电位滴定法测定锡基合金中的铅

研究用305型铅离子选择性电极为指示电极,电位滴定法测定锡基合金中铅的新方法。在测定体系中加过量的EDTA标准溶液络合铅,再用硝酸铅标准溶液滴定过量的EDTA,电位突跃明显,用二级微商法确定滴定终点和计算终点时耗用滴定剂的体积,方法准确度高,结果稳定,操作简便。并对测定条件和干扰离子的掩蔽作了试验,对样品中加标回收率达99.95％～100.02％。     

矿石中铅锌快速络合滴定法

利用铅锌矿中铅生成复盐沉淀 ,用EDTA标准溶液滴定锌 ,然后溶解复盐沉淀 ,加入过量EDTA标准溶液 ,用硝酸铅标准溶液反滴定。利用本方法测定铅锌矿中铅、锌 ,其铅的检测范围为质量分数 0 .4%～ 2 5 % ,锌的检测范围为质量分数 >1 % ,能满足地质检验中的分析误差要求。     

交流示波极谱漓定法测定砷(Ⅴ)及其在炼焦气脱硫砷碱液中的应用

高鸿等用铅标准溶液作滴定剂进行示波极谱滴定,成功地测定了铬酸根,钼酸根,钨酸根和磷酸根等阴离子。我们尝试在微酸性溶液中用生成焦砷酸铅的反应,进行示波极谱滴定测定砷(V)。应用在炼焦气脱硫砷碱液中砷的测定亦得到满意的结果。实验部分试剂和仪器 0.1919N铅标准溶液,0.03274N砷标准溶液:分别采用硝酸铅和砷酸钠配制,用常规方     

锡青铜中锡锌铅的连续滴定

锡青铜中锡、锌、铅的测定,目前大都采用一份试液分别测定的方法。本文采用同一份称样,用络合滴定法直接连续测定锡、锌、铅三个元素。试样以盐酸、过氧化氢溶解,用硫脲掩蔽铜,抗坏血酸掩蔽铁,加入过量EDTA标准溶液,将锡、锌、铅全部定量络合。以六次甲基四胺调至pH5.5,以二甲酚橙、溴甲酚绿作指示剂,用硝酸铅标准溶液滴定过量EDTA。而后,加氟化铵使Sn-EDTA中释放出等摩尔的EDTA,用硝酸铅标准溶液滴定,其量为锡。然后,加亚铁氰化     

自动电位滴定法测定铁矿中水溶性氯化物

应用自动电位滴定法,在pH＞2的微酸性乙醇-水(4+1)溶液中,用0.002 mol·L-1硝酸银标准溶液为滴定剂,测定了铁矿石样品中水溶性氯化物.试样用水在95℃温度条件下浸取使其水溶性氯化物溶出,共存的硫化物的干扰采用在微碱性条件下加入过氧化氢并煮沸至无小气泡产生可予以消除,对试样的预处理方法,以及各项影响测定的参数(如溶液介质,被滴定液的酸度及温度,滴定速度及搅拌速度等)做了试验并予以优化.方法的检出限(S/N=3)为2.0μg,用标准加入法做了回收率试验,结果在99.9%～100.4%之间.     

电位滴定法同时标定硫酸高铈和硫酸亚铁铵溶液

采用电位滴定法同时标定硫酸高铈标准溶液和硫酸亚铁铵标准溶液。以草酸钠为基准物质,通过对电位滴定装置的改进,在被滴定溶液与盐桥之间增加了一个一端封有磺酸型离子膜、内部注入2mol.L-1硫酸溶液的玻璃管,用来阻隔盐桥与被滴定溶液间的物质交换。方法用于硫酸高铈和硫酸亚铁铵溶液的标定,测定值的相对偏差为0.55%,表明方法具有高精度。     

电位滴定法测定钾的改进

Prokopov曾介绍了钾的电位滴定法。Walter Selig使用氟硼酸根电极作指示电极,用四苯硼化钠电位滴定铊,获得了满意结果。我们采用氟硼酸根电极为指示电极,在醋酸-醋酸钠(pH≈5)的缓冲溶液中,加入过量的四苯硼化钠标准溶液以沉淀钾,然后用AgNO_3标准溶液直接返滴定剩余的四苯硼化钠。并对在H_3PO_4-KH_2PO_4溶液中钾的电位滴定进行了研究。此法与四苯硼化钾重量法,与容量法相比较,具有方法简单、快速,准     

自动电位滴定法测定铜精矿中高含量氯

使用无水碳酸钠-氧化锌混合熔剂焙烧半熔铜精矿样品,分离大量的基体元素,用沸水浸取半熔物,在乙醇-水溶液中用硝酸银标准溶液电位滴定测定试液中的氯量;利用氯与银发生化学反应生成氯化银沉淀的原理以及电位突跃判断滴定终点。方法操作简单快速,重现性好,适应性强,可准确测定铜精矿中高含量氯(0.10%~5.00%)。     

