表面活性剂增敏动力学光度法测定尿液中的微量SCN-

在pH 11.4的NH3-NH4Cl缓冲溶液中,阳离子表面活性剂溴代十四烷基吡啶(TPB)对硫氰酸根阻抑高碘酸钾氧化间甲酚紫的褪色反应具有明显的增敏作用,据此建立了动力学光度法测定微量SCN-的新方法,该方法的线性范围为0.04～0.72 μg/mL,检出限6.74×10-3 μg/mL.可用于测定吸烟和非吸烟者的尿液中的微量SCN-.     

新铜试剂-铜(Ⅰ)体系萃取原子吸收法间接测定微量硫氰酸根

本文研究了NCP-Cu(Ⅰ)·SCN-离子对的形成、萃取和测定条件;探讨了有机溶剂对测定灵敏度的影响。用于电镀厂排放水中微量硫氰酸根的测定,获得了满意的结果。     

毛细管离子色谱法同时测定饮用水中痕量碘离子、硫氰酸根和草甘膦

建立了一种采用毛细管离子色谱法同时测定饮用水中痕量碘离子(I-),硫氰酸跟(SCN-)和草甘膦(Glyphosate)的方法。样品经过0.22 mm滤膜过滤后,直接进样5 mL,采用IonPac AS19(250 mm×0.4 mm)毛细管色谱柱分离,KOH梯度淋洗,流速10 mL/min,抑制电导检测,外标法定量。以信噪比S/N=3计算检出限,I-,SCN-和草甘膦的检出限分别为0.3,0.2和0.2 mg/L,线性范围2.0~100 mg/L,相关系数分别为0.9997,0.9998和0.9998,加标回收率为86.0%~100.6%。本方法应用于饮用水中痕量I-,SCN-和草甘膦的测定,结果令人满意。     

直接电位法测定工业废水中的硫氰酸根离子

用直接电位法测定了统扑净生产废水和印染厂排放废水中硫氰酸根的浓度。在温度为 1 6℃ ,浓度为 0 .0 2 mol/L HCl的体系中 ,以功能高分子 PVC-双硫腙 -铜 ( I)载体的 SCN-离子电极在 SCN-离子浓度为 1 .0× 1 0 -2 ～ 5× 1 0 -6mol/L时呈能斯特响应 ,斜率为 58± 2 m V/dec,检出限为 2 .0× 1 0 -6mol/L。电极的选择性次序为 :SCN->>Cl O4 -～Sal->>Cl->NO3 ->HPO4 2 ->SO4 2     

丙醇-水体系萃取浮选铜间接测定硫氰酸根

试验表明, 在SCN-存在下, Cu(Ⅱ)能被抗坏血酸还原为Cu(Ⅰ), Cu(Ⅰ)与SCN-形成CuSCN沉淀, 该沉淀在丙醇与水分相过程中, 能很好的浮选于丙醇/水界面之间, 通过测定Cu(Ⅱ)浮选率, 能间接测定SCN-的量, 据此建立了测痕量SCN-的新方法, 多数常见阴、阳离子不干扰测定. 测定的线性范围为3.0×10-6～7.8×10-5 mol/L, 检出限为1.5×10-6 mol/L, 回收率为95.7%～103%. 用于尿样与唾液中SCN-的测定.     

离子色谱法测定水中的F-、Cl-、NO2--N、NO3--N、SO42-

应用DX－102型离子色谱仪测定水中的F^-、Cl^-、NO2^-－N、NO3^-－N及SO4^2-，淋洗液为1.42mmol/L NaHCO3-1.50mmol/L Na2CO3溶液，淋洗液流速为1.8mL/min，进样量为25μL。5种离子在上述实验条件下分离良好，定量测定的线性相关系数均在0.9995以上。     

