Annealing effects on magnetic properties of acicular hematite nanoparticles

The effect of transformation on the structure and magnetic properties of -Fe₂O₃ acicular nanoparticles (major axis, 330 nm; minor axis, 70 nm) has been investigated. The particles were prepared by hydrolysis and polymerization in an aqueous solution of FeCl₃. Particles in the as-prepared sample are constituted by sub-units of 3–5 nm. The results indicate that the changes in the magnetic properties of the samples under thermal treatments (e.g. Morin transition, superparamagnetic behaviour) are mainly caused by the coalesce of the sub-units and by the variation of the crystallinity of nanoparticles.     

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.     

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     

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。     

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.     

桑色素光度法测定痕量铝和聚丙烯酰胺

基于聚丙烯酰胺（ＰＡＭ）作为增稳剂时,Ａｌ＾３＋叠色素（ｍｏｒｉｎ）之间的显色反应,提出了一种简便,快速,高灵敏测定痕量铝的光度法,络合物组成比为Ａｌ：ｍｏｒｉｎ＝１：２;表观摩尔吸光系数ε４０８＝６．３×１０＾７Ｌ．ｍｏｌ＾－１．ｃｍ＾－１;铝浓度在０．０４－０．２８μｇ／Ｌ范围内服从比尔定律;检测限４．０×１０＾－１０ｇ／Ｌ。     

荧光分光光度法分析天然水中铝形态的研究

基于衍生试剂与天然水中原生有机质之间对铝的竞争配位,建立了用荧光分光光度法区分天然水中铝形态的方法。以铬蓝黑R和桑色素为分析试剂可以测定无机单核铝,而以8-羟基喹啉为分析试剂则可以测定总单核铝,实验结果与用Driscoll方法所得到的结果基本一致。为有目的地选择分析试剂,在天然水自身pH条件下进行铝形态的直接分析提供了一个新的方法选择。相对来说,荧光分光光度法操作更加简单,条件温和,对原始样品几乎没有扰动,天然水中铝形态分析的结果更符合真实情况。     

桑色素-过氧化氢体系催化光度法测定痕量锰的研究

本文建立了基于过氧化氢氧化桑色素这一新指标反应催化光度法测定痕量锰的新方法。该法的检出限为０．００４μｇ／ｍＬ,线性范围为５～８０ｎｇ／ｍＬ。该法已用于白酒中锰的测定。     

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%。