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1.
《Analytical letters》2012,45(12):879-883
Abstract In the determination of fluoride ion with a fluoride ion-selective electrode, tiron is the most effective of masking agents tested for aluminum. The higher the pH, the more effective the masking, but the hydroxide ion raises the lower limit of determinable fluoride ion concentration at higher pH. Therefore, measurements at pH 6.0 are preferable. Fluorine in two glass samples has been successfully determined with tiron. 相似文献
2.
微波消解-氟离子选择电极法测定树叶中氟离子含量 总被引:1,自引:0,他引:1
采用微波消解处理样品,氟离子选择电极法测定了树叶中氟离子含量;通过正交实验考察了微波功率、消解时间、固液比、冷却时间等条件对微波消解的影响,对消解试剂和微波消解条件进行了筛选和优化。结果表明,其相对标准偏差小于0.46%,加标回收率在95.5%~103.3%之间。该法简单快速、准确可靠,对测定植物树叶中氟离子含量十分有效。 相似文献
3.
《Analytical letters》2012,45(6):451-465
Abstract The influence of the composition of buffer solutions on fluoride analyses by the fluoride ion selective electrode was studied. Residual fluoride content of reagents was observed to restrict the use of some buffers and reagents in low-level work. The optimum pH for low-level fluoride determinations was found to be around 5, which can be maintained by a sodium acetate-acetic acid buffer. Of the complexing agents studied, citrate was observed to be the most efficient masking agent for aluminum, but this ability depended strongly on ligand concentration. Citrate was also effective in masking iron (III) and magnesium ions. Tris (hydroxymethyi) aminomethane showed a similar ability to complex aluminum at a pH around 8. However, at this pH the hydroxyde ion interferes in fluoride analysis below 0.1 ppm [fbar]. 相似文献
4.
氟离子选择性电极法测定钍氟各级稳定常数 总被引:1,自引:0,他引:1
硫酸体系钍氟各级稳定常数对稀土冶炼生产实践具有重要的指导作用.采用溶解度法测定了室温(25 ℃)下不同酸度的钍氟共存区,采用氟离子选择电极测定不同浓度氟化氢溶液中的游离氟浓度,得到氢氟各级稳定常数.然后根据钍氟共存区图,配制一系列硫酸钍、氢氟酸和硫酸的混合液,测定各溶液中的游离氟浓度,从而得到钍氟各级稳定常数.结果表明,H与F的第1,2级稳定常数分别为k1=664.4,k2=47.9,Th和F的第1,2,3级稳定常数分别为k16.27×105,k2=9.68×104,k3=5.36×104. 相似文献
5.
《Analytical letters》2012,45(6):393-398
Abstract A rapid method for the direct determination of fluoride, not requiring a prior separation of fluoride by distillation, is given. Fluoride results differing from the calculated up to approximately 5% were obtained on samples of Fluorite, Cryolite, Topaz, Chiolite and Matlockite. 相似文献
6.
《Analytical letters》2012,45(7):569-580
Abstract An analytical procedure for the determination of fluoride ion left in the acetic acid leach solution of the U. S. Customs method for fluorspar is presented. The technique described employs an Orion fluoride ion-selective electrode. A semilogarithmic plot of fluoride ion concentration versus millivolt response yields a linear calibration curve. The new procedure s shown to compare favorably with the Customs method in economy analysis time, accuracy and precision. 相似文献
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《Analytical letters》2012,45(5):819-829
ABSTRACT In this work, a critical study of the determination of fluoride in oral products with an ion selective electrode was performed. The influence of the type of fluorine compound in the sample as well as the practical factors involved in the analysis were investigated. Fluoride could be determined, directly, in samples where it is in the form of NaF or SnF2. However, in samples where it is as MFP (sodium monofluorophosphate) an acid treatment was needed for removal of fluoride from the PO4F2? ion. In both cases, problems were noted related to the continuous use of the electrode, caused by the adsorption of fluoride ions onto the electrode surface. This problem was solved by using of KOH and Al2(SO4)3 solutions. Good results were obtained for the analysis of real commercial samples. 相似文献
9.
《Analytical letters》2012,45(9):1811-1825
ABSTRACT Design of the fluoride ion-selective electrode (FISE) as the tubular detector used in the flow injection analysis (FIA) has been described. Among other things, this design makes it possible to use various internal contacts. The effect of pH on peak height and detection limit in the pH range from 2.8 to 8.0 has been examined. The effect of flow rate and sample injection volume on peak height and range of linear response has also been examined. The flow rates range from 0.56 mL/min to 4.05 mL/min, while the injection volumes are 100 and 200 μL. The optimum conditions are carrier solution (0.1 M KNO3 buffer pH 4 and 10-6 M NaF), flow rate 1.54 mL/min and sample injection volume 100 μL. Applicability of the FISE as the tubular detector in determination of Fe(III)-ions and AI(III)-ions by flow infection analysis has been examined at pH values of 2.8 and 3.4. 相似文献
10.
