固体石蜡碳糊电极示波滴定法

１引言示波滴定法是近十几年在我国迅速发展起来的一种电滴定分析方法．由于示波滴定法既具有指示剂法终点直观、测定方便的优点，又具有仪器法不受溶液颜色、沉淀的干扰，指示灵敏度高的优点，所以受到人们普遍的关注。随着示波滴定法的深入研究和广泛应用，已出现了一系列新的滴定法，如微铂电极示波计时电位滴定法，双金属电极示波电位滴定法等。作者首次提出固体石蜡碳糊电极（ＰＣＥ）示波计时电位滴定法和示波电位滴定法。以ＰＣＥ电极代替经典方法中的乘膜电极，仪器线路不变，同样可以进行示波计时电位滴定，许多物质在示波图上可产…     

两点电位滴定法测定盐酸曲马多含量

1　引　　言盐酸曲马多是一种安全高效、无成隐性的新型镇痛药 ,目前我国药典还未收录。对其含量的测定 ,我国卫生部推荐用高效液相色谱法。作者根据盐酸曲马多药物中含有可电离卤素的特点 ,提出一种测定盐酸曲马多含量的新方法———两点电位滴定法。该法只需在滴定计量点前附近记录两次标准溶液体积和相应电极电位值 ,利用公式计算滴定计量点 ,即可确定盐酸曲马多含量。方法简便易行 ,测定结果与传统电位滴定法一致 ,是一种测定盐酸曲马多含量的简便实用方法。2　实验部分2 1　仪器与试剂　ｐＨＳ 3Ａ数字型酸度计 (厦门第二分析仪器厂 )…     

用紫外分光光度法和电位滴定法测定几种植物激素的电离常数

分别采用紫外分光光度法和电位滴定法测定了脱落酸、3-吲哚乙酸、赤霉素、水杨酸等几种植物激素的电离常数,对比分析了两种测试方法的原理、测试步骤和数据处理方法.结果表明,采用两种方法测定的四种样品的电离常数与文献报道值一致,且测量结果的重现性较好;这表明紫外分光光度法和电位滴定法可方便地用于测定有机化合物的电离常数.     

溶剂对螯合物稳定性的影响：镉（Ⅱ）—甘氨酸（苯丙氨酸）—乙醇／…

用ＰＨ－电位滴定法测定了３７℃、Ｉ＝０．１ｍｏｌ．ｄｍ＾－３（ＫＮＯ３）、乙醇／水混合溶剂中配合物Ｃｄ（Ａａ）ｎ（Ａａ－＝甘氨酸、苯丙氨酸，ｎ＝１，２的一、二级稳定常数ｌｇｋ１、ｌｇｋ２及配体Ａａ＾－的酸解离常数ｐｋ１、ｐｋ２。     

新制氢氧化镍活度积的测定与计算

本文用ｐＨ滴定法（电位滴定）测定了氢氧化镍（新制）的活度积（１．７×１０－１５）。应用溶液平衡的基本原理提出了一种计算氢氧化镍活度积的较准确的方法，对影响测定准确度的工作因素进行了分析。对活度积测定与计算的其它方法进行了讨论     

氧瓶燃烧离子色谱法测定氯化聚乙烯中氯含量

元素分析仪法是测定有机元素含量的现代分析技术,一次进样可以同时测定化合物中的C、H、N等元素的含量,在元素含量分析中发挥了重要作用,但该方法对卤族元素无法测定.氧瓶燃烧分解样品后用电位滴定法或称(容)量法测定有机卤素的含量,是有机卤素分析的经典方法.国家标准测定聚氯乙烯样品中的氯含量采用氧瓶燃烧分解电位滴定法[1].电位滴定法一次只能测定样品中一种卤离子,若多种离子同时存在会产生干扰,影响测定结果,且需要配制多种试剂,费时费力.有机样品或聚合物经氧瓶燃烧法分解后采用离子色谱法一次进样可以同时测定多种元素的含量而互不干扰[2],分析速度和灵敏度都优于传统方法.许多有机化合物或聚合物都含有卤素,离子色谱对卤素离子测定的灵敏度很高,氧瓶燃烧离子色谱法弥补了元素分析仪法的不足,是有机化合物或聚合物卤素含量分析较理想的方法.本实验以间氯苯甲酸元素分析标准样品为对照品,测定了氯化聚乙烯中的氯含量,取得满意结果.     

