氧弹燃烧–自动电位滴定法测定助焊剂中的卤素

建立氧弹燃烧–自动电位滴定法测定助焊剂中卤素的分析方法。在氧弹罐加入20 mL 0.25 mol/L氢氧化钠溶液作为吸收液,通过氧弹罐燃烧使得助焊剂中共价态的卤素转变成为离子态,利用氢氧化钠溶液吸收氧弹燃烧所释放的离子态卤素,吸收后的溶液用硝酸溶液(1∶1)进行酸化,消除碳酸根、碳酸氢根、氢氧根离子的干扰。处理后的样品溶液用0.01 mol/L硝酸银标准溶液进行滴定。助焊剂样品中卤素测定结果的相对标准偏差为0.51%～3.24%(n=5),加标回收率为95.24%～100.49%。该方法样品处理简单,操作简便,成本低廉。     

多元校正双指示电极电位沉淀滴定法同时测定混合卤素离子

建立一种可同时测定混合卤素离子的电位滴定新方法.在这种方法中,滴定剂是硝酸银和氟化钠的混合溶液,被滴定液中同时插入了氟离子指示电极和银离子指示电极.在滴定过程中的任一滴定点,溶液中Ag 的浓度和滴定剂的加入体积可由两个电极的电位测定值同时获得,从而可应用多元校正法由相应的滴定曲线求得混合卤素离子中每一种离子的含量.用该方法对混合物样品中的Cl-、Br-、I-进行了同时测定,测定结果的相对标准偏差为0.13%～0.45%(n=5),回收率为97.3%～103.4%.     

自动电位滴定法测定乙烯利含量

乙烯利 ( 2 -氯乙基膦酸 )是植物生长调节剂。其测定方法有纸层析定磷法、定乙烯法和水解测氯法。通常采用的是水解测氯法 :在碱性和加热回流条件下 ,乙烯利离解出氯 ,然后以铁铵矾为指示剂 ,加入过量硝酸银标准溶液 ,再用硫氰酸铵标准溶液回滴。本文在乙烯利水解后 ,采用自动电位滴定法直接滴定氯 ,操作简便、快捷 ,结果的精度较高。1　试验部分1 .1　主要仪器与试剂751 GPD Titrino自动电位滴定仪 ,1 0 ml交换单元 ,银复合电极 (瑞士 Metrohm公司 )氢氧化钠溶液 :0 .1 mol· L- 1硝酸银标准溶液 :0 .0 5mol·L- 1酚酞指示剂 :5g· L- …     

离子选择性电极电位滴定法测定维生素B1的含量

1 引言 维生素B1化学名称为氯化4-甲基-3-[(2-甲基-4-氨基-5-嘧啶基)甲基]-5-(2-羟基乙基)噻唑盐酸盐,作为一种药物,可以维持正常糖代谢及神经消化系统功能,用于防治缺乏维生素B1所致的脚气病,也用于神经炎、消化不良等症的辅助治疗.目前我国药典法规定维生素B1注射液及其片剂中维生素B1含量采用分光光度法测定.国外有人研究采用银离子选择性电极,在0.5mol/L NaOH溶液中用电位滴定法测定维生素B1含量,而国内未见报道.本研究采用离子选择性电极,在水溶液中用电位滴定法测定维生素B1的含量.     

电位滴定法测定氰尿酸的含量

氰尿酸（CA），学名2，4，6-三羟基-1，3，5-三嗪。CA在工业上的生产均以尿素为原料，它是一个非常重要的化工产品的中间体，被广泛地应用于合成各种油漆、涂料、除草剂、杀菌剂、漂白剂、金属氰化缓蚀剂以及高分子材料的粘合剂、改性剂、交联剂、抗氧剂等。在有关氰尿酸的生产及科研中，经常要对其含量进行分析，在目前常用的分析方法中，薄层色谱分析方法可靠，但有时受仪器设备等条件的限制；重量分析法（氰尿酰胺沉淀法）和非水酸碱滴定法，操作繁琐且花费时间较长或条件苛刻；以酚酞或甲基红作指示剂进行水相酸碱滴定，结果误差比较大。本文用电位滴定法在水相对氰尿酸的含量进行酸碱滴定分析。     

