Determination of Boron Trifluoride in Boron Trifluoride Complex by Fluoride Ion Selective Electrode

A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain p H value was limited and hardly related to F-concentration and boric acid. It is better to control p H value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 ℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

Determination of Fluoride in Various Samples Using a Fluoride Selective Electrode

Fluoride is widespread in the environment, water, air, vegetation and Earth’s crust which can entre ground and surface water by natural process. Fluoride in minute quantities is essential component for human health and help in normal mineralization of bone and formation of dental enamel. The determination of fluoride in some species was performed by using fluoride ion-selective electrode by direct measurement and standard addition method. The concentration of fluoride ion was determined in drinking water (from different place at Kathmandu), toothpaste, various brand of tea and coffees. The range of fluoride concentration in water sample was 0.16 to 0.39 mg/l, tea and coffee samples were 0.011 to 0.084 mg/l and its value of toothpaste was 0.026 to 0.75 mg/l. The concentration of fluoride ion obtain from different sample was compared with the legitimate value given by the world health organization.

Chemically Modified Carbon Paste Electrode for Determination of Cesium Ion by Potentiometric Method

A new chemically modified carbon paste electrode for cesium(I) ion determination based on potassium zinc hexacyan-oferrate (PZHCF) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cs(I) ions over a wide concentration range from 1 × 10-6 to 1 × 10-1 mol·L-1 with a slope of 58 ± 0.5 mV·decade-1. It has a response time of about 35 s and can be used for a period of 3 months with good reproducibility. Detection limit obtained in the optimal conditions was 3 × 10-7 mol·L-1. The potentiometric response is independent of the pH of the solution in the pH range 4.0 - 8.0. The electrode possesses the advantages of low resistance, fast response over a variety of other cations. The proposed electrode is applied as a sensor for the determination of Cs(I) ion concentration in different samples solutions. The results showed a good correlation with the data obtained by atomic absorption spectrometric method.

DETERMINATION OF SERUM ALBUMIN USING A SILVER ION SELECTIVE ELECTRODE

In this paper is reported a new method of determining serum albumin with potentiometry. The silver ion selective electrode was used as working electrode and S. C. E as reference electrode. By controlling the ionic strength, PH and temperature constant, a good linear relationship was obtained between the cell potential and albumin concentration. This method .possessed characters-of operating simplicity, rapidity and directness. The samples could be detected directly and the results were in accordance with the values detected by classic K method.

Construction and Application of a PVC Membrane Enoxacin Ion-selective Electrode Based on a Needle-shaped Inner Reference Electrode

A PVC membrane enoxacin ion-selective electrode based on a needle-shaped inner reference electrode was prepared. A Ag/AgCl wire was used as the substrate of this electrode. It was previously coated with a thin sheet of urea-formaldehyde resin containing Cl - ions to form a needle-shaped inner reference electrode, then the inner reference electrode was coated with a thin sheet of a PVC membrane containing an enoxacin tetraphenylborate ion-pair complex. The influences of various ion-pair complexes, concentrations of the active components in the membrane and the plasticizers on the performance of the electrode were studied by orthogonal design. The linear response range of the electrode was 7.9×10 -5 -1.0×10 -2 mol/L. The detection limit was 2.0×10 -5 mol/L. The slope was 30.4 mV/decade(25 ℃). The electrode can be used for the potentiometric determination of enoxacin tablets directly. The average recovery was 100.4%, and the RSD was 0.9%. The results agreed with those determined by the method in Chinese Pharmacopoeia.

Iron-Selective Electrode Based on Phosphorylated Calix-6-Arene Derivative

The construction and performance characteristics of a novel Iron(III) membrane sensor based on (37-bis-[(diethoxy-thiophosphoryl)-oxy]-5,11,17,23,29,35-hexa-kis-(1,1-dimethylethyl)-calix[6]-arene-38,39,40,41,42-pentol) (A) were reported in this paper. The sensor was prepared by incorporating compound (A) into a plasticized polyvinyl chloride PVC membrane. The electrode reveals a Nernstian behavior over a wide iron ion concentration range (1.0 × 10-2 - 1.0 × 10-4 mol·L-1), and relatively low detection limit (1.0 × 10-5 mol·L-1). The potentiometric response was independent on the pH of the solution in the range of 4 - 7. The electrode showed a very short response time (<5 s). It exhibited very good selectivity relative to a wide variety of metal cations. Correlation of selectivity coefficient values with ionic radii of interferent cations was discussed. The proposed iron- ISE was applied for analysis of iron containing samples with comparison to a recommended spectrophotometric method.