自动电位滴定法测定阿司匹林肠溶片中总羧酸和阿司匹林的含量

建立自动电位滴定法测定阿司匹林肠溶片中总羧酸和阿司匹林含量的方法。自动电位滴定法以p H突跃监测终点,直接取数片阿司匹林肠溶片用25 m L 60%中性乙醇溶解;用0.2 mol·L~(-1)氢氧化钠标准溶液滴定总羧酸的含量,该终点为终点1;终点1后继续加入2倍量以上氢氧化钠标准溶液,在搅拌下60℃水浴加热5min,迅速冷却至室温,用0.1 mol·L~(-1)的盐酸标准溶液返滴剩余氢氧化钠溶液测定阿司匹林的含量。方法用于阿司匹林肠溶片分析(n=5),羧酸和阿司匹林的平均加标回收率分别在100.3%~100.8%和99.62%~100.4%,RSD在0.47%~2.1%。该方法仪器简单,操作方便,实验结果准确,为2010年版中国药典阿司匹林肠溶片中阿司匹林含量测定的标准修订提供参考。     

小波变换在自动电位滴定仪测定铁矿石中铁含量的应用

应用计算机化的自动电位滴定仪分析了铁矿石中铁量,并采用小波变换法测定滴定终点。试样溶液中的三价铁直接用三氯化钛还原至二价,溶液中共存的二价铁和过量的三价钛在滴定中都被重铬酸钾标准溶液所氧化,但两者的等当点电位可明显地相互区别,不影响二价铁的滴定及其定量计算。用所提出的方法分析了铁矿石标准物质,测得的铁量与标准值相符。     

利用连续流动分析仪测定水溶肥料硝态氮的方法研究

探讨了利用连续流动分析仪测定水溶肥料中的硝态氮的方法。选择含腐植酸、有机、微量元素、大量元素等4类水溶肥料样品,采用水振荡浸提试样,利用连续流动分析仪对浸提液中硝态氮的含量进行测定,并与紫外分光光度计测定数据进行对比,探讨利用连续流动分析仪测定化学肥料中硝态氮含量可行性。结果表明,流动分析仪法的方法检出限为0.008 g/kg;加标回收率在93.2%~101%;测定结果的相对标准偏差在1.7%~8.3%;所得数据与紫外分光光度计测定结果对比分析,t检验结果表明两种方法无显著差异;两种方法测定数据之间拟合方程为y=0.9782x+0.0768,R²=0.9966。结果表明,连续流动分析仪测试速度快,试剂消耗量少,精密度和准确度满足要求,可用于水溶肥料硝态氮含量的分析测定。     

Determination of phosphorus in fertilizers by inductively coupled plasma atomic emission spectrometry

An inductively coupled plasma atomic emission spectrometry (ICP-AES) method was developed for the determination of phosphorus in fertilizers. Total phosphorus, direct extraction available phosphorus (EDTA), and water-soluble phosphorus, reported as phosphorus pentoxide (P205), in 15 Magruder check fertilizers were measured by ICP-AES, and the results were compared with those obtained by the AOAC official method. Five analytical wavelengths of phosphorus, 177.499, 178.287, 213.618, 214.914, and 253.565 nm, were tested for the determination of phosphorus in fertilizers, and their detection limits were obtained. Acid effects of perchloric acid and possible matrix effects of aluminum, calcium, magnesium, potassium, and sodium were negligible for phosphorus determination. Wavelength 213.618 nm was the best analytical wavelength for phosphorus determination by all 3 sample preparation methods for the selected Magruder fertilizers. The results demonstrated that the accuracy and precision of the ICP-AES method were comparable with those of the official methods.     

磷肥中有效磷的示波滴定

根据Ｐｂ２＋能与ＰＯ＿４￣（３－）定量形成沉淀，过量的Ｐｂ２＋在ＮａＣｌＯ３－六次甲基四胺底液示波图上有敏锐切口的性质，报告了磷肥中有效磷含量测定的示波滴定新方法。该法与通用方法相比较，具有操作简便、测定快速、终点直观的优点。     

