化学发光分析法同时测定水中钴和锰的研究

利用Mn2+和Co2+对NaIO4-鲁米诺发光体系有催化作用,催化后体系的发光强度与Mn2+或CO2+浓度在一定范围内成线性关系的特点,采用流动注射.化学发光法对Co和Mn进行同时测定.Mn2+和Co2+催化NaIO4-鲁米诺发光体系的光谱重叠严重,用常规方法难以进行分析,本文运用蚂蚁算法(ACA)对数据进行优化处理,获得Mn2+回收率在97.8%～103.6%之间,Co2+的回收率在96.0%～105.0%之间.     

基于石墨烯/聚半胱氨酸的表面吸附和电化学催化高灵敏检测色氨酸

以氧化石墨烯和半胱氨酸为前驱体,利用循环伏安法还原-聚合构建了还原氧化石墨烯（rGO）/聚半胱氨酸（L-cys）修饰玻碳电极（GCE）(rGO/L-cys/GCE)。研究了色氨酸在该修饰电极上的电化学行为。结果表明,基于rGO优异的电子传导性能、强吸附富集及L-cys对色氨酸的催化作用,rGO/L-cys/GCE显著提高了色氨酸检测的灵敏度。最优实验条件下,色氨酸浓度在0.03～10.0μmol/L范围内,峰电流与其浓度呈良好线性关系,检出限为8 nmol/L。将该修饰电极用于香蕉中色氨酸含量的测定,回收率为93.8%～105.0%。该修饰电极构建方法简便且灵敏度高,可用于实际样品测定。     

线扫伏安法同时测定5-羟基色氨酸和色氨酸

研究了色氨酸和5-羟基色氨酸在玻璃碳电极上的电化学行为,研究了不同pH、静置时间、扫描速度以及表面活性剂等的影响,探讨了色氨酸和5-羟基色氨酸在玻璃碳电极上的氧化机理,建立了线扫伏安法同时测定色氨酸和5-羟基色氨酸的方法.实验发现,在含3.33×10-4 mol/L十二烷基磺酸钠的0.1mol/L柠檬酸(pH=4.50)介质中,5-羟基色氨酸和色氨酸分别在 0.675V和 1.070V产生一灵敏的氧化峰.对5-羟基色氨酸,相应的氧化峰的峰高与浓度在2.40×10-5 mol/L～8.00×10-4 mol/L范围内呈良好的线性关系,线性相关系数为0.9994;对色氨酸,其氧化峰的峰高与浓度在2.40×10-5 mol/L～6.40×10-4 mol/L浓度范围内呈良好的线性关系,线性相关系数为0.9929.该方法测量2.00×10-4 mol/L色氨酸和5-羟基色氨酸的相对标准偏差分别为3.2%和3.8%(n=10).     

测定色氨酸的流动注射阻抑化学发光新体系

基于硫酸介质中一定量的色氨酸(Trp)对铱配合物[(dpci)2 Ir(pca)](dpci=3,4-二苯基邻二氮杂萘,pca-吡啶-2-羧酸)-Ce(Ⅳ)-Na2 SO3体系的化学发光阻抑作用,建立了流动注射化学发光法测定Trp的新方法.在优化的实验条件下,化学发光抑制程度与Trp浓度在1.5×10-7～1.0×10...     

镀铜锌粒还原-流动注射-化学发光同时测定两种价态的铁

建立了镀铜的锌粒在线还原微柱，还原Fe3+成Fe2+，鲁米诺中加EDTA增强鲁米诺-溶解氧-铁（Ⅱ）系统的发光强度，同时测两种价态的铁，提高灵敏度160倍，线性范围均为1×10－9～1×10－5mol／L．RSD≤6．0％，Fe3+和Fe2+的检出限分别为3．5×10－10和2．7×10-10mol／L。每小时可测定60个试样，测定结果与标准方法无显著差异。     