新型中性载体PVC膜高选择性硫氰酸根电极研究

研究了新型Schiff碱对溴苯甲醛缩邻氨基酚过渡金属配合物的阴离子响应行为。实验结果表明:以Cu(Ⅱ)配合物为载体的电极对硫氰酸根具有优良的电位响应性能(pH4.0),电极的线性范围为1.0×10-1～2.0×10-5mol/L,斜率为-59.4mV/dec,检出限为9.0×10-6mol/L。其反Hofmeister选择性次序为:SCN->Sal->I->ClO4->NO2->NO3->Br->SO42->Cl-,研究了阴离子与载体的作用机理,结果表明SCN-与载体中铜原子直接作用。电极可应用于废水及人体唾液中SCN-的测定。     

根际土壤溶液中磷的毛细管电泳分析

应用毛细管区带电泳间接紫外吸收法,对测定根际土壤溶液中PO43-的检测波长、电泳温度、分离电压和电解液组成等参数进行了选择,发展了根际土壤溶液中PO34-浓度的毛细管电泳分析法。选择后的电泳条件为:电解液为32mmol/L三羟甲基氨基甲烷+4mmol/L1,2,4-苯三酸+0.3mmol/L十六烷基三甲基溴化铵(pH=8.5);检测波长为205nm,分离电压为-20kV,温度为25℃。本方法有效地屏蔽了土壤溶液中Cl-,SO42-和NO3-等离子对PO43-测定的影响,对根际土壤溶液中PO43-的检出限为0.68mg/L(S/N=3);回收率为87.2%～99.4%,适于测定微量根际土壤溶液样品中PO34-的浓度。     

3,5-二溴-PADAP 分光光度法测定微量离子的研究

系统研究了3,5-二溴-PADAP 在酸性介质中质子化后与 NO-2和 SCN- 形成三元离子缔合物的最佳条件.提出了测定微量 NO-2 的分光光度新方法,表观摩尔吸光系数 ε630=1.2×104L.mol-1.cm-1,缔合物组成比为 n(3,5-二溴-PADAP)∶n(NO2-)∶n(SCN-)=1∶1∶1.本法应用环境水体中微量的测定,与经典方法对照结果吻合.     

电聚合制备维生素B12修饰电极及其特性研究

以玻碳电极为工作电极,电聚合法制备VB12修饰电极,该修饰电极对亚硝酸根离子,亚硫酸根离子和肼均具有催化活性.在pH=2.3的磷酸缓冲底液中,电极对NO2-的催化氧化电位为0.76V(vs.SCE),催化氧化电流与NO2-的浓度在1.6×10-6～4.3×10-4mol.L-1范围内呈线性关系,其线性方程为ip=-24.68+12.36C,相关系数0.9987.应用该电极测定水中的NO2-,稳定性好,灵敏度高.     

Potentiometric Measurements in Non-Aqueous Media Using Bromide and Iodide Ion Selective Membrane Electrodes

Abstract

Solid membrane bromide and iodide ion selective membrane electrodes were evaluated for their performance in non-aqueous media. The electrodes were evaluated in several alcohols and glacial acetic acid.     

十二烷基二甲基苄基溴化铵离子选择电极的制备与性能

以四苯硼钠作为电活性物质,用溶胶-凝胶方法制备的阳离子表面活性剂离子选择电极对十二烷基二甲基苄基溴化铵具有良好的能斯特响应特性,其线性响应范围为1.0×10-3~1.58×10-6mol·L-1,斜率为57.8mV/pc(pc=-logc),适宜的pH范围为4.0~10.0.同时该电极显示了较好的选择性,重现性和稳定性.用该电极对十二烷基二甲基苄基溴化铵进行了回收率试验,效果很好,对其溶液试样进行了分析,结果和标准方法一致.     

Velocity map imaging of the photolysis of n-C4H9Br in UV region

Using velocity map ion imaging technique, the photodissociation of n-C₄H₉Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C₄H₉Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in C_s symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C₄H₉+Br (²P_3/2) or C₄H₉ + Br^* (²P_1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C₄H₉Br near 234 nm and 267 nm.     

