生活饮用水中氟离子含量的测定

为获取昭通市昭阳区生活饮用水中氟离子含量的科学数据和检测氟离子含量是否在国家规定标准要求内,通过氟离子选择电极法对昭通市昭阳区八个地方的生活饮用水中氟离子含量进行了测定,测得各水样的p H值在6. 66～7. 63之间,氟离子含量在0. 0551～0. 1512 mg/L之间,且氟含量都符合国家标准值(0. 05～1. 0 mg/L)。所测定的氟离子加标回收率范围在93%～97%,RSD在0. 15%～1. 18%之间,说明本实验所采取的方法便捷有效,氟离子选择电极法测定准确,可靠。     

离子选择电极法测定磷石膏中全氟含量

磷石膏中的氟限制了磷石膏在水泥和建材等领域的应用,因此了解磷石膏中的氟含量非常重要.对磷石膏中的氟含量的测定方法进行了探讨.通过实验提出了用碳酸钠熔融磷石膏样品,用柠檬酸钠-冰醋酸作为总离子强度调节缓冲溶液,采用离子选择电极法测定磷石膏中的全氟含量.该方法氟离子质量浓度检出限为0.34 mg/L,氟离子回收率为88.5%～90.3%,氟离子质量浓度线性范围为0～5 mg/L,线性相关系数R2=0.999 1,相对标准偏差为1.2%(n=7).该方法是一种简便、快捷、灵敏度较高的测定磷石膏中全氟含量的方法.     

离子色谱测定氟树脂涂料中溶剂可溶物氟含量的检测方法研究

详细介绍了离子色谱仪测定氟树脂涂料中溶剂可溶物氟含量的检测方法,通过方法验证试验表明,本方法线性范围广,检出限和定量限低,精密度良好,回收率高。     

分光光度法测定牙膏中游离氟的含量

在碱性条件下,氟离子能使Fe3+与硫氰酸根反应生成的血红色配合物的吸光度下降,氟离子的加入量与体系吸光度的改变值成正比,且氟离子质量浓度在2.0～100.0 mg.L-1内与吸光度呈良好线性关系,线性回归方程为A495=0.002 98ρ+0.039 5,线性相关系数为0.998 3。据此建立了一种利用Fe3+与硫氰酸钾体系光度法测定氟离子的方法,并将该法用于牙膏中微量氟离子含量的测定,测定结果与氟离子选择电极法测定结果一致。     

化工标准化动态

相关膜系列标准 1）HJ 480—2009《环境空气氟化物的测定滤膜采样氟离子选择电极法》。规定了测定空气中氟化物含量的滤膜采样氟离子选择电极法。适用于环境空气中氟化物的小时含量和日平均含量的测定。2）HY/T 065—2002《聚偏氟乙烯微孔滤膜》。规定了聚偏氟乙烯微孔滤膜型号编制、技术要求、试验方法、检验规则、包装与运输和储存,适用于气体净化用的偏氟乙烯微孔膜。     

耐污损涂料

9802214防污剂、涂料组合物及其户外物件:Jp97一03435〔日本专利公开〕/日本:Daikin IndLtd(Mori、Haruhiko等)一1997.1.7一14页一95/156359(1995.6,22);JPC C09K3/()044耐污损涂料、汽车涂料1998年 该涂料组合物含有带(A)乙烯基、径基、氨基或环氧基,(B)含F烷基和(C)梭酸或磺酸离子基的化合物(用作防污剂)和带经基和/或淡基的可溶于溶剂的氟烯烃共聚物。该涂料组合物由(A)可溶于溶剂的含经基和/或梭基和Rf-CqeR‘x,eRZxZCOZ(Rf二含F烷基:x‘、xZ=SO3M、H、Cl一20烷基、环烷基、芳基或芳烷基,至少有一个为SO3M,M=Li、Na、K…     

磷矿中氟含量的测定

国家标准GB 1872-80对磷矿中氟含量测定分析方法有:硝酸钍容量法与氟离子选择电极法两种。笔者经过多年的工作经验认为,选用氟离子电极法操作简便、快速,仅50 min即可完成测定,准确度、精密度较好,符合中控的要求。1氟离子选择电极法实验1.1实验原理称取经研磨与烘干的试样0.1～0.2g(±0.0001 g),用盐酸分解,用柠檬酸三钠和盐酸溶液调节溶液pH=5.5～6.0。使用电位测量仪以饱和甘汞电极为参比电极,氟离子选择电极为指示电极,测得试液的电位值后,再加入标准氟溶液测得电位值,得到两个电位值的差,经计算可求出试样氟的含量。1.2仪器和试剂1)…     

基于氟铝配位的鳌合树脂吸附氟的可行性分析

针对传统树脂吸附除氟选择性不强的问题,提出了一种先向废水中投加铝离子进行氟铝配位,再利用螯合树脂吸附氟铝配合物的新方法。为了考察水溶液中的氟离子转型为氟铝配合物的可行性,对H~+-F~--Al~(3+)-H_2O体系中F/Al摩尔比和平衡pH的影响进行了热力学分析。结果表明:F/Al摩尔比=1、平衡pH=1～8时,水中游离氟离子全部转型为氟铝配合物,有助于螯合树脂对氟的选择性吸附。     