土壤环境氟化物测定中的离子选择电极分析方法

本文使用离子选择电极法测定土壤样品中的氟化物。为提高测定结果的精确性,测定实验中需要使用总离子强度调节缓冲液。选取TISAB1和TISAB2两种常用缓冲液进行对比实验,结果表明TISAB1缓冲液的3次测定结果均在保证值规定范围内,可以更好地满足氟化物测定实验中提高测定精度的需要。金属离子干扰实验表明,在Al^(3+)浓度不超过10 mg/L、Fe^(3+)浓度不超过50 Mg/L、Ca^(2+)浓度不超过100 mg/L的情况下,3种金属离子不会对氟化物测定结果产生干扰。土壤水溶态氟化物的检出限为2.1μg,土壤全态氟化物的检出限为2.2μg,可以满足土壤环境氟化物测定要求。

碱解-离子选择电极法测定冰晶石总氟含量

针对目前冰晶石总氟含量常规测定耗时长、操作烦琐、过程物质存在毒害性和测试成本高等不足,提出了碱解-氟离子选择电极法实现快速准确测定冰晶石中的总氟含量。样品预处理过程中,在200℃下采用过量氢氧化钠在镍坩埚中碱解1 h,可将冰晶石中的氟完全转换为氟离子。溶液电位测量过程中,在样品溶液和氟离子标准溶液中加入TISABⅣ总离子强度调节缓冲溶液来消除Al^(3+)的干扰,同时在氟离子标准溶液中加入适量Na^(+)和Al^(3+)来保证样品溶液和标准溶液的总离子势和Na^(+)浓度一致。实验结果表明,该方法与传统化学分析法一致性良好,平均相对偏差为0.40%,最大绝对偏差为0.32%,且5次平行测量相对标准偏差小于0.50%,适用于冰晶石总氟含量的快速批量测定,亦可推广用于其他氟化物中总氟含量测定。

焦化厂蒸氨废水中氨氮快速检测方法的研究

蒸氨废水中存在较高浓度的S^(2-),严重影响离子选择性电极法测定结果的准确性,因此,焦化厂蒸氨废水中氨氮的检测一般采用纳氏试剂比色法,但该方法操作过程烦琐、测定时间长,分析结果滞后。鉴于此,研制了全固态铵离子选择性电极,通过向废水中加入适量的醋酸锌消除S^(2-)的干扰,进而建立一种适用于蒸氨废水中氨氮快速检测的电化学分析方法。调节水样的pH至4~7,加入适量的醋酸锌,测量铵离子选择性电极与Ag/AgCl参比电极间的电位差,通过标准曲线即可快速获得水样中氨氮的浓度。该方法对氨氮的检测线性范围为0.14~1400 mg/L,检出限为0.011 mg/L,相对标准偏差RSD为1.14%~3.02%,加标回收率为99.85%~104.18%。该方法操作简便,测定时间短,可快速分析焦化厂蒸氨废水中的氨氮,并具有开发氨氮在线监测装置的良好应用前景。

离子色谱法和离子选择电极法对氟化氢溶液中的氟化物分析对比

氟化物指含负价氟的有机或无机化合物。与其他卤素类似,氟生成单负阴离子。无机氟化物的例子有氢氟酸(HF)、氟化钠(NaF)等。本文用离子选择电极法和离子色谱法分别分析含氢氟酸(HF)溶液中的氟化物。发现溶液含有氢氟酸(HF)时分析氟化物,分析结果与p H值形成干扰,pH值越低氟化物的结果越高,而采用氢氧化钠将溶液中和成碱性条件和用碳酸钠-碳酸氢钠淋洗液体系稀释样品时,干扰最小。而含氢氟酸(HF)溶液采用离子选择电极法分析时溶液pH值偏低,H+偏高,会氟化物的浓度偏高,而溶液p H值调至中性条件时干扰最小,结果最接近真值。

离子选择电极法测定水中氟化物的不确定度评定

目的:采用离子选择电极法测定生活饮用水中氟化物的含量,评定测定过程中的不确定度分量。方法:依据标准《测量不确定度评定与表示》(JJF 1059.1—2012)和《化学分析中不确定度的评估指南》(CNAS-GL006:2019),分析不确定度来源,建立数学模型,对测定过程中的各不确定度分量进行分析和计算,综合评估氟化物含量的不确定度。结果:当生活饮用水中氟化物的含量为0.915 mg·L^(-1)时,其扩展不确定度为0.038 mg·L^(-1)(k=2),测定结果可表示为(0.915±0.038)mg·L^(-1)(k=2)。结论:影响检测结果不确定度的因素主要是标准系列溶液的配制,在实验中可以通过严格控制标准系列溶液的配制过程提高检测结果的准确性。

