氢化物发生-原子荧光光谱法测定钨矿石、钼矿石中锑

采用HNO3-HF-H2SO4分解钨矿石,钼矿石,柠檬酸-KI溶液掩蔽干扰,加入硫脲-抗坏血酸溶液还原后,应用氢化物发生-原子荧光光谱法测量溶液中Sb含量。通过优化仪器测定条件和酸度,配合柠檬酸和KI的使用有效地避免了干扰。方法检出限为4 ng/g,RSD为3.9%~8.3%,回收率为90%~106%。经8家实验室对钨钼矿石标准物质样品精密度、准确度验证,精密度满足要求,且方法偏倚不显著。方法可用于钨矿石、钼矿石中Sb的测定。     

电感耦合等离子体原子发射光谱法测定钨矿石中硅、铁、铝、钛、钨、锡和钼的含量

采用过氧化钠-氢氧化钠混合试剂熔融钨矿石样品,用酒石酸-盐酸体系酸化提取制备样品溶液,采用电感耦合等离子体原子发射光谱法测定样品溶液中上述7种元素的含量。选择硅、铁、铝、钛、钨、钼和锡的分析谱线分别为251.61,259.94,396.15,334.94,239.71,202.03,189.98nm。7种组分在一定的质量浓度范围内与其对应元素的光谱强度呈线性关系,方法的检出限(3s)在0.000 24~0.063 mg·g-1之间。方法应用于钨矿石标准物质(GBW 07240,GBW07241)的分析,测定值与认定值相符,测定值的相对标准偏差(n=12)在0.48%~5.1%之间。     

标准加入法数据处理的改进及用于测定宜昌茶叶的氟含量

利用氟离子选择电极,采用一种改进的标准加入法的数据处理方法测定湖北宜昌几种茶叶中的氟含量.与传统的标准加入法不同的是:以加入标准溶液后测得溶液中待测物质(如:氟离子)的总质量(样品及加入标准液后氟离子的质量之和)对加入标准液的中该物质的质量(标准液中氟离子的质量)作图.湖北宜昌某品牌茶叶中的氟含量为46.8±0.5 mg/kg,相对标准偏差(RSD)为0.79%,加标回收率在98.0%～102.5%之间.改进后的标准加入法的数据处理方法简单、快速,能够提供更多的信息(如:加标回收率).     

离子选择性电极非线性测定水中氟离子的含量

利用氟离子选择性电极测定系列氟离子标准溶液的电极电位(vs.SCE),用测得的电极电位值与氟离子标准溶液的浓度数据进行非线性工作曲线拟舍,可准确测定1×10~(-6)～1×10~(-5)moL/L氟离子溶液的浓度。该法易于实现氟离子溶液的自动连续监测,适于氟离子溶液浓度的在线测量。     

氟喹诺酮混合溶液标准物质研制

建立甲醇中8种氟喹诺酮药物混合溶液标准物质的制备方法。采用重量-容量法配制混合溶液标准物质,以配制值作为标准物质的特性量值,考察不同氟喹诺酮药物之间互为杂质情况,采用高效液相色谱法对标准物质进行均匀性和稳定性检验,并对制备过程产生的不确定度进行评定。研制的甲醇中8种氟喹诺酮药物混合溶液标准物质具有良好的均匀性和稳定性,其质量浓度均为100 mg/L,相对扩展不确定度为2%~3%(k=2),已被批准为国家二级标准物质,编号为GBW(E)083598。该混合溶液标准物质可为农产品质量安全监测与风险评估中氟喹诺酮类药物残留测定提供溯源保障。     

碱熔-离子交换树脂分离-电感耦合等离子体原子发射光谱法测定钨钼矿石中的钨、钼、硼、硫和磷

称取0.500 0g样品置于镍坩埚中,加入2.5g氢氧化钠,再覆盖0.5g过氧化钠,盖好坩埚盖,置于马弗炉中,升温至700℃并保持7min,取出冷却,用50mL热水溶解熔融物,将溶液转移至100mL塑料容量瓶中,用水定容,摇匀后静置。移取10mL上清液,加入5mL已处理好的732树脂溶液,振荡20min,用水定容至20mL,再振荡10min,离心,上清液供电感耦合等离子体原子发射光谱分析。选择B 249.772nm,W 207.912nm,Mo 203.846nm,P 213.618nm,S181.972nm为分析线。钨、钼、硼、硫和磷的质量浓度在一定范围内与其发射强度呈线性关系,检出限(3s)分别为15,11,6,34,23μg·g-1。方法用于测定钨钼矿石国家一级标准物质中的钨、钼、硼、硫和磷,测定值与认定值的相对偏差在-3.2%~2.0%之间,测定值的相对标准偏差(n=11)小于3.0%。方法用于同时测定钨钼矿石样品中的钨、钼、硼、硫和磷,结果与采用传统方法分别测定上述5种元素的结果相符。     