水性氟碳涂料中氟含量测试方法及其影响因素的分析

主要介绍了化工行业标准HG厂T4104—2009《建筑用水性氟涂料》这几年来的实施情况，检测氟含量的意义，以及离子选择电极法的优缺点，讨论了水性氟碳涂料测试氟含量的过程中的一些影响因素，重点介绍了离心过程、仪器、燃烧过程的对氟含量测试的影响。     

磷酸氢钙中微量、痕量氟的测定

本文提供了用蒸馏-仪器比色法和氟离子选择电极法测定食品级磷酸氢钙中微量、痕量氟的方法。与现行测定方法GB1889-80相比,这两种方法数据更为准确,而且氟离子选择电极法无需对试样进行蒸馏处理。蒸馏-仪器比色法F′回收率为102-110%;氟离子选择电极法F′回收率为92.5-111%。     

氟树脂涂料中氟含量测定方法的探讨

讨论了以氧气瓶燃烧法分解氟树脂,把氟树脂中的氟转化为氟离子,然后以硝酸镧标准溶液进行滴定,从而测定出氟树脂中的氟含量,再根据定量关系计算出氟树脂涂料中的氟含量的方法。该方法简单易行,准确可靠,省时省力。     

氟碳漆中氟碳树脂含量的分析方法研究

采用氧弹燃烧法配合氟离子电极对有机溶剂型和水溶性氟碳漆中氟碳树脂含量的分析方法进行了研究.结果表明,采用氧弹燃烧法配合氟离子电极对有机溶剂型氟碳漆及处理后水溶性氟碳漆的氟碳树脂含量能够进行准确测定.     

氟含量与氟碳涂料性能关系浅析

综述了含氟聚合物的应用原理、测试方法及氟含量,分析了氟含量对氟涂料耐久性的影响。     

白炭黑中氟含量的测定方法

介绍了利用磷肥企业含氟硅渣生产白炭黑工艺中,白炭黑中氟含量的分析方法。对氧硅酸钾法、电极法、比色法3种氟含量分析方法进行了比较,得出电极法操作简单,能快捷地分析出氟含量,是较合适的分析方法;如氟含量较高,采用氟硅酸法分析比较合适。     

C-F and C-H bond activation of fluorobenzenes and fluoropyridines at transition metal centers: how fluorine tips the scales

In this Account, we describe the transition metal-mediated cleavage of C-F and C-H bonds in fluoroaromatic and fluoroheteroaromatic molecules. The simplest reactions of perfluoroarenes result in C-F oxida tive addition, but C-H activation competes with C-F activation for partially fluorinated molecules. We first consider the reactivity of the fluoroaromatics toward nickel and platinum complexes, but extend to rhenium and rhodium where they give special insight. Sections on spectroscopy and molecular structure are followed by discussions of energetics and mechanism that incorporate experimental and computational results. We highlight special characteristics of the metal-fluorine bond and the influence of the fluorine substituents on energetics and mechanism. Fluoroaromatics reacting at an ML(2) center initially yield η(2)-arene complexes, followed usually by oxidative addition to generate MF(Ar(F))(L)(2) or MH(Ar(F))(L)(2) (M is Ni, Pd, or Pt; L is trialkylphosphine). The outcome of competition between C-F and C-H bond activation is strongly metal dependent and regioselective. When C-H bonds of fluoroaromatics are activated, there is a preference for the remaining C-F bonds to lie ortho to the metal. An unusual feature of metal-fluorine bonds is their response to replacement of nickel by platinum. The Pt-F bonds are weaker than their nickel counterparts; the opposite is true for M-H bonds. Metal-fluorine bonds are sufficiently polar to form M-F···H-X hydrogen bonds and M-F···I-C(6)F(5) halogen bonds. In the competition between C-F and C-H activation, the thermodynamic product is always the metal fluoride, but marked differences emerge between metals in the energetics of C-H activation. In metal-fluoroaryl bonds, ortho-fluorine substituents generally control regioselectivity and make C-H activation more energetically favorable. The role of fluorine substituents in directing C-H activation is traced to their effect on bond energies. Correlations between M-C and H-C bond energies demonstrate that M-C bond energies increase far more on ortho-fluorine substitution than do H-C bonds. Conventional oxidative addition reactions involve a three-center triangular transition state between the carbon, metal, and X, where X is hydrogen or fluorine, but M(d)-F(2p) repulsion raises the activation energies when X is fluorine. Platinum complexes exhibit an alternative set of reactions involving rearrangement of the phosphine and the fluoroaromatics to a metal(alkyl)(fluorophosphine), M(R)(Ar(F))(PR(3))(PR(2)F). In these phosphine-assisted C-F activation reactions, the phosphine is no spectator but rather is intimately involved as a fluorine acceptor. Addition of the C-F bond across the M-PR(3) bond leads to a metallophosphorane four-center transition state; subsequent transfer of the R group to the metal generates the fluorophosphine product. We find evidence that a phosphine-assisted pathway may even be significant in some apparently simple oxidative addition reactions. While transition metal catalysis has revolutionized hydrocarbon chemistry, its impact on fluorocarbon chemistry has been more limited. Recent developments have changed the outlook as catalytic reactions involving C-F or C-H bond activation of fluorocarbons have emerged. The principles established here have several implications for catalysis, including the regioselectivity of C-H activation and the unfavorable energetics of C-F reductive elimination. Palladium-catalyzed C-H arylation is analyzed to illustrate how ortho-fluorine substituents influence thermodynamics, kinetics, and regioselectivity.     

