桑色素荧光分光光度法测定水和保健饮料中痕量锗

本文提出了测定水和保健饮料中痕量锗的桑色素荧光分光光度法。检出限分别为0.2μg/L和0.7μg/L,线性范围分别为1.0～25μg/L和5.0～30μg/L,平均回收率分别为97.2％～104.5％和98.8％～104.8％,相对标准偏差分别为3.66％。2.87％方法简便,准确高度,精密度好,共存离子干扰小。     

Stripping Voltammetric Determination of Zirconium with Complexing Preconcentration of Zirconium(IV) at a Morin‐Modified Carbon Paste Electrode

A sensitive, selective and economic stripping voltammetry is described for the determination of trace amounts of zirconium at a morin‐modified carbon paste electrode (morin‐MCPE). Zirconium(IV) can be preconcentrated on the surface of the morin‐MCPE due to forming the Zr(IV)–morin complex. The complex produces two second‐order derivative anodic peaks at 0.69 V (vs. SCE) and 0.75 V when linear‐scanning from 0.0 to 1.0 V. The optimum analytical conditions are: 2.2 mol L^?1 HCl, 0.0 V accummulation potential, 90 s accummulation time, 250 mV s^?1 scan rate. A linear relationships between the peak currents at 0.75 V and the Zr(IV) concentration are in the range of 2.0×10^?8 to 3.0×10^?6 mol L^?1. The detection limit is 1.0×10^?8 mol L^?1 (S/N=3) for 120 s accumulation. The RSD for determination of 4.0×10^?7 mol L^?1 Zr(IV) is 4.8% (n=8). The proposed method has been applied to determine zirconium in ore samples, unnecessarily extracted.     

Novel Phosphate—sensitive Fluorescent Composite Matrix

Via several techniques to modify sensitive matrix for inhabiting the leakage of fluoreseent indicator,a new stable scnsing material for monitoring phosphates has been prepared and applied to the measurement of phosphates in artificial seawater.It is based on the reaction of PO4^3- with Al（Ⅲ）-Morin that leads to the fluorescence quenching of the composite matrix.At pH value 4.0and the salinity value 25.0,the response time of output signal having reached the steady state is less than 300 seconds.Its calibration graph is gained in the range of H2PO4^- mass concentration from 1.50 to 7.00μg/mL with the limit of detection (3σ/K)0.02μg/mL.When it was used to measure phosphates in artificial seawater,the recovery ranged from 96.78% to 102.09%.Being stored under the proper condition,the membranes maintain sensitive for 90-120days,and are able to be used for 50-80times with indicator supplement.     

α-Fe_2O_3纳米粒子Morin相变的Raman光谱研究

本文首次用Raman光谱法研究了粒子尺寸和Co2 +包附对α-Fe2 O3纳米粒子Morin相变温度TM的影响机制。测量结果显示纳米粒子α -Fe2 O3的振动模相对大块样品发生了红移和宽化 ,粒子愈小红移和宽化愈显著。表明表面Fe3+离子与配位氧离子的键距增大 ,键长呈从体相Fe-O键长过渡到表面Fe -O键长的某种分布。这种小尺寸引起的键长改变导致α -Fe2 O3粒子的单离子各向异性能减小 ,因此降低了样品的TM。分析显示Co2 +包附导致α -Fe2 O3粒子TM 的大幅下降可能是由单离子各向异性的减小和Co2 +与Fe3+之间的磁偶极子相互作用各向异性共同作用的结果     

基于聚乙烯亚胺碳纳米点的桑色素比率型荧光探针

利用水热合成法制备了一种基于聚乙烯亚胺的荧光碳纳米点, 用光谱方法研究了其对桑色素的识别作用. 结果表明, 该碳纳米点对桑色素具有比率型荧光响应, 且响应速度快、 选择性和灵敏度高、 抗干扰能力强. 将桑色素加入到碳纳米点溶液中后, 碳纳米点自身的荧光(460 nm)立即被猝灭, 同时在555 nm处出现新的荧光发射峰并逐渐增强; 其新发射峰(555 nm)与原发射峰(460 nm)的强度比值在此过程中呈线性增加. 基于此, 在1.0×10^-6~4.0×10^-5 mol/L浓度范围内, 可实现对桑色素的检测, 该比率荧光响应非常灵敏, 检出限可达3.0×10^-8 mol/L. 另外, 该碳纳米点与常见金属离子、 氨基酸及其它具有类似桑色素结构的黄酮醇均不反应, 显示出对桑色素的高选择性. 该检测方法的荧光强度随桑色素浓度的增加而逐渐增强, 并伴随着由蓝色到黄色的荧光颜色变化, 可实现对桑色素的可视化检测; 同时该碳纳米点还可用于稀释胎牛血清中桑色素的定量检测.     