电位滴定法连续测定线路板裂解残渣中微量氯和溴

印刷电路板样品经热降解和去卤化处理后,所得试样残渣中残留的氯和溴离子用电位滴定法连续测定.采用硝酸银标准溶液作为滴定剂,滴定系在有一定量的硝酸钾存在的稀硝酸溶液中进行,滴定终点取滴定曲线上两离子突跃部分斜率的最大值处或其一次微分曲线上相应的最小值处.计算测定结果采用了标准曲线法及标准加入法,并对此两方法的精密度和准确度作了比较.结果表明:标准加入法具有更高的精密度,测定其相对标准偏差(n=6)为2.85%(溴离子)和1.86%(氯离子),经F检验法证明,特别对微量溴及氯的测定采用标准加入法更为有利.     

自动电位滴定法测定磺酸盐合成及产品中硫酸钠

石油系磺酸盐合成及产品 (如凝土外加剂 )中硫酸盐的测定 ,对控制磺酸盐质量具有重要意义。目前 ,磺酸盐产品中硫酸盐测定多采用“混凝土外加剂匀质性试验方法”中硫酸钡重量法或离子交换重量法[1 ] ,此法手续繁琐 ,尤其是费时 ,周期约 48ｈ ,难以满足生产特别是工艺开发阶段条件试验时调整工艺参数的要求。用铅离子作滴定剂 ,铅离子选择性电极为指示电极 ,电位滴定法测定硫酸盐是一种比较可靠的方法 ;用于磺酸盐中硫酸盐的分析 ,目前尚未见报道。作者运用计算机控制的自动电位滴定法[2 ] ,选择了适合在磺酸盐中进行测定的滴定介质、酸度、…     

自动电位滴定法快速测定钾盐中的钾含量

钾含量的测量常用火焰光度法和四苯硼钾重量法。火焰光度法适用于微量分析 ,对较高含量钾的测定误差较大 ,四苯硼钾重量法的测定准确度高 ,但操作繁琐 ,测定周期长 ,易出错。本文采用四苯硼钠溶液电位滴定法 ,测定高、中含量组分钾 ,测定周期短 ,所用试剂少 ,且不受样品中水不溶物的干扰 ,选择性好 ,测定的准确度和精密度均在 0 .2 %以下 ,适用于钾盐、卤水、复合肥和钾肥中钾的测定。1　实验部分1 .1　仪器和药品ZD 2型自动电位滴定仪 (上海雷磁仪器厂 ) ,PK 1型钾离子选择电极 ,2 1 7型饱和甘汞电极 (双盐桥 )。四苯硼钠标准液 :0 .1mol…     

混合离子的沉淀准确滴定

用沉淀滴定的林邦滴定曲线方程推导滴定突跃的绝对值,用滴定突跃的绝对值推导混合离子准确滴定的条件。     

Activity Coefficients of Individual Ions from Titration Data

It is shown that the activity coefficients of the anions resulting from the dissociation of a weak polyprotic acid can be obtained from titration data. Activity coefficients are determined in terms of the activity coefficient of the undissociated acid. The extracted activity coefficients are also dependent on the pH scale adopted in the titration process and are considered as operational coefficients. The computational procedure uses an exact equation representing the titration curve and a nonlinear least-squares fitting procedure. As an illustration, the activity coefficients of the anions of succinic acid are determined. The method also allows study of the variation of the activity coefficients with the ionic strength in a straightforward manner.     

Three Isomeric Chiral Metal-organic Frameworks Determined by Different Halogen Ions

Three isomeric metal-organic frameworks,[Cd2（X）（btc）（DMA）3]n（X = Cl（1）,Br（2）,I（3）,H3btc =1,3,5-benzenetricarboxylic acid and DMA = N,Nˊ-dimethylacetamide）,have been synthesized and characterized by elemental analysis,infrared spectra（IR）,thermogravimetric（TG） analyses and single-crystal X-ray diffraction.Single-crystal X-ray analysis reveals that compounds 1–3 crystallize in the orthorhombic P212121 space group,and feature a three-dimensional（3D） extended framework containing dinuclear [Cd2（COO）3] units as the secondary building units（SBUs）.Topological analysis reveals that compounds 1–3 can be simplified into a 3-connected srs topological network.     