卷烟纸中CaCO3的定量方法比较及形貌表征研究

分别采用煅烧法、电位滴定法及络合滴定法定量测定3种卷烟纸中CaCO3的含量,发现煅烧温度和时间对煅烧法的测定结果影响很大,当煅烧温度为900 ℃,煅烧2 h时卷烟纸中的纤维可完全氧化分解;电位滴定法和络合滴定法的结果具有较高的稳定性,但卷烟纸中的金属氧化物和碳酸盐易给电位滴定法带来误差,络合滴定法通过遮蔽剂可消除杂质离子的影响,具有较高的准确性。对3种卷烟纸灰分的XPS分析结果表明,灰分中除CaO外,还含有C、Na2CO3、Na2SiO3、Na3PO4、CaSiO3、Ca3(PO4)2等物质;SEM分析结果表明CaCO3呈纺锤状微晶和团簇状体分布在纤维中。该研究结果提供了一种比较准确的定量测定纸张中CaCO3含量的方法。     

电导滴定法快速测定钾的含量

１引言测定钾的含量常用火焰光度法和四苯硼钠重量法，火焰光度法适用于微量分析，四苯硼钠重量法的测定周期长。电导滴定法用于测定一些可发生沉淀反应的离子时，具有快速简便的优点。本文采用四苯硼钠溶液滴定，电导滴定法测定高、中含量组分钾的含量，测定周期仅需１０ｍｉｎ，所用试剂量少，不受样品中水不溶物的干扰，适用于钾盐、卤水和复合肥中钾的测定。２实验部分２．１仪器和药品电导率的测定采用ＤＤＳ－１２Ａ型数字式电导率仪和２１６型电导电极。四苯硼钠（Ｎａ［Ｂ（６Ｈ５）４］）为分析纯试剂，配成水溶液后用基准ＫＣＩ标…     

Gran电位滴定法测定乳酸环丙沙星

介绍了乳酸环丙沙星测定的Gran电位滴定法。采用Gran线性函数进行电位滴定,经图解外推或线性回归处理求出计量点,可直接用于测定乳酸环丙沙星原料药的含量。该法用于多批原料药的测定,结果与药典法基本一致。     

碳糊电极电位滴定法和示波滴定法测苯骈三氮唑含量

苯骈三氮唑(简称BTA),是一种用途广泛的助剂,是工业循环冷却水及内燃机车冷却水的重要添加剂,还可用于铜及其合金的防锈处理等.目前对它的测定方法主要有重量法、紫外分光光度法、色谱法等,这些方法多易受样品性质限制,且不能同时兼顾常量和微量BTA的测定.本文分别以碳糊电极和毛细管碳糊电极(首次应用)作指示电极,替代传统的银电极和汞膜电极,在NaAc介质中以AgNO_3溶液为滴定剂,电位滴定法和示波滴定法测定了工业合成样品及内燃机车冷却水中的BTA含量.     

Isotachophoretic determination of herbicides prometryne, desmetryne, terbutryne and hydroxy-derivatives of atrazine and simazine in extracts of milk

A method is described for the determination of the triazine herbicides prometryne, desmetryne, terbutryne, OH-atrazine and OH-simazine in purified extracts of milk using analytical capillary isotachophoresis. The reproducibility of isotachophoretic analyses was 3.5% and the detection sensitivity reached 2 ng. Recovery of triazines from fortified samples of homogenized full milk (0.05 mg/L) was about 65%.     

Development of a molecularly imprinted polymer for prometryne clean‐up in the environment

Molecularly imprinted polymers (MIPs) are prepared on the surface of modified silica gel using prometryne as a template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as a crosslinker, and 2,2‐azobisisobutyronitrile as an initiator. The structure of the MIPs was characterized using SEM and FTIR spectroscopy. The selectivity of the MIPs for the template molecule prometryne was proven by adsorption experiments. Highly selective SPE cartridges of MIP particles were developed and an optimized prometryne procedure was developed for the enrichment and clean‐up of prometryne residues in water, soil, and wheat samples. The concentrations of prometryne in the samples were analyzed by HPLC. The average recoveries of prometryne spiked for water at 0.05～0.8 mg/L were 101.47–106.65% and the RSD was 2.63–4.71%. The average recoveries of prometryne spiked for soil at 0.05～0.8 mg/L were 87.34–94.91% with the RSD being 2.77–8.41%. The average recoveries of prometryne spiked for wheat plant at 0.2～2.0 mg/kg were 91.04–97.76% with the RSD being 6.53–10.69%. The method developed here can be regenerated and repeatedly used more than two dozen times.     