为快捷有效地测定复合肥中氟的含量,采用盐酸浸取过夜、盐酸超声、碱熔、纯水煮沸四种方法提取复合肥中的氟离子,用氟离子选择电极进行测定,全程加标回收;结果发现盐酸超声提取法测得值与碱熔提取法测定值非常接近,并且加标回收率为98.4%~104.2%,相对标准偏差为1.9%;则用盐酸超声提取法测定复合肥中的氟含量方法可靠,方便快速,能够满足复合肥中氟含量的测试要求。 相似文献
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《Analytical letters》2012,45(13-14):1387-1406
Abstract A potentiometric flow injection analysis system is described, enabling tap water and other fluoride-bearing matrices of low interferent level to be determined at the rate of 360 samples per hour using an electrode polished with slurried alumina. Important parameters, such as carrier stream composition, sample volume and detector cell design are discussed with respect to this system, Fluoride electrodes regenerated with silver fluoride and silver epoxy are evaluated in flow injection mode, both before and after polishing. 相似文献
13.
建立了氟离子选择性电极对食品添加剂硫酸钙中氟离子含量的测定方法,通过标准曲线法进行定量,线性相关系数为0.999 1,线性范围为0.2~3.0μg/mL,方法的相对标准偏差为3.2%,加标回收率为97.8%~102.0%,实验结果表明所建立的方法简单、快速、准确,适用于食品级硫酸钙中氟离子含量的测定。 相似文献
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《Analytical letters》2012,45(11):2191-2200
ABSTRACT A Furaltadone (FD) ion-selective PVC membrane electrode based on the ion-pair complex of FD with sodium tetraphenylborate was prepared with dioctyl phthalate as a plasticiser. The electrode exhibits a linear response with an approximate Nernstian slope (50 mV decade?1 at 20 0C) with the concentration range 2.18 x 10?5–2.18 x 10?4 FD. The effects of ionic strength and pH of the test solution on the electrode performance were studied. The electrode exhibited very good selectivity for FD with respect to a large number of inorganic and organic cations of biological importance. The standard addition method and potentiometric titration were used to determine the FD in pure solution and in pharmaceutical preparations with satisfactory results. 相似文献
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《Analytical letters》2012,45(6):1081-1095
Abstract A simple potentiometric method is described for mercurimetric titration of barbiturates using a solid-state iodide ion-selective electrode. The optimum titration conditions involve the use of a borate buffer of pH 9–10 as a medium and mercury(II) perchlorate of pH 1.7–1.9 as a titrant. Under these conditions, titration curves with two sharp consecutive inflection breaks are obtained. The first inflection corresponds to quantitative and stoichiometric reaction of barbiturates with mercury(II) and the second break is due to the reaction of the buffer with the titrant. No interferences are caused by Cl?, Br?, PO4 3- and many excipients and diluents commonly used in the drug formulations. Determination of barbiturates in various pharmaceutical preparations gives reproducible results with an average recovery of 99.1% of the nominal (st.dev. 0.3 %) and the method offers significant advantages over the titrimetric method of the British Pharmacopoeia. 相似文献
18.
离子选择性电极电位法测定钼矿石和钨矿石中氟 总被引:2,自引:0,他引:2
采用过氧化钠熔融钼矿石、钨矿石样品,乙二胺四乙酸钠和5-磺基水杨酸混合溶液浸取盐分,将样品溶液静置12h,吸取上层清液,以乙二胺四乙酸钠-硝酸钾组成的混合溶液作为总离子强度缓冲剂,控制溶液pH值为5.1,使用pF-1型氟离子选择电极,以饱和甘汞电极作参比电极测定溶液的平衡电位值。采用标准曲线法测定钼矿石和钨矿石中氟。钼矿石标准物质测定值的相对标准偏差(n=11)为3.36%,经4种国家一级钼矿石、钨矿石标准物质的分析验证,测定结果与标准值吻合。 相似文献
19.
A method was developed for determining selenium with a self-made ion-selective electrode was developed. This electrode was
made by using Ag2Se as electroactive material. Optimal working conditions and interferences were investigated. The electrode exhibits good
potentiometric response for Se2− ions over the concentration range from 6 × 10−7 mol · L−1 to 1 × 10−4 mol · L−1 with a Nernstian slope of 28 ± 1 mV per decade and a detection limit of about 4.5 × 10−7 mol · L−1. It was used over six months and exhibits good selectivity and sensitivity towards Se2−. The method was applied to determine selenium in biological materials. The recovery ranges between 92% and 105.5%, and the
relative standard derivation is less than 3.6% (n = 6). 相似文献
20.
《Analytical letters》2012,45(7):425-435
Abstract An analysis of the potentiometric titration curves for the silver-cyanide system indicates two possible approaches to the determination of cyanide ion at low levels. Both involve an indirect measurement of the silver ion in equilibrium with argentocyanide complex. These procedures are considerably more sensitive than the conventional method using a “silver iodide” cyanide responsive electrode. 相似文献