铁矿石中SiO_2,CaO,MgO,Al_2O_3的系统分析

以过氧化钠为熔剂 ,于铁坩埚内进行快速熔融试样 ,熔块以水浸取 ,硝酸溶解盐类 ,对铁矿石、球团矿、烧结矿中二氧化硅、氧化钙、氧化镁、三氧化二铝进行系统分析。与国家标准方法相比 ,本法具有操作简便 ,准确性好 ,速度快 ,成本低 ,测定范围宽等特点     

1-羟基-2-(5-氯-2-吡啶偶氮)-8-氨基-3,6-萘二磺酸与铜的显色反应研究

研究了新试剂1 羟基 2 (5 氯 2 吡啶偶氮) 8 氨基 3,6 萘二磺酸(5 Cl PAH)与铜(II)的显色反应。结果表明,在pH7.42～8.49的硼砂 盐酸缓冲体系中该试剂与铜(II)可形成1∶1的蓝色配合物,其最大吸收波长位于640nm处,表观摩尔吸光系数为ε640=3.12×104L·moL-1·cm-1,铜(II)浓度在0～12.5μg/10mL的范围内符合比耳定律。将方法用于铝合金样和标准水样中微量铜的测定,结果满意。     

野马追中总黄酮的测定

采用冷浸法、加热回流法和超声法3种提取方法提取了野马追中的总黄酮，用芦丁作为对照品，硝酸铝——亚硝酸钠紫外——可见分光光度法测定野马追中总黄酮含量．在选定的实验条件下，芦丁的浓度和吸光度呈良好的线性关系，标准曲线的相关系数为0．9999，测定的相对标准偏差为1．27%—1．63％，平均回收率为98．20％．该方法简便、快速、灵敏度高，并具有较好的精密度与准确度，适合中药总黄酮含量的测定．结果显示：野马追中含大量黄酮类化合物，含量在2％左右；不同提取方法比较，超声法黄酮的浸出率最高．     

光谱和电化学法研究栎精与DNA的相互作用

用紫外-可见光谱法、循环伏安法及线性扫描伏安法研究了栎精(QUE)与DNA在0·01 mol·L-1的NaOAc-HOAc缓冲溶液(pH=4.2)中的相互作用。研究表明,栎精本身具有良好的电化学行为,DNA的加入能导致栎精氧化还原峰电流显著降低。通过测定DNA引入前后体系的一些电化学参数的变化,说明DNA与栎精在该条件下结合生成了一种结合比n(DNA):n(QUE)=1:2的非电活性超分子化合物,条件结合常数为1.3×104。讨论了二者之间的结合模式,二者之间可能同时存在着静电作用和嵌入作用。     

甘草总黄酮提取工艺的研究

研究了甘草总黄酮的提取工艺.根据黄酮的性质,以最大限度的提取甘草总黄酮为目的,通过正交实验、验证实验和对照实验,确定甘草总黄酮提取的最佳方案为:甘草渣粉末20g,Ca(OH)2 0.8 g,液固比20:1,酸沉pH值2.5,提取时间2 h.以芦丁为标准品,用分光光度法测定甘草总黄酮最高提取率为2.56%.     

紫外分光光度计法测定铁矿石中全铁的不确定度评定

通过紫外分光光度计测定铁矿石中全铁的不确定度评定,分析了该方法测定过程中的不确定度来源,建立了数学模型,并计算了各不确定度分量、合成不确定度、标准不确定度等。该方法适用于评定测量低含量全铁的不确定度,其方法流程简单,结果准确、可靠。     

Utility of solid phase spectrophotometry for the modified determination of trace amounts of cadmium in food samples

A modified selective, highly sensitive and accurate procedure for the determination of trace amounts of cadmium which reacts with 1-(2-benzothiazolylazo)-2-hydroxy-3-naphthoic acid (BTAHNA) to give a deep violet complex with high molar absorptivity (7.05 × 10⁶ L mol⁻¹ cm⁻¹, 3.92 × 10⁷ L mol⁻¹ cm⁻¹, 1.78 × 10⁸ L mol⁻¹ cm⁻¹, and 4.10 × 10⁸ L mol⁻¹ cm⁻¹), fixed on a Dowex 1-X8 type anion-exchange resin for 10 mL, 100 mL, 500 mL, and 1000 mL, respectively. Calibration is linear over the range 0.2-3.5 μg L⁻¹ with RSD of ?1.14% (n = 10). The detection and quantification limits were calculated. Increasing the sample volume can enhance the sensitivity. The method has been successfully applied for the determination of Cd(II) in food samples, water samples and some salts samples without interfering effect of various cations and anions.     

活性炭吸附原子吸收光度法测定铅锑精矿中金的含量

通过在铅锑精矿焙烧时加入一定量的氧化锌或氧化钙，使铅锑精矿在灼烧过程中的单质硫、有机质、硫化物、碳充分焙烧，然后采用王水分解矿样，活性炭动态吸附富集金，灰化除碳，王水溶解，原子吸收光度法测定铅锑精矿中金含量，方法快速、准确，同时适用于含碳、硫较高焙烧时易结块的精矿样品。     

Column solid‐phase extraction of sunset yellow and spectrophotometric determination of its use in powdered beverage and confectionery products

A new and simple solid‐phase extraction method for the determination of trace levels of sunset yellow has been developed on Diaion HP 2MG column system. The adsorbed sunset yellow on the resin was eluted with 3 mL of methanol and determined by UV–Vis spectrophotometry at 484 nm. Various experimental parameters such as pH, amount of sunset yellow, flow rates of sample and eluent solutions, resin amount, sample volumes, etc. were investigated. The influences of some alkali, alkali earth and transition metals on the recoveries of sunset yellow were investigated. The recovery values for sunset yellow were higher than 95%. Preconcentration factor was found as 150. The detection limit (three sigma) of the reagent blank for sunset yellow was 5.2 μg L^?1. The relative standard deviations (RSD) of the procedure were found as 3.9%. The validation of the presented procedure was performed by the method of standard addition. The procedure was successfully applied to the determination of trace levels of sunset yellow in powdered beverage and confectionery products.     

Cloud Point Extraction and Spectrophotometric Determination of Sulfide in Water Samples using Ethylene Blue Formation Reaction

Abstract

A rapid, selective, and sensitive cloud point extraction process using mixed micelle of a nonionic surfactant, Triton X-114, and an anionic surfactant, SDS, to extract sulfide from aqueous solutions was investigated. The method is based on the color reaction of sulfide with N,N-diethyl-p-phenylenediamine (DPD) in the presence of suitable oxidizing reagent (Fe³⁺) in acid media and cloud point extraction of ethylene blue (EB) dye. Various factors and optimal extraction and reaction conditions like: acid, Fe³⁺, reagent, and surfactant concentration were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, RSD%) were obtained. Linearity was obeyed in the range of 1–100 ng mL^?1 of sulfide ion. The detection limit of the method is 0.5 ng mL^?1 of sulfide ion. The interference effect of some anions, cations, and neutral species was also tested. The method was applied to the determination of sulfide in spring, river, and waste water samples.