工业废水中氟离子测定方法比对

对GB/T 7484-1987《水质氟化物的测定离子选择电极法》和低含量氟的测定方法HJ 488-2009《水质氟化物氟试剂分光光度法》进行了方法验证,从样品保存、标准曲线线性、检出限、加标回收率、精密度、准确度、样品测定、方法对比等方面进行了条件试验研究。试验表明:氟试剂分光光度法适合水样洁净,无干扰项样品的测定,且操作繁琐、耗时较长;离子选择电极法测定范围较广,结果准确,能够快速指导生产,是一种既经济又准确的氟化物检测方法。

氟离子选择电极法测定土壤中水溶性氟化物和总氟化物含量

采用氟离子选择电极法测定土壤中水溶性氟化物和总氟化物。结果表明,氟化物含量在5~500μg范围内具有良好的线性关系(>0.999),水溶性氟化物方法检出限为0.5 mg/kg,相对标准偏差(RSD,n=6)为3.8%~6.7%,总氟化物方法检出限为43 mg/kg,相对标准偏差(RSD,n=6)为4.0%~4.2%,满足标准方法的测定要求。有证标准物质RMU044和RMU045测定结果均在标准范围内,水溶性氟化物相对误差为-3.3%~-2.4%,相对标准偏差为4.0%~4.7%,总氟化物相对误差为0.9%~1.3%,相对标准偏差为1.0%~2.2%。实际样品加标回收率试验时,水溶性氟化物平均加标回收率为100%,总氟化物的平均加标回收率为94%,该实验方法重现性好,准确度高,操作简单。

茶叶鲜叶氟含量调查分析

为探究茶叶鲜叶氟含量情况,本研究采集了不同叶位、生长阶段、季节和地区的茶叶鲜叶,经杀青烘干处理,采用沸水浴浸泡提取氟化物,选择电极法测定氟离子,通过数据比对和分析,探究了茶叶鲜叶氟含量、变化规律和影响因素。研究表明,不同叶位鲜叶的氟含量呈线性变化规律:新芽尖<第1叶<第2叶<第3叶<第4叶;不同叶龄鲜叶氟含量整体呈线性变化规律:1芽1叶<1芽2叶<1芽3叶<1芽4叶<1芽5叶。茶叶鲜叶嫩叶氟含量低于老叶氟含量;随着叶龄的增长,茶叶鲜叶氟含量呈现上升趋势。该研究为茶叶产业发展提供参考。

Solid-Contact Perchlorate Sensor with Nanomolar Detection Limit Based on Cobalt Phthalocyanine Ionophores Covalently Attached to Polyacrylamide

Novel solid-contact perchlorate sensors based on cobalt phthalocyanine-C-monocarboxylic acid (I), and cobalt phthalocyanine-C,C,C,C-tetracarboxylic acid (II) as free ionophores and covalently attached to polyacryla- mide (PAA)—ionophores III and IV, respectively were prepared. The all solid-state sensors were constructed by the application of a thin film of a polymer cocktail containing a phthalocyanine ionophore and cetyltrimethylammonium bromide (CTMAB) as a lipophilic cationic additive onto a gold electrode precoated with the conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) as an ion and electron transducer. The sensor with 10.3% of ionophore (III) covalently attached to plasticizer-free poly (butyl methacrylate-co-do- decyl methacrylate) (PBDA) exhibited a good selectivity for perchlorate and discriminated many ions, in- cluding F–, Cl–, Br–, I–, SCN–, , S2– and . The covalent attachment of the ionophore to the polymer resulted in a near-Nernstian anionic slope of –62.3 mV/decade whereas a super-Nernstian slope of –79.9 mV/ decade was obtained for the free ionophore. The sensor covered a linear concentration range of 5 × 10–9 - 1 × 10–2 mol?L–1 with a lower detection limit (LDL) of 1 × 10–9 mol?L–1 and gave a stable response over a pH range of 4 - 10.5. The all-solid state sensors were utilized for the selective flow injection potentiometric determination of perchlorate in natural water and human urine samples in the nanomolar concentration range.

ON-LINE DETERMINATION OF REMAINED XANTHATE CONCENTRATION IN PULP

The construction principle of the system for determination of xanthate concentration,which consists of an Ionselective electrode(ISE) and a microprocessor based SDI analyzer,was described in the paper.The performances of the developed system were discussed in details.The results both detected in solutions and in sulfide mineral flotation system were given; also the results by ultraviolet spectrometry were compared with those by the developed system.