比值导数荧光光谱法同时测定色氨酸和5-羟基色氨酸

建立了比值导数荧光光谱法同时测定色氨酸和5-羟基色氨酸的方法。在比值导数荧光光谱法中,色氨酸浓度在4.0×10-6~2.0×10-5mol/L范围内比值导数荧光光谱峰高与其浓度成正比,线性相关系数为0.9901,检出限为1.3×10-7mol/L。5-羟基色氨酸浓度在4.0×10-8~2.0×10-5mol/L范围内比值导数光谱峰高与其浓度成正比,线性相关系数为0.9996,检出限为1.3×10-8mol/L。同时测定了实际样品中的色氨酸和5-羟基色氨酸,测定结果与高效液相色谱法有良好的一致性。     

Ce(Ⅳ)-吐温40-色氨酸化学发光体系的研究与应用

实验观察到在酸性条件下,色氨酸能够增强Ce(Ⅳ)和吐温40的化学发光反应,其发光强度的增加与色氨酸含量在一定的范围内呈线性关系,据此建立了测定色氨酸的化学发光分析新方法.采用顺序注射技术进样,将试样和试剂的消耗降至微升范围内,明显提高了分析速度.考察了各种实验参数的影响和可能的反应机理,此反应的发光体为Tween 40的中间氧化产物.在试样体积70 μL、吐温40浓度为5%、试剂Ce(Ⅳ)体积80 μL、浓度为1.0 mmol/L、检测流速为1.8 mL/min的条件下,线性范围为2.0×10-7～1.4×10-5 mol/L; 检出限(3σ)为8.8×10-8 mol/L; 对6.0×10-6 mol/L色氨酸进行9次测定的相对标准偏差为1.3%.啤酒和血清中色氨酸含量测定的回收率为91.2%～102%.     

L－色氨酸－H_2O_2－ClO~－－CTAB流动注射化学发光反应的研究

本文采用反相流动注射法研究了在阳离子表面活性剂ＣＴＡＢ存在下，Ｌ－色氨酸－Ｈ２Ｏ２－ＣｌＯ－体系的化学发光行为，对影响化学发光强度的诸因素和表面活性剂的增强作用进行了试验和探讨，建立了化学发光测定Ｌ－色氨酸的新方法。线性范围１．０×１０－８～８．０×１０－６ｍｏｌ·Ｌ－１，检测限为４．０×１０－９ｍｏｌ·Ｌ－１（Ｓ／Ｎ＝２）。对合成试样中三种浓度的Ｌ－色氨酸测定的回收率在９７％～１０６％之间，相对标准偏差小于４％。     

Flow-injection chemiluminescence determination of tryptophan using galangin-potassium permanganate–polyphosphoric acid system

A high sensitive flow-injection chemiluminescence （FI-CL） method for the determination of tryptophan has been developed. The method is based on the chemiluminescence reaction of galangin-potassium permanganate-tryptophan in polyphosphoric acid （PPA） media. Under the optimized conditions, tryptophan was determined in the range 0.05-10 μg/mL with the detection limit （3tr） of 5.0 × 10^-3 μg/mL. The relative standard deviation （RSD） was 1.0% for 11 replicate determinations of 1.0 μg/mL tryptophan. Three synthetic samples were determined selectively with recoveries in the range from 99.6% to 102.0% in the presence of other amino acids.     

Simultaneous determination of rifampicin and isoniazid by continuous-flow chemiluminescence with artificial neural network calibration

In this paper a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of rifampicin and isoniazid. This method is based on the different kinetic spectra of the analytes in their CL reaction with alkaline N-bromosuccinimide as oxidant. The CL intensity was measured and recorded every second from 1 to 300 s. The data obtained were processed chemometrically by use of an artificial neural network. The experimental calibration set was 20 sample solutions. The relative standard errors of prediction for both analytes were approximately 5%. The proposed method was successfully applied to the simultaneous determination of rifampicin and isoniazid in a combined pharmaceutical formulation.     

