基于颜色二阶矩和直方图联合判定的镝铁中铁含量自动分析仪研制

镝铁合金中铁含量的检测方法通常以人工滴定为主,但这种方法存在耗时长、操作繁琐、人眼判断滴定终点差异性等问题。本文研制了一种以图像处理为基础的镝铁中铁含量自动分析仪,实现了样品前处理、滴定、终点判定等过程一体化与自动化,减少了人工操作。可同时进行五个样品试验,提高了滴定效率。采用CCD工业相机摄取溶液图像,实现化学反应过程中溶液颜色的自动化识别,运用颜色分量二阶矩阈值和像素点数量排除溶液颜色交替变化的干扰,并基于直方图对比得到相似度进行滴定终点的判定,能够有效、准确地实现化学反应过程中溶液颜色的自动化识别。使用参考值为19.47%-20.25%的镝铁合金样品进行试验,与手工滴定结果比对验证,精密度测量结果相对标准差在0.21%以内,正确度测量结果误差在0.15%以内,满足国标《镝铁合金化学分析方法第4部分：铁量的测定 重铬酸钾容量法》（GB/T26416.4—2010）的精度要求。     

马一嘉,罗冰虹,谭凯馨

硫在作物生长过程中必不可少的营养元素之一,主要参与作物生理代谢及生长发育。因此,土壤中硫的含量一直是人们关注的热点,快速准确的检测方法也成为人们研究土壤中硫的关键。在高温燃烧碘量法测定土壤硫含量中,碘酸钾溶液滴定亚硫酸时,对于低含量样品,滴定终点的判断较为困难。通过大量的试验,采用硫代硫酸钠滴定吸收器中反应后剩余的碘酸钾溶液,滴定终点由蓝色消失为无色。终点便于肉眼的观察,提高了分析结果的准确性和再现性;采用EXCEL中的LINEST函数回归标准物质滴定校准工作曲线,方法简便快速。通过国家一级标准物质的分析验证,方法准确度高、精密度好,适用于大批量土壤样品中低含量硫的测定。     

矿石中钍和稀土的连续络合滴定

EDTA连续络合滴定钍和稀土存在的主要问题是在滴定钍后调节pH 5—6滴定稀土时,由于生成了Th-EDTA-指示剂有色三元配合物,指示剂被封闭,使终点无法辨认。Pribil甚至认为用EDTA或CDTA连续滴定稀土是不可能的。为了解决此问题,本文选择了指示剂和有关络合滴定条件以及矿石中常量钍和稀土的草酸盐沉淀分离条件。试验结果表明:草酸盐沉淀最佳酸度是pH1.5—2.5,此时回收率最高,以二甲酚橙为指示剂滴定钍最佳酸度是pH1.8—2.2,此时终点敏锐,高达15倍的稀土;尚无干扰;在连续滴定稀土时,本文首次提出以钙萤素及PAR为混合指示剂,在pH5.0—5.2的条件下以铜盐反滴定至萤光消失的方法测定稀土总量。由于采用了萤光滴定,所以钍量高达75mg对稀土的滴定尚无干扰,终点变化比其它指示剂明显,从而解决了钍对指示剂的封闭问题。可用以测定独居石、钍石等矿石中钍和稀土。     

可见光光谱滴定法测定水中总硬度北大核心CSCD

提出了可见光光谱滴定法测定水中总硬度的方法。在整个滴定过程采用颜色真实测量体系替代人的感官判定,建立了光谱计量参数与试剂量的色变滴定曲线,用曲线上的突变峰标识滴定终点或结构变化点。可见光光谱滴定法可以克服感官滴定存在色评价条件不统一、操作人员个体生理条件不一致、无法量值溯源等困难,能实现测定的自动化。上述方法用于测定水质总硬度标准样品,结果显示测定值均在标准样品认定值的不确定度范围内。按照标准加入法对实际样品进行回收试验,回收率为99.7%~101%。分别采用可见光光谱滴定法和目视滴定法[即乙二胺四乙酸(EDTA)络合滴定法]测定8种水体样品的总硬度,配对t检验结果表明两种方法的测定结果无显著性差异。     

酸碱滴定中的敏锐指数

在常规滴定分析中,滴定终点的确定是依据等当点前后指示剂颜色的改变来实现的。     

铜合金中铜的快速测定

铜合金中铜的测定,常用电解法和碘量法。前者准确,但设备昂贵,测定周期长;后者简便,但精确度低,终点颜色随试样不同而异,难以判断。本文拟定了一个新的测定法即碘化钾抗坏血酸法。试样以盐酸-过氧化氢溶解,移取溶液后,加氟化铵掩蔽铁,同时控制pH约4.5,然后在适量碘化钾存在下,以淀粉指示终点,用抗坏血酸滴定。     