氟离子选择电极法测定骨中氟含量

骨中氟含量的测定通常采用较烦琐费时的扩散-比色法。氟离子选择电极的创建是氟化物分析方法的重大发展。Singer等曾应用氟电极测定骨中氟,方法快速而准确,但其操作需要用稀酸碱及醋酸盐小心调节骨样溶液以使其与标准氟溶液具有同一离子强度及pH值。我们采用TISAB技术,以自制Y-1型氟电极测定骨中氟含量,较Singer等所提出的方法更为简便与快速。实验部分 (一)仪器氟电极:自制Y-1型氟离子选择电     

非平衡态-恒电位配位滴定法同时测定铁和铝

以氟离子溶液作滴定剂，氟离子选择性电极作指示电极，在氟-铝反应没有达到平衡条件下通过恒电位配位滴定法同时测定了铁和铝。控制溶液的pH值为1．5，温度为25℃，硝酸钠离子强度调节剂浓度为0．1mol／L，反应时间为60s。在氟-铁反应达到平衡，但在氟-铝反应没有达到平衡的条件下，采集滴定数据。根据非平衡条件下，响应值的重现性，利用最小二乘法求出常数kFe、kAl及k0，进而计算出铁和铝的浓度。     

电感耦合等离子体发射质谱法测定钨矿石中的钨华

建立电感耦合等离子体发射质谱法测定钨矿石中钨华的含量。用氨水溶液对矿石样品进行浸取分离,将浸取液稀释10倍体积后测定,以3%盐酸溶液作为测定介质。WO3的质量浓度在0~100 ng/m L范围内与信号强度呈良好的线性关系,相关系数为0.999 9,方法检出限为0.5 ng/m L。用该方法对5个钨矿石样品和2个标准物质样品中的钨华进行测定,测定结果的相对标准偏差为2.15%~9.46%(n=12),且与经典方法极谱法测定结果的相对偏差小于10%。该方法快速、简便,精确度较高,可用于钨矿石中钨华的测定。     

氧弹燃烧-离子选择性电极法测定氟

介绍了一种测定试样中氟含量的快速方法。首先利用氧弹燃烧技术对样品进行预处理,将氟转化为氟化氢,用碱液吸收燃烧产物,吸收液加入TISAB消除Al^3 、Fe^3 等离子干扰,调节溶液pH在5～8后进行定容,然后用氟离子选择性电极用标准加入法测定溶液的电位,从而测得样品中氟的含量。对香烟、头发和饲料进行分析,结果表明该法简单、快速、结果可靠,可用于试样中氟的快速测定     

Highly Selective Fluoride Recognition by a Simple Carbazole-based Hydrozone Derivative

A simple carbazole hydrozone derivative(1) was synthesized and used as an optical probe for fluoride recognition in CH₃CN. Receptor 1 exhibited colorimetric and fluorescent dual-channel response to fluoride anions. Addition of fluoride to a receptor 1 solution in CH₃CN induced a distinct color change from yellow to magenta, the solution also displayed significant fluorescence blue shift. Thus receptor 1 exhibited dual-channel responses to fluoride with a high selectivity and sensitivity.     

Determination of Total and Fluoride Bound Aluminium in Tea Infusions by Ion Selective Electrode and Flame Atomic Absorption Spectrometry

ABSTRACT

Speciation of metallic compunds is important especially for their bioavailability. In this present study fluoride bound aluminium species were determined in tea infusion. Total aluminium was measured using flame atomic absorption spectrometry (FAAS). Free fluoride and total fluoride were measured by fluoride selective ion electrode (FISE) with the assistance of TISAB buffer solution used for adjustment of pH and total ionic strength, and ALCOA buffer solution which decomposes all of the Al-fluoride complexes in solution.

During the studies, the effects of pH and time on the formation of Al-F complexes and interference of some metal ions found in tea infusion such as Al³⁺, Mg²⁺, Fe²⁺, Fe³⁺ and Mn²⁺ on the concentration of free fluoride were investigated. The concentration of each Al-fluoride complexes in tea fusion were determined indirectly by calculation using pF-Mole Fraction Diagram. It was found that 1.13±0.15 mg 1^? of 12.00±0.86 mg 1^? total aluminium is fluoride bound aluminium, which means that appoximately 10% of total aluminium in tea infusion is complexed with fluoride.     

The Analysis of Fluoride in Geothermal-Geopressured Brines

Abstract

Fluoride ion was determined by means of a fluoride ion selective electrode on geothermal-geopressured brines obtained from the DOW-DOE L. R. Sweezy ^#1 Well. The values decrease from 7.8ppm to a plateau value of 1.6–1.8 ppm.     