Simultaneous chemiluminescence determination of promazine and fluphenazine using support vector regression

In this work, chemiluminescence (CL) behaviors of two selected phenothiazines, namely promazine and fluphenazine hydrochloride, were investigated for their simultaneous determination using oxidation of Ru(bipy)₃²⁺ by Ce⁴⁺ ions in acidic media. This method is based on the kinetic distinction of the CL reactions of fluphenazine and promazine with Ru(bipy)₃²⁺ and Ce⁴⁺ system in a sulfuric acid medium. Least square support vector regression models were constructed for relating concentrations of both compounds to their CL profiles. The parameters of the model consisting of σ² and γ were optimized using all possible combinations of σ² and γ to select the model with the minimum root mean square cross validation. Under optimized conditions, the univariate calibration curve was linear over the concentration ranges of 0.4-30.0 μg mL⁻¹ and 0.07-5.0 μg mL⁻¹ with detection limits of 0.1 μg mL⁻¹ and 0.04 μg mL⁻¹ for promazine and fluphenazine, respectively. The influence of potential interfering substances on the determination of promazine and fluphenazine were studied. The proposed method was used for simultaneous determination of both compounds in synthetic mixtures and in spiked human plasma.     

Direct chemiluminescence determination of cysteine in human serum using quinine-Ce(IV) system

A simple, sensitive and selective chemiluminescence (CL) method was developed for the determination of cysteine. This method is based on that the weak CL of cysteine oxidized with cerium (IV) can be greatly enhanced by quinine. The calibration curve was linear over the range 3.5×10⁻⁹-3.5×10⁻⁶ M with a detection limit of 2.5×10⁻⁹ M (S/N=3). The RSD was found to be 8.4% by 10 replicate determinations of 2.9×10⁻⁸ M cysteine. Due to high sensitivity, the proposed method can be used directly to determine the total concentration of cysteine in human serum through simply diluting the sample for a thousand fold. The obtained result was in agreement with that given by amino acid autoanalyzer. The present method does not require any separation, showing a simpler analytical characteristic. The mechanism of the CL reaction was also discussed.     

Determination of cysteine in a pharmaceutical formulation by flow injection analysis with a chemiluminescence detector

A simple and convenient flow injection-chemiluminescence (FI-CL) method for the determination of cysteine is reported, based on a fast and strong CL in a basic luminol-cysteine-NaIO₄ solution. The linear range was 1.0×10⁻⁸ to 1.0×10⁻⁶ M with a detection limit (3s) of 5×10⁻⁹ M, which was 100 times more sensitive than previously reported CL methods. Singlet oxygen, hydroxyl radical and hydrogen peroxide were suggested to be produced in this reaction and were responsible for the CL of cysteine. This simple method has been successfully applied for the determination of cysteine in a pharmaceutical formulation.     

Simultaneous determination of ascorbic acid,dopamine and uric acid based on tryptophan functionalized graphene

A new type of tryptophan-functionalized graphene nanocomposite (Trp-GR) was synthesized by utilizing a facile ultrasonic method via π–π conjugate action between graphene (GR) and tryptophan (Trp) molecule. The material as prepared had well dispersivity in water and better conductivity than pure GR. The surface morphology of Trp-GR was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) were investigated by cyclic voltammetry (CV) on the surface of Trp-GR. The separation of the oxidation peak potentials for AA–DA, DA–UA and UA–AA was about 182 mV, 125 mV and 307 mV, which allowed simultaneously determining AA, DA, and UA. Differential pulse voltammetery (DPV) was used for the determination of AA, DA, and UA in their mixture. Under optimum conditions, the linear response ranges for the determination of AA, DA, and UA were 0.2–12.9 mM, 0.5–110 μM, and 10–1000 μM, with the detection limits (S/N = 3) of 10.09 μM, 0.29 μM and 1.24 μM, respectively. Furthermore, the modified electrode was investigated for real sample analysis.     