Potentiometric Titration of Some Sulphide Forming Ions by Dithiopyrilmethane

Dithiopyrilmethane (DTPM) is the sulphur containing derivative of pyrazolone. This reagent forms active mono- or biprotonated form giving stable, often colored complexes with sulphide forming metal ions. It is the most common that the reagent as a bidentate neutral ligand exists in these complexes giving cation or neutral complexes. This reagent is used in spectrophotometric and extractive spectrophotometric methods of analysis of sulphide forming metal ions.     

EDTA滴定法连续测定铅精矿中铅和锌

建立了EDTA滴定法连续测定铅精矿中铅和锌的方法。试样用盐酸、硝酸、硫酸和氯酸钾分解。铅通过硫酸铅沉淀与其他干扰元素分离,沉淀溶解于乙酸-乙酸钠溶液中。在滤液中加入氨水、氟化钾使铁等干扰元素沉淀并与锌溶液分离。用二甲酚橙作指示剂,EDTA分别滴定溶液中的铅和锌。研究中测定了能力验证NILPT(2010)-0211铅精矿样品10-1和10-2中铅和锌,结果满意。     

固相萃取―离子色谱法测定工业废水中卤素

采用LC-C18柱-IC-Na柱串联,对样品进行固相萃取,以离子色谱法对工业废水中的卤素进行快速测定。选定的色谱条件是Ion Pac AS22离子交换柱、4.5 mmol/L(Na_2CO_3)+1.4 mmol/L(NaHCO_3)混合液作淋洗液,流速为1.2 m L/min,抑制型电导检测。氟、氯、溴、碘四种卤素在0~10.0 mg/L的浓度范围内线性关系良好,相关系数均大于0.999 0,检测限(3倍噪声比)分别为0.015、0.017、0.025和0.034 mg/L,相对标准偏差分别为0.98%、0.76%、0.82%和0.69%,回收率为95.02%~97.85%。该方法具有简便、准确、灵敏等特点,可较方便地应用于工业废水的质量检测和控制。     

混合离子配位滴定的离子强度允许范围

The applicable range of ionic strength of mixed ions coordination titration can be deduced by using the side-reaction coefficient of ionic strength, conditional stability constant and criteria for the accurate coordination titration for mixed icons.     

Hydration of Bromine Ions in Water

A mass spectrographic method electrospraying electrolyte solutions in vacuum was used to determine the enthalpy of hydration of bromine ions by different numbers of water molecules. The mass spectra of negative ions from aqueous solutions of NaBr were measured over the temperature range of 15–50°C and showed that the most intense peaks correspond to the hydrated bromine ions with one and two water molecules. It was found that the Van't Hoff equation holds for bromine hydrates containing up to three water molecules, whereas addition of the fourth water molecule leads to a violation of the Van't Hoff equation. The enthalpy of bromine ion hydration by the first and the second water molecules was found to be –(28.5 ± 1.7) and –(21 ± 4.2) kJ/mol, respectively.     

Halogen Bonding Adsorbent Pyridine N-oxides for Iodine Capture in Water

Rapid capture of ¹²⁹I with high volatility and toxicity in the environment has attracted much attention. Herein we reported a firstly synthesized nonporous material: pyridine N-oxides (NTPO and ATPO) as iodine adsorbent. Both of NTPO and ATPO exhibit remarkable performance on the adsorption of iodine in aqueous solution, vapor state and organic solvents. Upon the capture of iodine, pyridine N-oxides were transformed to binary cocrystals combined with the pyridine N-oxides and iodine which is driven by halogen bond between iodine and oxygen atoms. Moreover, pyridine N-oxides shows high chemical, thermal and moisture stability.     

An Interfacial Voltaic Cell for End Point Detection in Complexometric Titration of Metal Ions

An interfacial voltaic cell was firstly described by B. Waligra et al for the potentiometric titration of alkaloids in non-conducting solution.Our group had developed an improved one for the potentiometric titration of various alkaloids and their salts as well as pharmaceutical preparations,organic acids inorganic acids and bases. It had also been used as an end-point indicator for the potentiometric redox titration, and precipimetric titration.