Determination of herbicide residues in soil in the presence of persistent organochlorine insecticides

Summary A rapid and reproducible gas-chromatographic method has been developed for determination of residues in soil of some widely used herbicides such as trifluralin, metribuzin, alachlor, acetochlor, metolachlor, pendimethalin, simazine, atrazine, prometryne, in the presence of persistent organochlorine insecticides (p,p-DDT, o,p-DDT, p,p-DDE, alpha-HCH, gamma-HCH, heptachlor). Determination of some herbicides by GC/ECD is difficult since their relative retention times on packed columns usually used for pesticide analysis are equal or close to those of some persistent organochlorine insecticides which can still be found almost everywhere, especially in cultivated soils. A 1.8 m column of 3% OV-225 + 5% SE-52 in a ratio of 1.4:0.9 gave good separation of all herbicides and insecticides mentioned. The influence of 6 solvents and solvent systems applied most frequently for soil extraction of pesticide residues on recovery of the compounds under study was examined. Acetonitrile was the most suitable extractant as it rendered highest residue recoveries and minimal amount of co-extractives. Residues of simazine, atrazine, and prometryne were determined in the same extracts by the use of NP-detector and a column of 5% Carbowax 20M. Recoveries of the compounds under study were in the interval of 86–103% without cleanup and 78–94% when cleanup was carriet out. The method can be used in pesticide monitoring of soil as it offers an opportunity for rapid determination of soil applied herbicides and persistent organochlorine insecticides which are some of the most common pollutants in cultivated soils.     

Development of ultrasound-assisted emulsification microextraction for the determination of triazine herbicides in environmental water samples by high-performance liquid chromatography

A simple, rapid, efficient, and environmentally friendly method for the determination of some triazine herbicides (simazine, atrazine, prometone, ametryn and prometryne) in water samples was developed by ultrasound-assisted emulsification microextraction (USAEME) coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD). The main parameters that affect the extraction efficiencies, such as the kind and volume of the extraction solvent, ultrasound emulsification time and salt addition, were investigated and optimized. Under the optimum conditions, the method was sensitive and showed a good linearity within a range of 0.5 to 200?ngm?L^?1 for simazine, atrazine, prometone, ametryn and prometryne, with the correlation coefficients (r) varying from 0.9993 to 0.9998. High enrichment factors were obtained ranging from 148 to 225. The limits of detection (LODs) were in the range between 0.06 and 0.1?ngm?L^?1 and the limits of quantification (LOQs) were in the range between 0.2 and 0.3?ngm?L^?1. The recoveries of the analytes from water samples at spiking levels of 5.0 and 50.0?ngm?L^?1 were ranged from 82.4% to 107.0%. The relative standard deviations (RSDs) varied from 3.0% to 4.6%. The results demonstrated that the USAEME-HPLC-DAD method was an ef?cient pretreatment and enrichment procedure for the determination of triazine pesticides in real water samples.     

In-situ ionic liquid-based microwave-assisted dispersive liquid–liquid microextraction of triazine herbicides

We report on the determination of the triazine herbicides ametryne, prometryne, terbuthylazine and terbutryn in water samples. The herbicides are extracted by in-situ ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction and then determined by high-performance liquid chromatography. This is a new method for extraction that has the advantages of requiring less volume of ionic liquid (IL) than other methods and at the same time is quite fast. The type and volume of IL, the type and volume of disperser, irradiation temperature, extraction time and salt concentration were optimized. Figures of merit include linear regression coefficients between 0.9992 and 0.9995, acceptable recoveries (88.4–114?%), relative standard deviations of 1.6–6.2?%, and limits of detection between 0.52 and 1.3?μg?L^?1.