2-羟基萘甲醛苯甲酰腙衍生物对Al~(3+)的裸眼识别和荧光传感

设计合成了化合物4-羟基苯甲酰-(2-羟基萘甲醛)腙(L)探针,经金属离子识别研究发现探针L对Al~(3+)具有良好的荧光增强识别效果且不受其它金属离子的干扰,且识别过程中溶液的颜色发生了明显变化,可以实现Al~(3+)的可视法检测,核磁滴定、job-plot、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF)等实验结果显示,探针L与Al~(3+)以摩尔比2∶1的方式进行配位。通过对紫外滴定数据的非线性拟合分析,探针L与Al~(3+)的结合常数为1.3×10~4L/mol,最低检测限为3.71×10~(-6)L/mol。因此,该腙类衍生物作为Al~(3+)的荧光及比色探针,识别体系线性范围较宽,检测限低,在痕量Al~(3+)的检测方面具有潜在的应用价值。     

铷和铯含量的示波极谱滴定法测定

用了示波极谱滴定法测定硝酸盐样品中铷和铯的含量，回收率为９７７８％～１００３％，相对标准偏差均值为０２１％。该法以示波极谱图形突变来确定滴定终点，终点直观，不受溶液颜色、沉淀的影响，具有准、快、简、省的特点，有广泛的应用价值     

非终点滴定法与其应用

为了实现滴定分析的快速和自动化,本文借鉴以往研究的经验针对其不足[1~8],提出了一种新的分析方法,滴定中只要加二次标准液,将采集到的数据通过适当的数学计算,即可得到样品液的浓度,本法不需要已知反应常数、电极转换系数等,对中和度没有严格要求[9~11],故具有可操作性和实用性。本法不需要确定终点,不需要全过程滴定,为滴定分析的自动、快速化提供了充分的条件,特别适合冶金、环境、食品、药品的大批量快速分析和在线分析。根据该方法的原理即可开发出一种新的自动分析仪。     

振荡抽滤-pH计指示电位滴定法快速测定土壤样品中阳离子交换总量

为了提高土壤中阳离子交换量(CEC)分析效率及分析准确度,采用乙酸铵或氯化铵-乙酸铵溶液对土壤样品进行处理,并采用振荡交换、抽滤分离的方式进行离子交换、铵离子清洗.土壤饱和吸附的铵离子用甲醛-C aC l2溶液交换后,采用氢氧化钠溶液滴定,并用p H计准确指示滴定终点,由此测定C EC含量.选用5个国家一级有效态标准物...     

Determination of SLES in Personal Care Products by Colloid Titration with Light Reflection Measurements

The method of colloid titration with poly(diallyldimethylammonium) chloride has been improved to detect the endpoint with an off-vessel light reflectance sensor. The digital color sensor used measures light reflectance by means of light guides, with no immersion into the reaction solution. In such a method, the optical signal is free of disturbances caused by sticky flocs in the solution. The improved automatic titration set was applied for the determination of sodium laureth sulfate (SLES) in industrial batches and commercial personal care products. The sample color and opacity do not disturb the SLES quantification. When the SLES content lies in the range from 5% to 9%, the optimal sample weight is from 6 g to 3 g.     

基于稀土离子颜色特征识别的组分含量检测方法

针对稀土离子具有特征颜色的P507-RECL3萃取分离体系,给出一种基于稀土离子颜色特征识别的组分含量检测方法。首先,通过对稀土离子颜色特征随组分含量的不同而呈现不同变化的分析,表明稀土组分含量与其颜色特征之间存在一定关系。为定量描述组分含量与颜色特征之间的关系,提取H分量直方图作为其颜色特征,并计算其一阶矩统计值,使抽象的颜色特征数值化,最后,利用最小二乘法拟合组分含量与H分量一阶矩统计值之间的函数关系,建立了分段拟合模型,并对模型的有效性进行了验证。结果表明,在单一组分占主要含量时,相对误差能控制在2%以内,具有较高的检测精度,为稀土组分含量的在线检测提供一种新的途径。     

基于反射式光度传感器的自动光度滴定仪的研制及应用

研制了一种以颜色变化为滴定终点的自动光度滴定仪,仪器以光度传感器为核心,包括光度探头、滴定装置、AT89S52单片机、电磁阀、二极管和磁力搅拌器等部件。传感器采用开放设计,对溶液吸光度变化反应迅速。仪器用于红醋酸度的测定,所得结果与电位滴定分析法结果相符。     