Ion pairing of quaternary salts in solvent mixtures

Conductances at 25.00°C are reported for the following systems: tetrabutylammonium bromide in dimethyl sulfoxide-acetone mixtures (Bu₄NBr in Me₂SO–Me₂CO); tetraphenylphosphonium bromide (Ph₄PBr) in water Me₂SO, Me₂CO, and in the mixtures H₂O–Me₂SO, Me₂SO–Me₂CO and Me₂CO–H₂O; Ph₄PCl in Me₂SO, Me₂CO, H₂O–Me₂SO, and Me₂SO–Me₂CO; and tetrapropylammonium bromide (Pr₄NBr) in Me₂SO and Me₂CO. The data were analyzed using the Fuoss 1978 equation which is based on the coupled equilibria: (unpaired ions)(solvent-separated pairs)(contact pairs). The conductimetric pairing constantK _A =K _R(l+K _s) is the product of two factors:K _R, which describes the first (diffusion controlled) equilibrium andK _s=exp(–E _s/kT), which describes the second (system-specific) equilibrium. Ions with overlapping cospheres (of diameterR) are defined as paired: their center-to-center distancer lies in the rangearR; contact pairs (r=a) are ions which have one ion of opposite charge as a nearest neighbor, all other nearest and next nearest neighbors being solvent molecules. The quantityE _s is the difference in free energy between the states defined byr=R andr=a. For the Me₂SO–Me₂CO systems,E _s is positive for solutions in Me₂SO and decreases through zero to negative values as the fraction of the less polarizable acetone increases. For solutions in waterE _s is also positive. On addition of Me₂SO or Me₂CO,E _s initially increases, goes through a maximum, and then decreases to negative values as the fraction of the less polarizable component increases. The decrease is an electrostatic effect, common to all the systems. The initial increase inE _s appears when the small water molecules surrounding solvent-separated pairs are replaced by organic molecules which have greater volumes than water.     

Photodissociation study of ethyl bromide in the ultraviolet range by the ion-velocity imaging technique.

The photodissociation of ethyl bromide has been studied in the wavelength range of 231-267 nm by means of the ion velocity imaging technique coupled with a [2+1] resonance-enhanced multiphoton ionization (REMPI) scheme. The velocity distributions for the Br ((2)P(1/2)) (denoted Br*) and Br ((2)P(3/2)) (denoted Br) fragments are determined, and each can be well-fitted by a narrow single-peaked Gaussian curve, which suggests that the bromine fragments are generated as a result of direct dissociation via repulsive potential-energy surfaces (PES). The recoil anisotropy results show that beta(Br) and beta(Br*) decrease with the wavelength, and the angular distributions of Br* suggest a typical parallel transition. The product relative quantum yields at two different wavelengths are Phi(234nm)(Br*)=0.17 and Phi(267nm)(Br*)=0.31. The relative fractions of each potential surface for the bromine fragments' production at 234 and 267 nm reveal the existence of a curve crossing between the (3)Q(0) and (1)Q(1) potential surfaces, and the probability of curve crossing decreases with the laser wavelength. The symmetry reduction of C(2)H(5)Br from C(3v) to C(s) invokes a nonadiabatic coupling between the (3)Q(0) and (1)Q(1) states, and with higher energy photons, the probability that crossing will take place increases.     