Fluoride adsorption enhancement of Calcined-Kaolin/Hydroxyapatite composite

The use of waste or natural resources is an interesting approach to preparing adsorbent materials. Most adsorption materials are powder-based, making them impractical for a variety of applications. In this work, the natural kaolin clay and hydroxyapatite synthesized from biogenic waste were studied as defluoridation materials. The point of zero charge (pH_PZC), the fluoride adsorption capability and the adsorption isotherm of calcined kaolin and mixed calcined kaolin/hydroxyapatite in both powdered and moulded forms were investigated. The hardness of the moulded (post-formed) samples was tested before and after in immersion in a fluoride solution. The maximum hardness was 15.8 kilo-pounds for the post-formed calcined kaolin sample. Sample hardness values slightly decreased after immersion in a fluoride solution due to the formation of micro-cracks. Most samples presented high pH_PZC values, implying that these materials are suitable for the capture of fluoride anions. The adsorption properties varied with the ratio of calcined kaolin to hydroxyapatite. These properties for post-formed samples were different from those in powdered form. Post-formed samples showed higher fluoride adsorption. The maximum fluoride adsorption capacity and efficiency of the post-formed samples (calcined kaolin) at pH 3 were 1.74 F^? mg/g and 87%, respectively. The sorption of fluoride of hydroxyapatite and mixed calcined kaolin/hydroxyapatite powders was found to have the form of the Langmuir isotherm, which indicates a monolayer adsorption on the adsorbent surface. Isotherms of calcined kaolin powder, post-formed calcined kaolin and mixed calcined kaolin/hydroxyapatite samples followed the Freundlich isotherm, which indicates multilayer adsorption on a heterogenous adsorbent surface.     

Indirect Spectrophotometric Determination of Fluoride In Water With Zirconium-Spadns By Flow Injection Analysis

Abstract

The zirconium-SPADNS method for the determination of fluoride based on the effect of fluoride ion on the color system (Zr-SPADNS), has been adapted to the continuous flow spectrophotometry. A manifold consisting of two lines was used. the decrease in the absorbance of Zr-SPADNS reagent at 590 nm is linear with fluoride concentration in the range 0.00-3.5 ppm. the method has a detection limit of 0.02 ppm fluoride. At a sampling rate of 50 determinations per hour, the precision was about 1% relative standard deviation. the method is applied to the determination of fluoride in natural water samples. the good agreement between the results obtained by this method and those obtained by a potentiometric method using a fluoride ion-selective electrode, show that the new method is potentially suitable for routine analysis. the effects of reaction conditions, flow parameters, and interferences on the FIA-spectrophotometric signals are reported. amount of interfering ion is present in quantity great enough to produce an error of 0.1 ppm or more, the sample must be distilled¹⁷     

Determination of Thorium and Total Rare Earths in Monazite Sand with Fluoride Electrode

A new method has been proposed to determine the total rare earths and thorium in monazite sand with fluoride electrode. The total amount of thorium and rare earths could be determined by back-titration with standard lanthanum solution in excess fluoride, and the rare earths were titrated directly with fluoride from separate sample. Fluoride electrode was used as indicator electrode. Precision and accuracy were improved by Gran's plot technique.     

Extraction-Spectrophotometric Determination of Fluoride Using N-Phenylbenzohydroxamic Acid

Abstract

Fluoride gives a very stable complex with scandium and, hence, by determining the unreacted scandium, the fluoride content can be calculated. Excess scandium is reacted with an ethanolic solution of N-benzoylphenylhydroxylamine (BPHA) at pH 6.0, and the scandium-BPHA complex is extracted into isoamyl alcohol. Scandium is determined spectrophotometrically after adding xylenol orange. Beer's law for fluoride is obeyed in the range of 0.05 –1.5 ppm; the molar absorptivity is 1.94×10⁴ 1 mol^?1 at 565 nm. The procedure is applicable for the determination of fluoride in various types of samples.     

离子选择电极法测定生活饮用水中氟化物

采用离子选择电极法对生活饮用水中氟化物浓度进行了测定。讨论了水样中pH值、温度、响应时间对测定结果的影响。在最佳条件下,方法的线性范围为0．10～3．0mg／L,相关系数为0．9999,检出限为0．05mg／L,实际水样加标回收率为97％～106％,相对标准偏差（n=5）为0．04％～0．65％。方法简单快速,干扰小,重现性好,加标回收率令人满意,能进行生活饮用水中氟化物浓度的有效测定。     

用氟离子电极对土壤中铝作直接电位法测定

本文提出用氟离子电极对土壤中铝作直接电位法测定。大大减少了以往的用终点电位滴定法测定土壤中铝含量的实验步骤与时间,并较大地提高了测定的准确度。方法是取一定量的土壤试液加入到pH为5,离子强度为1.0的缓冲溶液中,再加入一定量的F~-离子标液,让F~-与Al_(3 )络合稳定后,用氟离子电极测出溶液中的游离态F~-浓度,从而计算出Al~(3 )的总浓度。