Cu(Ⅱ)-桑色素-十六烷基三甲基溴化铵荧光体系测定微量Cu(Ⅱ)的研究

在H2SO4介质中,以十六烷基三甲基溴化铵(CTMAB)为增敏剂,微量Cu(Ⅱ)对桑色素的荧光具有明显的增强作用,据此建立了测定微量Cu(Ⅱ)的新方法。当最大激发波长和发射波长分别为417nm和497nm时,Cu(Ⅱ)在4.0~20ng/mL浓度范围内与桑色素荧光强度变化值(△F)呈线性关系,其检出限为0.39ng/mL。对12ng/mL Cu(Ⅱ)进行12次平行测定,相对标准偏差为0.76%。方法可用于不同环境水样中微量Cu(Ⅱ)的测定,回收率在96.1%~102.9%之间。     

桑色素分子印迹传感器的制备与应用

以邻氨基酚( o-AP)为功能单体,桑色素为模板分子,基于分子间的相互作用力,在金电极表面电聚合制备具有特异性识别孔穴的桑色素分子印迹传感器膜。采用循环伏安法( CV)、差分脉冲伏安法( DPV)等研究了分子印迹膜的性能和分子印迹效应。探索了聚合膜配比及聚合扫描圈数对传感器性能的影响,优化了洗脱时间和印迹时间。比较了此传感器对其结构相似物的选择性响应,发现其对桑色素检测具有良好的选择性。在最佳实验条件下,此传感器对桑色素浓度定量测定范围为0.05~1.70μmol/L,线性方程为I(μA)=1.0800lgc(mol/L)+9.3599, R=0.9934,检出限为0.01μmol/L。用此传感器测定黑茶样品中桑色素的含量,加标回收率为104.0%~108.0%。     

Interplay of surface conditions, particle size, stoichiometry, cell parameters, and magnetism in synthetic hematite-like materials

We have studied several synthetic hematite-like materials, produced via different reactions using various hydrothermal conditions and various temperatures of annealing in air, by bulk elemental analysis, weight loss measurements, scanning electron microscopy, powder X-ray diffraction, Mössbauer spectroscopy, and SQUID magnetometry. We conclude that hematite-like materials cannot be related to pure stoichiometric hematite via a single stoichiometric or physical parameter and that at least two degrees of freedom are required. This is most clearly seen when we introduce a plot of the cell parameter c versus the cell parameter a on which hematite-like materials do not fall on a single line but occupy an entire region that is bounded by hydrohematite-hematite and protohematite-hematite lines. A Morin transition boundary on this c-a plot separates a region where Morin transitions occur from a larger region where Morin transitions do not occur down to 4.2 K. Previous claims that particle size is the dominant factor controlling the Morin transition are understood in terms of correlations between stoichiometry and particle size that are produced at synthesis. Changing contents of incorporated molecular water and structural hydroxyls with associated cation vacancies have different characteristic effects on the crystal structure and move the sample coordinates in different directions on a c-a plot. It is also shown that an accessory sulphate content is adsorbed on the individual hematite crystallites and is not structurally incorporated. Mössbauer spectroscopy is used, as usual, to identify and characterize the spin structure. In addition, hyperfine field distributions from room temperature spectra, extracted by a new method, give a sensitive measure of sample conditions but not a unique one since several factors affect the extracted distributions in similar ways.     

Aluminum(III) selective potentiometric sensor based on morin in poly(vinyl chloride) matrix

Al³⁺ selective sensor has been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing neutral carrier morin as ionophore. Best performance was exhibited by the membrane having composition as morin:PVC:sodium tetraphenyl borate:tri-n-butylphosphate in the ratio 5:150:5:150 (w/w, mg). This membrane worked well over a wide activity range of 5.0 × 10⁻⁷ to 1.0 × 10⁻¹ M of Al³⁺ with a Nernstian slope of 19.7 ± 0.1 mV/decade of Al³⁺ activity and a limit of detection 3.2 × 10⁻⁷ M. The response time of the sensor is ∼5 s and membrane could be used over a period of 2 months with good reproducibility. The proposed sensor works well over a pH range (3.5-5.0) and demonstrates good discriminating power over a number of mono-, di- and trivalent cations. The sensor can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working activity range. The sensor has also been used in the potentiometric titration of Al³⁺ with EDTA and for its determination in zinc plating mud and red mud.