碱熔-氟离子选择电极法测定煤中氟含量

氟离子选择电极法是常用的测定氟含量的方法,高温水解是目前标准中规定的测定煤中氟含量的前处理方法,但该前处理过程操作繁琐、费时,为了实现快速测定煤中氟含量,对前处理过程进行研究,利用碱熔融煤样,并与高温水解方法进行对比研究。通过研究碱熔法中样品量和氢氧化钠比例、灰化温度及时间、熔融温度和定量分析方法对煤中氟含量测定的影响,确定了碱熔法的实验条件,同时讨论了方法检出限、方法准确度、精密度和稳定性。结果表明,称取样品量0.5~1.0 g与6.0 g氢氧化钠混匀,灰化温度为400℃,熔融过程控制在600℃,10 min,然后用热水浸取,加柠檬酸钠溶液,以苯酚红为指示剂,调节溶液pH值,选用氟离子选择电极标准溶液加入法测定氟离子浓度。方法的检出限为8.5μg/g,具有良好的准确度、精密度和稳定性,而且操作简便、干扰少、能快速批量处理煤样,能够满足进出口煤炭的快速检测。

土壤和岩石矿物中氟元素分析测试技术研究进展

准确测定土壤和岩石矿物中氟元素含量,对于评估区域性地球化学行为和预防人类氟相关病症具有重要的意义。本文阐述了近年来土壤和岩石矿物中氟元素分析测试技术研究进展,重点对样品前处理方法、试剂和流程进行了归纳总结,对不同检测方法的基体校正、干扰控制、性能及应用现状等进行评述,分析了不同测试技术的特点与不足,展望了其未来发展方向。目前常用的前处理方法主要有粉末压片法、熔片法、水蒸气蒸馏法、高温燃烧水解法、碱熔法和酸溶法等,常用的测定方法主要有离子选择电极法、离子色谱法、X射线荧光光谱法(XRF)、分光光度法、比色法和液相色谱法等。其中碱熔-离子选择电极法和粉末压片XRF法经分析测试工作者不断探究和改进,已是土壤和岩石矿物中氟元素分析广泛应用的测试技术。但碱熔法存在试剂消耗量大、流程长,步骤繁琐以及阳离子干扰等缺点,优化测试技术方法还需要进一步研究和实践;粉末压片法为无损进样,简单快速环保,具有潜在的研究价值,使用XRF法能够实现多元素联测,在稳定性和精密度方面具有显著的优势,降低方法检出限、消除粒度效应和矿物效应将是未来XRF法测定氟的研究趋势之一;其他前处理方法因步骤繁琐、前处理设备昂贵以及只能处理特定类型样品等因素的制约,或因测试方法的局限性制约其发展,暂不作推荐。由于氟属于轻元素以及赋存形式复杂多样等特殊性,需要针对样品类型的特点选择相适应的分析测试技术。本文认为,对于土壤和岩石矿物中氟含量分析测试技术,样品无损分析、安全环保、快速等是前处理方法研究的主要方向,同时能够建立多元素联测、检出限低以及稳定性好的测试方法是测试技术研究的主要方向,综合来说粉末压片-XRF法测定土壤和岩石矿物中氟具有重要的研究价值。

氟离子选择电极法测定植物性食品基质中的氟化物

建立了植物性食品中氟化物的氟离子选择电极测定法,并对不同基质中氟化物含量进行了测定。对GB/T 5009.18—2003第三法(氟离子选择电极法)中标准曲线的线性范围和不同基质的称样量范围进行了优化,确定了方法的定量限,并对准确度、精密度进行了验证。结果表明:本方法在0.20~10.00 mg/L范围内线性良好,方程的斜率及相关系数均符合测定要求;称样量范围优化为2.5~5.0 g(茶叶基质0.2~0.5 g),平均加标回收率为99.97%~109.83%,相对标准偏差为0.41%~2.65%,均符合国家标准要求;除茶叶以外的基质,当称样量为2.5 g,定容体积为50 mL时,方法定量限为4.00 mg/kg;对于茶叶基质,当称样量为0.2 g,定容体积为50 mL时,方法定量限为50.00 mg/kg。该氟离子选择电极法适用于植物性食品基质中氟化物的快速检测。

氟离子选择性电极法测定茶叶中的氟含量

离子选择性电极法是测定茶叶中氟离子含量较为常用的方法,但是不同前处理浸提方法的相对浸提效果并不是很明确。通过对酸、碱、超声和热水四种不同的浸提方法进行比较,探究茶叶中氟离子浸出的最佳方法。实验结果表明:热水浸提的氟离子浸出量最高,达到了111.4μg·g^(-1)。热水浸提的最佳条件是60℃下浸提30 min,适合批量茶叶中氟含量的测定。