模式识别辅助镧镍电极的设计

应用模式识别和人工神经网络方法将已知样本按目标（稀土系镍氢电池容量和循环寿命）分类识别建模，在此基础地若干样本，通过人工神经网络预报，电池容量和循环寿命都达到设计要求。     

基于主成分分析的彩色扫描仪光谱特性化

为了实现扫描仪在不同光源、不同观察者条件下准确获取颜色信息,最大程度的避免同色异谱现象,本文采用光谱的方法对扫描仪进行特性化处理,通过多项式回归和BP神经网络分别与主成分分析法结合,首先对检测样本的光谱反射率进行主成分分析,提取主成分与主成分系数,通过实验得到主成分系数与多项式回归、BP神经网络结构之间的转换模型,实现了扫描仪低维RGB信号对原始光谱反射率信息的重构,进而实现扫描仪的光谱特性化.实验结果表明,多项式项数为19项时,达到训练样本的均方根误差为1.7%,检测样本的均方根误差为1.9%.而包含15个隐层节点的单隐层BP神经网络结构为比较合理的网络结构,达到训练样本的均方根误差为1.3%,检测样本的均方根误差为1.5%.对彩色扫描仪的特征化处理,采用多项式回归法得到光谱特性化精度较低,采用BP神经网络模型能够实现更高的光谱特性化精度.     

An automatic falling drop system based on multicommutation process for photometric chlorine determination in bleach

In this work an automatic photometric procedure for the determination of chlorine in bleach samples employing N,N′-diethyl-p-phenylenediamine (DPD) as chromogenic reagent is described. The procedure was based on a falling drop system where the analyte (Cl₂) was collected by a DPD solution drop (50 μL) after its delivery from the sample bulk that was previously acidified. The flow system was designed based on the multicommutation process assembling a set of three-way solenoid valves, which under microcomputer control afforded facilities to handle sample and reagent solution in order to control analyte delivering and solution drop generation. The analyte volatilization was improved by coupling online a little heating device. The detection system comprised a green LED (515 nm) and a phototransistor. Aiming to prove the usefulness of the proposed procedure a set of bleach samples was analyzed. Comparing the results with those obtained with reference method no significant difference at 95% confidence level was observed. Other profitable features such as a linear response ranging from 15 up to 100 mg L⁻¹ Cl₂ (R = 0.999); a detection limit of 4.5 mg L⁻¹ Cl₂ estimated based on the 3σ criterion; a relative standard deviation of 2.5% (n = 10) using a typical bleach sample containing 25.0 mg L⁻¹ Cl₂; a consumption of 55 μg of DPD per determination; and a analytical frequency of 20 determinations per hour were also achieved.     

Computerized technique in organic microelemental analysis: Part IV: Automated determination of chlorine,bromine, and iodine in organic compounds

The automatic and computerized rapid microanalytical determination of chlorine, bromine, and iodine in organic and organometallic compounds is described. The method consists of combustion of the compound in a large diameter empty tube connected to a titration vessel. The combustion products are transferred from the end of the combustion tube to the titration vessel by means of an automatic reductive SO₂-containing wash. Automatic potentiometric titration with AgClO₄ to the preset endpoint potential, using a combination silver microelectrode, serves as the endpoint detection of the titration of halides. The entire analysis, including automatic preparation of the equipment for the next determination, is programmed in a 6-min cycle. The method is blank-free; the results are accurate. Standard deviations amount to: 0.05, 0.14, and 0.18% absolute for Cl, Br, and I, respectively.The analyzer is interfaced to a real-time, time-sharing computer along with electronic microbalances and other analyzers, as part of the microanalytical laboratory computer service. The results of the analyses are reported on CR-terminals and are stored on magnetic disk for further processing.     

Determination of the Concentrations of Metal Cations in Aqueous Solutions Using Proton NMR Spectral Area Integration of the EDTA Complexes

This paper introduces an alternative method to determine the concentrations of metal cations in aqueous solutions, using area integration of proton NMR spectra of EDTA (the disodium salt of ethylenediaminetetraacetic acid) metal complexes. Using this method, a certain volume of unknown metal cation solution is added to an excess amount of standard EDTA solution, and the ratio of the remaining free EDTA and the EDTA–metal complex in the solution can be calculated from the integration areas of the proton NMR spectra. Unlike the conventional complexometric titration, where indicators need to be used to determine the endpoint, this NMR method aims to provide a simple method to eliminate the need for using indicators. This method, when EDTA is used as the standard, is valid for determining the concentrations of nonparamagnetic transition and rare earth metal cations, and for the concentrations of group IIIA and IVA metal cations.