applied for the determination of the resveratrol in red wine.Furthermore,the possible reaction mechanism was also discussed.     

Recent progress in quantifying substituent effects

This paper summarizes significant progress in quantifying organic substituent effects in the last 20 years. The main content is as follows: (1) The principle of electronegativity equalization has gained wide acceptance, and has been used to calculate the intramolecular charge distribution and inductive effect of groups. A valence electrons equalization method was proposed to compute the molecular electronegativity on the basis of geometric mean method, harmonic mean method, and weighted mean method. This new calculation method further extended the application of the principle of electronegativity equalization. (2) A scale method was established for experimentally determining the electrophilic and nucleophilic ability of reagents, in which benzhydryliumions and quinone methides were taken as the reference compounds, and the research field was extended to the gas phase conditions, organometallic reaction and radicals system. Moreover, the nucleophilicity parameters N and electrophilicity parameters E for a series of reagents were obtained. The definition and quantitative expression of electrophilicity index and nucleophilicity index were proposed theoretically, and the correlation between the parameters from experimental determination and the indexes from theoretical calculation was also investigated. (3) The polarizability effect parameter was initially calculated by empirical method and further developed by quantum chemistry method. Recently, the polarizability effect index of alkyl (PEI) and groups (PEI X ) were proposed by statistical method, and got wide applications in explaining and estimating gas-phase acidity and basicity, ionization energy, enthalpy of formation, bond energy, reaction rate, water solubility and chromatographic retention for organic compounds. (4) The excited-state substituent constant ex CC obtained directly from the UV absorption energy data of substituted benzenes, is different from the polar constants in molecular ground state and the radical spin-delocalization effects constants in molecular radical state. The proposed constant ex CC correlated well with the UV absorption energy of many kinds of organic compounds, such as 1,4-disubstituted benzenes, substituted stilbenes, and disubstituted N-benzylidenebenzenamine. (5) The establishment of the steric shielding effect distinguished the three traditional steric effects. The stereoselectivity index C i was proposed to quantify the stereoselectivity of the addition reaction of carbonyl with nucleophilic reagent. The shielding parameter S R was defined to quantitatively express the specific surface of the reaction center screened by a group. Further, the Topological Steric Effect Index (TSEI) of a group was proposed on the basis of the relative specific volume of reaction center screened by the atoms of substituents. These parameters can be applied in estimating the intramolecular dihedral angles, stereoselectivity of reaction, enthalpies of formation of alkenes and alkylbenzene, acidity of substitutedimidazolium ionic liquid, and the reaction rate of alkane and hydroxyl radical. In addition, some suggestions and prospects for further studies on quantifying the organic substituent effects were presented in this paper.     

Fluorometric determination of nonylphenol in water samples enriched with zirconium doped titanium dioxide nanotubes solid phase extraction

This paper developed a fluorometric method for the sensitive determination of nonylphenol in water samples by preconcentration with zirconium doped titanium dioxide nanotubes solid phase extraction.The parameters on extraction that would influence the enrichment performance such as the kind and volume of eluent,sample pH,sample flow rate,and sample volume were optimized in detail.Under the optimal conditions,the proposed method provided an excellent linear range of 1-150 mg/L and good LOD of 0.076 mg/L.The relative standard deviation(RSD,n = 6) was 2.8%.Proposed method was also used for the analysis of real water samples and the spiked recoveries were satisfied in the range of 98.7-103%.