水溶性高分子链中磺酸盐基团含量的电导滴定测定法

研究了N ,N ,N 三甲基十六烷基溴化铵 (CTAB)与丙烯酰胺 (AM) 2 丙烯酰胺基 2 甲基丙磺酸钠盐(NaAMPS)二元共聚物P(AM co NaAMPS)的复合作用 .在复合作用过程中 ,由于不断释放出高导电性的无机盐小离子 ,故随着表面活性剂的加入 ,聚电解质水溶液的电导率不断增大 .当采用较低浓度 (0 0 0 1mol·L- 1 )且使二者的离子等摩尔量发生复合作用时 ,体系的电导率会发生明显的转折 .利用电导率的这一转折性变化 ,建立起了复合作用电导滴定法测定共聚物P(AM co NaAMPS)分子链中磺酸盐单体NaAMPS含量的新方法 .与元素分析进行比较的结果表明 ,上述复合作用电导滴定法可作为测定水溶性大分子链中磺酸盐单体含量的方便而又准确的方法 ,而且预计还可用作为测定水溶性大分子链中其它离子性基团含量的简捷方法     

超声波溶样法快速测定磷酸二铵中的水溶性磷和有效磷

建立了超声波溶样快速测定磷酸二铵中的水溶性磷和有效磷的方法。采用正交试验法分析影响溶解效果的因素，确定了最佳的溶解条件。溶样时间从8－12h缩短到30min。该方法简便、快捷，与经典法对照，精密度和准确度无显著性差异。     

Ion chromatographic determination of phosphorus soluble in different extracting media in fertilizers

A new method based on ion chromatography (IC) was developed for the determination of phosphorus in fertilizers. Fertilizers were extracted with water, mineral acids, and 2% formic acid, 2% citric acid, and neutral ammonium citrate solutions according to European Regulation No. 2003/2003 of the European Parliament and the Council of October 13, 2003, or the Decree of the Italian Agriculture Minister of June 17, 2002; the extracts were analyzed by direct injection, after simple filtration, by IC on an IonPac AS19 (250 x 4 mm id) column, using a KOH (21-50-21 mM) gradient and suppressed conductivity detection. The calibration plot was linear over the range of 5-50 mg/L (r(2) of >0.999). The method was evaluated by comparison with a gravimetric method according to established norms. Associated uncertainty at the 95% confidence level was established as 0.47% for the determination of 3-46% P2O5 by IC. A good chromatographic separation of phosphorus forms such as phosphates and phosphites, and some other important anions like nitrates, chlorides, and sulfates present in many commercial fertilizers was also possible, with a linear response over the range of 5-50 mg/L. After a more complete validation, this IC determination of phosphorus could replace more tedious methods such as those using gravimetric determinations.     

Determination of nitrate in thorium,uranium and plutonium solutions

A potentiometric titration method and a conductometric titration method were standardized for the determination of nitrate in thorium, uranium and plutonium solutions in the range of 2–10 mg, and 15–30 mg, respectively, with a precision and accuracy of 2% in both cases. The results were compared with those of other methods like Devarda's alloy reduction method and volumetric titration method. The procedures standardized have been recommended for the determination of nitrate in heavy element solutions used for the preparation of oxide and mixed oxide microspheres by the sol-gel technique.     

Development of a pH titration method for the simultaneous determination of uranium,nitrate and free-acid in the feed solution of the sol-gel process of nuclear fuel fabrication

pH titration curves generated by slow addition of alkali to solutions containing varying concentrations of uranyl nitrate and nitric acid were studied using an autotitrator linked to a personal computer. A procedure with multiple choice of equations has been developed for the estimation of free acid, nitrate and uranium in pure uranyl nitrate solution by a single titration. The technique provides a simple single-step method with required accuracy and precision for the simultaneous estimation of the three quantities in the uranyl nitrate feed solution of the sol-gel process for making UO₃ microspheres. The relative standard deviations in the determination of uranium and nitrate were ±0.82% and ±1.52%, respectively, in 15 determinations.     

A collaborative study of four methods of assay of benzylpenicillin

The assay of benzylpenicillin by iodimetric titration, spectrophotometry with a mercury(II) chloride—imidazole reagent, titration with mercury(II) nitrate in acetate buffer solution, and titration with mercury(II) perchlorate in aqueous pyridine solution, was examined in four laboratories. The first two methods were applied to two samples (the third one being the reference sample), the mercury(II) nitrate titration to three, and the mercury(II) perchlorate method to two samples. The four methods gave very similar results, but the purity obtained with the mercury(II) perchlorate method was slightly lower, and this procedure is less desirable because pyridine is used as solvent. There were no great differences in the relative standard deviations of the four methods. The titration with mercury(II) nitrate is preferred because it is an absolute method.     

Application of the Iodide Ion-Selective Electrode in the Potentiometric Determination of Chloral Hydrate

Abstract

A simple and sensitive micro method for chloral hydrate determination based on oxidation with iodine in chloroform solution is described. The produced iodide ion in the extract is determined using the iodide ion-selective electrode by either a direct measurement, standard addition technique or potentiometric titration with standard silver nitrate solution. Samples containing 0.1 - 4.0 mg chloral hydrate are analyzed with an average recovery of 99-9% and standard deviation of 0.1%.