Comparison of microwave-assisted extraction of triazines from soils using water and organic solvents as the extractants

Microwave-assisted extraction (MAE) for the separation of atrazine, simazine and prometryne from synthetic soil samples, using water and some organic solvents as the extractants, was studied in detail. The effects of the soil matrix, the soil moisture and the pH of the aqueous extraction system on the MAE efficiency were also studied. It was found that the three triazines could be efficiently extracted under the conditions of 100% magnetron power output (600 W), the first grade of pressure (from 0.1 MPa to 0.5 MPa), 30 ml solvent and 4 min microwave heating with water or organic solvents, except for prometryne with dichloromethane solvent for 1-4 g sandy loam sample. This interesting result was explained by triazines' solubility in water, their sorption properties in soils and the ability of the solvent to absorb microwave energy. Finally, evaluation of the extraction efficiency, as well as the treatment and determination of MAE extracts, suggested that water, as a cheap, safe and environmentally friendly solvent, can be a good alternative to organic solvents, used as the extractants for MAE of triazines from soils.     

Polarographic behaviour of some s-triazine herbicides and their determination by adsorptive stripping voltammetry at the hanging mercury drop electrode

The electrochemical behaviour of six triazine herbicides (atrazine, terbutylazine, desmetryne, prometryne, terbutryne and methoprotryne) was studied by fast scan differential pulse voltammetry (FSDPV) at a static mercury drop electrode and by constant potential coulometry. The adsorption of these compounds at the mercury electrode was employed for their determination by adsorptive stripping voltammetry (AdSV) in Britton-Robinson buffers. The detection limits calculated from regression analyses ranged between 0.1 and 0.9 g/l. Preconcentration (solid phase extraction on a C18 column) was used for the determination of very low contents in water samples. The recovery was 97–99.6%.     

自制PEG-20M固相微萃取装置分离分析蔬菜中残留扑草净

固相微萃取(solid-phase m icroextraction,简称SPME)是在固相萃取基础上发展起来的集采样、萃取、浓缩、进样于一体的新型萃取分离技术,具有操作简单、方便、快速,耗样量少,无需萃取溶剂,重复性好等特点[1],特别适用于现场分析,无需进一步处理。有关SPME方面的综述已有很多,这     

Determination of Herbicides in Natural Waters Using Solid Phase Microextraction (SPME) and Gas Chromatography Coupled with Flame Thermionic and Mass Spectrometric Detection

Abstract

This study develops a method for solid phase microextraction (SPME) of ten widespread herbicides from water. The selected herbicides belong to different chemical groups are EPTC, molinate, propachlor, trifluralin, atrazine, propazine, terbuthylazine, prometryne, alachlor. Their determination was carried out by gas chromatography with flame thermionic and mass spectrometric detection. To perform the SPME, two types of fibre have been assayed: Carbowax-divinylbenzene (CW-DVB) of 65 μm thickness and polydimethylsiloxane-divinylbenzene (PDMS-DVB) of 65 μm thickness. The main factors affecting the SPME process such as pH, ionic strength, methanol content, memory effect, stirring rate and adsorption-time profile were studied. The method was applied to spiked natural waters such as ground water, sea water, lake water and river water in a concentration range of 0.1 to 10 μg/L. Limits of detection with each of the detectors were determined to be 1 – 20 ng/L in PDMS-DVB and 2–20 ng/L CW-DVB fibres. The recoveries of herbicides compared to distilled water were in relatively high levels 78.3–127.3 % and the average r² values of the calibration curves were above 0.99 for all the analytes. The SPME conditions were finally optimized in order to obtain maximum sensitivity and samples were applied for the trace-level determination in river water samples originating from Ioannina region (Greece).     

Determination of phenylurea and triazine herbicides in milk by microwave assisted ionic liquid microextraction high-performance liquid chromatography

The determination of phenylurea and triazine herbicides in milk based on microwave assisted ionic liquid microextraction (MAILME) coupled with high-performance liquid chromatographic separation was described. The experimental parameters of the MAILE, including type and amount of ionic liquid, microwave extraction power, extraction time and salt concentration in sample, were evaluated by a univariate method and orthogonal screening. When 60 μL of [C₆MIM][PF₆] was used as extraction solvent the target compounds can be isolated from the 4 mL of milk. The MAILME is quick (7 min) and simple. The detection limits for isoproturon, monolinuron, linuron, propazine, prometryne, terbutryn and trietazine are 0.46, 0.78, 1.00, 1.21, 1.96, 0.84 and 1.28 μg L⁻¹, respectively. The proposed method was applied to the analysis of milk samples and the recoveries of the analytes ranged from 88.4 to 117.9% and relative standard deviations were lower than7.43%.