紫外可见分光光度法对湖泊沉积物中的色素测定

介绍了如何从湖泊沉积物中提取出叶绿素、胡萝卜素、颤藻黄素和蓝藻叶黄素等几种色素的方法以及用外可分光光度法对其进行测定；同时介绍了沉积物中几种色素含理的计算方法。最后对云南滇池沉积物中色素含量进行了分析测试，并说明色素分析在沉物研究方面的意义。     

紫外可见分光光度法快速测定苯硫酚

设计合成一种全新的苯硫酚检测探针。以试卤灵钠为主要原料,在三乙胺催化下与2,4-二硝基氯苯合成了7-(2’,4’-二硝基苯氧基)-3H-吩噁嗪-3-酮,产率为41.7%。在p H 7.4的磷酸盐缓冲溶液中,该化合物能与苯硫酚发生亲核取代反应,反应体系在可见光区λ=580 nm处有强吸收。该探针测定苯硫酚的线性范围为0.1~20μmol/L,检出限为8.9×10–8 mol/L,精密度为3.7%(n=8),回收率为106%。该方法可快速检测环境及生物体中的苯硫酚。     

汉字紫外—可见分光光度法教学模拟系统

近年来,随着计算机技术的不断发展,计算机应用涉及到越来越厂泛的领域。计算机模拟技术就是其中的一个方面。计算机化学教学模拟不仅具有可以利用计算机屏幕显示形象、生动的特点,还可再现出化学过程的科学原理及其现象,便于学习者理解、掌握,而且还具有很大的实用意义。因为计算机化学实验操作模拟允许使用者有针对性地、反复地熟悉某一特定的实验步骤(或仪器操作),而无需一些繁杂的前准备、     

沉积物中铝含量的流动注射分光光度法测定

本文根据自行设计的一套流动注射（ＦＩＡ）双光束分光光度计装置，研究了河底沉积物中微量铝测定的适宜条件，设备简单，操作容易。灵敏度较普通光度法提高近１倍，进样速率为８０－９０次／ｈ，相对标准偏差小于０．９％。     

紫外可见分光光度法测定田七花中总黄酮含量

建立了分光光度法测定田七花中黄酮含量的方法.采用分光光度法,以芦丁为对照品,在波长510nm处对样品中的总黄酮进行含量测定.样品总黄酮在浓度0～50μg/mL范围内线性关系良好,其回归方程为A=11.069C-7.143×10-4;R=0.9993.该方法可作为田七花中总黄酮含量的测定的方法之一.     

紫外可见分光光度法测定酶解桑葚酒中多糖含量

采用紫外可见分光光度法测定酶解桑葚酒中的多糖含量。向酶解桑葚酒中加入硫酸,使样品中的多糖水解成单糖,并迅速脱水生成糖醛衍生物,加入苯酚作为显色剂,检测波长为490 nm,标准工作曲线线性方程为y=0.056 8x–0.035,相关系数r=0.999 4。测定结果的相对标准偏差为0.03%(n=5),平均加标回收率为98.69%。该方法用于检测酶解桑葚酒中多糖含量,简便、快速。     

紫外分光光度法测定啤酒中α-酸的含量

采用紫外分光光度法测定了8种不同品牌啤酒中α-酸的含量。实验考察了不同有机溶剂、介质酸度对α-酸紫外吸收的影响。结果表明:α-酸在279nm处有较强的吸收,方法线性范围在10～50μg/mL,检出限2.6μg/mL,相对标准偏差2.01%。8种不同品牌啤酒中α-酸的含量(μg/mL)为:百威啤酒(392.07)蓝带啤酒(383.82)崂山啤酒(373.72)雪花啤酒(238.26)司陶特黑啤酒(99.49)燕京啤酒(55.16)青岛啤酒(54.91)哈尔滨啤酒(35.05),平均偏差小于5%。用标准加入法测定其回收率,样品回收率范围在93.81%～105.15%之间。     

紫外-可见分光光度法测定药物胶囊中盐酸氨基葡萄糖

基于盐酸氨基葡萄糖(GSM)与镍(Ⅱ)在碱性介质中生成配合物,在波长219nm处有其最大吸收的现象作了进一步验证。将此反应用于紫外-可见分光光度法测定其药物胶囊中GSM含量。测定时,将一颗GSM胶囊中的药物颗粒取出称重后(每颗药物中GSM的质量的标示量为0.24g)溶于水中并定容至250 mL。取此溶液5.00 mL置于50 mL容量瓶中,相继顺序加入0.10mol·L~(-1)氢氧化钠溶液10mL和1.0×10~(-2) mol·L~(-1)硫酸镍溶液2.00mL,用0.10mol·L~(-1)氢氧化钠溶液定容,在20℃水浴中反应15min。在波长219nm处测量其吸光度。GSM的浓度在6.00×10~(-4)～4.00×10~(-3) mol·L~(-1)内与其相应的吸光度呈线性关系,其检出限(3S/N)为4.10×10~(-5) mol·L~(-1)。以GSM胶囊样品溶液为基体,按标准加入法在4个浓度水平上进行回收试验,测得回收率为80.0%～110%。测定值的相对标准偏差(n=5)均小于0.2%。按此方法对药物实样进行分析,测得其GSM浓度为7.26×10~(-4) mol·L~(-1),换算成胶囊中GSM的质量为0.238 6g,与其标示值相符。     

浊点萃取-紫外可见分光光度法测定痕量钴

浊点萃取(Cloud-Point Extraction,简称CPE)是近年来出现的一种新兴的液-液萃取技术,该法以表面活性剂胶束水溶液的溶解性和浊点现象为基础,通过改变实验参数如溶液pH值、离子强度、温度等引发相分离,将疏水性物质与亲水性物质分离,同时起到富集的作用.     