四溴汞(Ⅱ)酸钾-异辛基苯二聚乙二醇醚二甲基苄基氯化铵的共振散射光谱及其分析应用

在pH2～8的溶液中,四溴汞（Ⅱ）酸钾和异辛基苯二聚乙二醇醚二甲基苄基氯化铵（BTC）反应生成离子缔合物,在390nm处有一共振散射峰,峰强度随汞（Ⅱ）质量浓度的增加而增大,据此建立了测定痕量汞的新方法。在实验条件下,此法测定汞（Ⅱ）的线性范围是14～240μg/L,检出限为μg/L,已用于合成水样和环境水样中汞（Ⅱ）的测定。     

Ion-Chromatographic Determination of Low Concentrations of Nitrate in Solutions of High Salinity

The determination of low concentrations of inorganic anions in water samples of high salinity is one of the most difficult tasks in analytical chemistry. There is, however, an increasing demand for the exact and reliable determination of nutrients even at very low concentration levels in environmental samples of complex composition. We therefore present the development, quality control and application of an easy and rugged method that makes possible the determination of trace amounts of nitrate in solutions with high concentrations of chloride (>30 000 mg L⁻¹) and a hundred-fold excess of bromide ions, based on ion chromatography with UV detection at λ = 210 nm. While chloride ions show no absorbance at this wavelength, a bromide concentration >1500 μg L⁻¹ severely interferes with nitrate determination at the trace level. On the contrary, at nitrate concentrations of >500 μg L⁻¹, this bromide interference becomes negligible. Consequently, to overcome the impact of bromide on the trace level determination of nitrate, all samples are spiked with a definite volume of a nitrate standard solution to obtain an overall nitrate concentration of >500 μg L⁻¹ which allows the exact and reliable determination of nitrate concentrations down to 25 μg L⁻¹. We will report the successful application of the method to samples of high salinity.     

溴离子选择电极法测定有机化工产品中四丁基溴化铵的残留

建立了有机化工产品中四丁基溴化铵残留测定的新方法。该法线性范围为0.01~0.10 g/L,检出限为0.4 mg/L,相对标准偏差为2.4%(0.05 g/L,n=11),相关系数为0.998,用于实际样品测定,结果令人满意。     

The effect of alkyltrimethylammonium bromides on the thermal stability of dioctadecyldimethylammonium bromide (DOAB) vesicles in aqueous solutions

The influence of alkyl chain length in alkyltrimethylammonium bromides on the gel to liquid crystal transitions in DOAB versicles is examined using differential scanning microcalorimetric data. The changes in melting temperature, patch number and standard enthalpy of melting for DOAB vesicles depend strongly on added surfactants and their concentration. The data show that vesicles are readily penetrated by surfactant molecules when the vesicles are in the liquid crystal state and the penetration is facile when the length of alkyl chains in both surfactants and vesicles are comparable. Furthermore, the vesicles are made up of domains that differ in composition.     

On the adsorption and condensed film formation of binary mixtures of dodecyl-, tetradecyl-, hexadecyl-, and octadecyl-trimethylammonium bromides at the mercury–electrolyte interface

The adsorption and condensed film formation on mercury at the negative potential region for binary mixtures of dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB) is studied in KBr at various temperatures from 5 to 45 °C. The formation of the CTAB condensed film is hindered with the addition of DTAB and TTAB. There are interactions between unlike hydrophobic chains. The strong interactions between the CTAB molecules do not take place when DTAB or TTAB is present above a certain concentration. This hindering is more pronounced in the case of TTAB compared to the same DTAB concentration, i.e. the increase of the chain length hinders the film formation. The initially adsorbed molecules play a templating role in the kinetics of the film formation and in the self-assembling of the molecules. The initial induction time strongly depends on the temperature. The less surface active CTAB can hinder the OTAB film formation in binary mixtures. Also, increased interaction between OTAB and CTAB can be observed, indicating synergy effects in the film formation in some cases. The temperature range that the film is formed can be changed using mixtures of surfactants. Thus, the development of the film can become impossible, more difficult or even easier. Hysteresis phenomena are observed. The capacity versus time curves in the case that condensed film is formed are treated with the Avrami plot formulation, giving values between 1.5 and 2 indicating a progressive one dimensional nucleation with constant growth rate or a decrease of the nucleation rate during the overall film formation. There is generally a marked effect of the chain length of the alkyl chain on the film formation.