Simultaneous determination of three organophosphorus pesticides residues in vegetables using continuous-flow chemiluminescence with artificial neural network calibration

In this article, a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of three organophosphorus pesiticides residues. This method is based on the fact that organophosphorus pesticides can be decomposed into orthophosphate with potassium peroxodisulphate as oxidant under ultraviolet radiation and that the decomposing kinetic characteristics of the organophosphorus pesticides with different molecular structure are significantly different. The produced orthophosphate can react with molybdate and vanadate to form the vanadomolybdophosphoric heteropoly acid, which can oxidize luminol to produce intense CL emission. The CL intensity of the solution was measured and recorded every 2 s in the range of 0-250 s. The obtained data were processed chemometrically by use of a three-layered feed-forward artificial neural network trained by back-propagation learning algorithm, in which input node, hidden node and output nodes were 65, 21 and 3, respectively. The proposed multi-residue analysis method was successfully applied to the simultaneous determination of the three organophosphorus pesticides residue in some vegetables samples.     

Kinetic determination of cysteine and thiosulphate by inhibition of Hg(II) catalyzed ligand substitution reaction

The sulphur containing inhibitors (I), cysteine (Cys) and sodium thiosulphate (THS), have been found to inhibit Hg(II) catalyzed exchange of cyanide in hexacyanoferrate(II) by nitroso-R-salt (NRS). The inhibitory effect of both the ligands are attributed to their binding tendencies with Hg(II) leading to the formation of catalyst-inhibitor (C-I) complex. The reactions have been followed spectrophotometrically in aqueous medium at 720 nm by noting the increase in absorbance of the green colour product, [Fe(CN)₅NRS]³⁻ at pH 6.50 ± 0.02, temp 25.0 ± 0.1 °C and ionic strength (μ) 0.1 M (KNO₃). A most plausible mechanistic scheme involving the role of analytes (inhibitors) has been proposed. The values of equilibrium constants for complex formation between catalyst-inhibitor (K_CI), catalyst-substrate (K_S) and Mechaelis-Menton constant (K_m) have been computed from the kinetic data. The linear calibration curves have been established between absorbance and inhibitor concentrations under specified conditions. Cys and THS have been determined in the range 1-5 × 10^− 7 M and 4.9-16.9 × 10^− 7 M respectively. The detection limits have been computed to be 1 × 10^− 7 M and 4.9 × 10^− 7 M for Cys and THS, respectively.     

流动注射化学发光法测定有机磷农药残留量

基于K2S2O8在紫外光催化下可将有机磷消解为正磷酸盐,而正磷酸盐在酸性条件下可与钼酸盐、钒酸盐形成具有氧化性的磷钼钒杂多酸,其可直接氧化碱性鲁米诺产生强的化学发光,本文结合流动注射技术,提出了一种测定有机磷农药残留量的化学发光新方法。其线性范围为1.0×10-9~1.0×10-5g/mL,检出限为8.0×10-10g/mL。对2.0×10-7g/mL的磷进行11次平行测定,其RSD为4.8%。并分别测定了3种有机磷农药。     

Flow-injection chemiluminescence simultaneous determination of cobalt(II) and copper(II) using partial least squares calibration

A flow-injection chemiluminescence (CL) system is proposed for simultaneous determination of Co²⁺ and Cu²⁺ using partial least squares (PLS) calibration. This method is based on the fact that both Co²⁺ and Cu²⁺ catalyse the CL reaction of luminol-H₂O₂, and that their kinetic characteristics of Co²⁺ and Cu²⁺ are significantly different in the luminol-H₂O₂ system. The CL intensity was measured and recorder at different reaction times of luminol-H₂O₂Co²⁺Cu²⁺, and the obtained data were processed by the chemometric approach of partial least squares. The experimental calibration set was composed of 16 sample solutions using an orthogonal calibration design for two component mixtures. The proposed method offers the potential advantages of high sensitivity, simplicity and rapidity for Co²⁺ and Cu²⁺ determination, and was successfully applied to the simultaneous determination of both analytes in real water sample. The present paper demonstrated that the simultaneous determination of two metal ions without any prior separation has been possible using flow-injection CL system.