微波加热快速测定腐植酸总量

利用微波加热技术，在密闭容器内通过压力浸提、消解试样、能大大加快分析速度，本实验测定了不同煤样中的腐植酸总量，讨论了功率、时间、酸度等因素对分析结果的影响，并与标准方法相对照，用ｔ－检验法及Ｆ－检验法检验，没有明显差异，结果令人满意，该法具有省时、省力、经济、不污染环境，宜于批量分析，便于普及推广等优点。     

乙二醛与乙醛酸的比值导数波谱法同时测定

利用比值导数波谱法同时检测乙二醛(GLY)和乙醛酸(AGLY),为GLY催化氧化过程的实时、快速分析提供了新的手段.研究表明,GLY的催化氧化副产物草酸(OX)对GLY、AGLY的分析没有干扰.AGLY的质量浓度(p)在1.47～7.33 ms/L范围内与其吸光度比值导数值(y)呈良好的线性关系,回归方程:y=0.016 31 p-0.013 5,r=0.999 0(n=5);GLY的质量浓度在1.68～9.13 mg/L范围内与其吸光度比值导数值呈良好的线性关系,回归方程:Y=-0.5374 P 0.010 4,r=1(n=5).AGLY与GLY的质量比为0.37～3.35时,AGLY的回收率为95%～103%,GLY的回收率为98%～105%.     

太湖沉积物中酮的提取、分离及GC-MS测定

用索氏抽提法提取了太湖沉积物中的可溶性有机质,用不同极性溶剂在硅胶／氧化铝柱上分离了饱和烃,芳烃,酮馏分。利用ＧＣ－ＭＳ对酮组份进行了分析。沉积物中检出了一系列呈等间距分布的正构烷基－２－酮：Ｃ１４至Ｃ３３,主峰为Ｃ２９,具有强烈的奇碳数优势。     

弱碱性大孔吸附树脂对腐殖酸的吸附

研究了腐殖酸分子量对弱碱性大孔树脂吸附腐殖酸的影响, 阐明了溶液中小分子芳环化合物(苯酚)及盐含量对树脂吸附腐殖酸的影响机制. 结果表明, 树脂对低分子量腐殖酸的吸附效果要优于高分子量腐殖酸; 低浓度苯酚在溶液中可以促进树脂吸附腐殖酸, 但溶液中苯酚浓度过高会对树脂吸附腐殖酸产生抑制作用; 溶液中的盐对树脂吸附腐殖酸的影响取决于溶液的pH值.     

裂解技术研究Pahokee泥炭腐殖酸的组成和来源特征

通过原位裂解．色谱．质谱(Py-GC-Ms)技术,应用直接裂解和原位裂解甲基化两种手段,从分子水平研究了Pahokee泥炭腐殖酸的来源和组成特征,结果表明：两种裂解方式都得到大量芳香结构的裂解产物,少量游离脂肪酸和脂肪链状结构裂解产物,以及一些含氮或呋喃结构的裂解产物,表明Pahokee泥炭腐殖酸的形成主要与陆生木质素有关,而微生物和其他物质对腐殖酸形成也有重要贡献。     

Determination of Lead and Cadmium by Stripping Voltammetry After Separation from Humic Acid by Thin-Layer Chromatography

Abstract

Interferences resulting from the presence of humic acid (HA) and other surface-active substances in a sample matrix decrease the reliability of Pb and Cd determinations obtained by square-wave anodic stripping voltammetry (SWASV). The implementation of thin-layer chromatography (TLC) prior to SWASV minimizes the effect of these interferents by physically separating Pb and Cd from the sample matrix prior to analysis. The determination of both Pb and Cd was shown to be feasible after TLC separation from laboratory standards spiked with 100 ppm humic acid and from a lake water sample spiked with 1 ppm of Pb and Cd.     

Flow Injection Determination of Humic Acid with Chemiluminescence Detection

Abstract

A very sensitive and fast flow injection chemiluminescence method, based on the oxidation of humic acid (HA) by 1,3‐dibromine‐5,5‐dimethylhydantion in the presence of glycine in alkaline medium, was developed for the determination of trace humic acids in water. A wide calibration range from 0.001 to 1.0 µg mL^?1 was obtained at the optimized conditions and the detection limit was as low as 0.5 ng mL^?1 of humic acids. Most of the foreign substances tested showed relatively high tolerance levels and the proposed method was successfully applied to the determination of humic acid in river water and tap water.     

Rapid Determination of HAAs Formation Potential of the Reaction of Humic Acid with Chlorine or Chlorine Dioxide

On the basis of gas chromatography(GC) coupled with a short capillary column and an electron capture detector(ECD), a simple and rapid method for the determination of five haloacetic acids(HAAs) in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formation potential(HAAFP) of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroacetic acid(DCAA) and Trichloroacetic acid(TCAA), which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9 μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with chorine, may exceed MCL of 60 μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfection/disinfection by-products(D/DBP) rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 6 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.