水性氟涂料氟含量的测试方法

介绍了水性氟涂料的乳液和颜填料分离方法，以及氟含量试验结果。给出了合适的测试方法。     

Fluorine interactions at the thrombin active site: protein backbone fragments H-C(alpha)-C=O comprise a favorable C-F environment and interactions of C-F with electrophiles

In a systematic fluorine scan of a rigid inhibitor to map the fluorophilicity/fluorophobicity of the active site in thrombin, one or more F substituents were introduced into the benzyl ring reaching into the D pocket. The 4-fluorobenzyl inhibitor showed a five to tenfold higher affinity than ligands with other fluorination patterns. X-ray crystal-structure analysis of the protein-ligand complex revealed favorable C-F...H-C(alpha)-C=O and C-F...C=O interactions of the 4-F substituent of the inhibitor with the backbone H-C(alpha)-C=O unit of Asn98. The importance of these interactions was further corroborated by the analysis of small-molecule X-ray crystal-structure searches in the Protein Data Base (PDB) and the Cambridge Structural Database (CSD). In the C--F...C=O interactions that are observed for both aromatic and aliphatic C-F units and a variety of carbonyl and carboxyl derivatives, the F atom approaches the C=O C atom preferentially along the pseudotrigonal axis of the carbonyl system. Similar orientational preferences are also seen in the dipolar interactions C--F.C[triple chemical bond]N, C-F.C-F, and C-F...NO(2), in which the F atoms interact at sub-van der Waals distances with the electrophilic centers.     

磷肥副产硅胶中氟含量的测定

采用离子选择性电极法测定磷肥副产硅胶中的氟含量。提出用盐酸浸出磷肥副产硅胶中的氟杂质,以柠檬酸-柠檬酸三钠缓冲溶液作总离子强度调节剂。该方法的检出限为0.05mg/L(以F-计),相对标准偏差为2.34%(n=18),加标回收率为96.50%～99.25%。     

The quantitative analysis of fluorocarbon polymer finishes on wool by FT-IR spectroscopy

Two contrasting infrared spectroscopic techniques, Attenuated Total Reflectance (ATR) and PhotoAcoustic Spectroscopy (PAS), have been investigated as means for the determination of fluorocarbon polymer finishes on wool fabric. Based on the experimental conditions used, the results of the PAS method are more characteristic of the bulk sample, while the ATR results are more surface specific. Linear calibrations between polymer addon, as determined by total fluorine analysis, and the absorbance of the C? F stretching bands of the normalized spectral data were obtained for a typical commercial fluorocarbon polymer. The correlation obtained for the PAS method was found to be significantly better than that of the ATR method. The lower limit of detection of fluorocarbon polymers on wool using the PAS technique was 0.25% on the weight of the wool (oww). In contrast, fluorocarbon polymer add-ons as low as 0.125% oww (approximating monolayer coverage) could be analyzed using the ATR method. At high levels of add-on, the ATR calibration deviated from linearity. This can be attributed to the distribution of fluorocarbon polymer on the surface of the fiber, in particular, the build up of polymer on the cuticle cell edge regions. The quantitative methods developed are used to help access the effects of wear and the subsequent heating of fluorocarbon polymer-treated fabric samples. © 1995 John Wiley & Sons, Inc.     

不同氟含量氟碳树脂的折射率及实用性研究

采用氟烯烃与丙烯酸酯共聚的方法合成了氟含量(质量分数)分别为20%,35%的氟碳树脂,采用含氟丙烯酸酯直接共聚的方法合成了氟含量为50%的氟碳树脂。采用傅里叶变换红外光谱分析氟含量为20%和35%的氟碳树脂结构,结果表明合成的这两种氟碳树脂中含有氟基团;采用椭偏仪测试了树脂的折射率,结果表明3种氟碳树脂的折射率均低于丙烯酸树脂,氟含量为20%和35%的氟碳树脂的折射率相差不大,而氟含量为50%的氟碳树脂的折射率相对较高;采用X射线光电子能谱仪分析了3种氟碳树脂涂覆膜正反面的氟元素分布情况,结果表明随着氟含量的增加,膜正面氟含量逐渐增加至饱和,继续增加氟含量只会增加膜反面的氟含量;最后分别测试了树脂的抗污性能和附着力,结果表明氟含量为20%及35%的氟碳树脂在具有较低折射率的同时兼具良好的附着力及抗污性能。