Determination of pKa values of alendronate sodium in aqueous solution by piecewise linear regression based on acid-base potentiometric titration

As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and p H value based on acidbase potentiometric titration reaction.The distribution curves of alendronate sodium were drawn according to the determined p Ka values.There were 4 dissociation constants(pKa_1=2.43,pKa_2=7.55,pKa_3=10.80,pKa_4=11.99,respectively) of alendronate sodium,and 12 existing forms,of which 4 could be ignored,existing in different p H environments.

Pitfalls and Uncertainties of Using Potentiometric Titration for Estimation of Plant Roots Surface Charge and Acid-Base Properties

Amount and properties of roots surface charge are important for nutrient uptake and balance in plants. Roots surface charge markedly varies at different rizosphere conditions (particularly pH and ionic strength), which can markedly alter during vegetation season. Among recently available measuring methods, surface charge-pH dependence of roots (as well as other biological objects) is most easily evaluated by potentiometric titration. Use of this method is also easy at different ionic strengths. Potentiometric titration also allows for estimation of the distribution of charge generating surface groups. However, many applications of this method seem to be based either on incorrect methodical or theoretical approaches. In this paper we discuss the methodical and theoretical backgrounds of the titration method. Basing on experimental titration curves of roots of barley grown in nutrient solution, we show inconsistency of surface charge results obtained at different measuring conditions. Limitations of theoretical interpretations of the results are outlined also.

Investigation of a Simple and Cheap Source of a Natural Indicator for Acid-Base Titration: Effects of System Conditions on Natural Indicators

This study investigated a natural indicator for acid-base titration which is extracted from guinea corn leaves popularly called “waakye leaves” in Ghana. Four types of acid-base titration were studied: strong acid versus (v/s) strong base, strong acid versus weak base, weak acid versus strong base, and weak acid versus weak base. The indicator color change, pH range and the average titre values were determined for each type of acid-base titration. These values were comparable to those obtained from three standard indicators: methyl orange, methyl red and phenolphthalein. Total flavonoids (TF) and condensed tannin (CT) from the crude leaves extract were determined which might be the major reasons for the activity of the extract as an indicator for simple acid-base titration. The authors suggest that the natural indicator is cheap, available, simple to extract, user and environmentally friendly and could be an excellent replacement for standard indicators.

Triphenylmethanol and Tris(2-(hydroxymethyl)phenol) Derivatives: Synthesis and Application as Indicators for Acid-Base Volumetric Titration

Polyphenols are naturally occurring compounds found largely in fruits, vegetables, cereals and beverages. Currently, there is much interest in the potential health benefits of dietary plant polyphenols as antioxidants. The effect of polyphenols on human cancer cells is most often protective and induces a reduction in the number of tumors or rate of growth. During our course of study on anticancer prodrugs, twelve triphenylmethanol and one tris(2-(hydroxymethyl) phenol derivatives were synthesized as a carrier of several drugs with optimized lipophilicity. Besides application of these compounds as a foundation for anticancer drug delivery systems, these compounds were evaluated as indicators for the acid-base volumetric titration of a standard solution of hydrochloric acid with a standard solution of sodium hydroxide. The experiments indicated a moderate-to-sharp color transition of the solutions near the neutralization point for most indicators. These indicators may have potential applications for acid-base titrations in a narrow range.

Numerical Method for Determination of Composition of Weak Acid Mixtures by Potentiometric Titration

An equation describing the state of weak acid mixtures was derived from the relationships between mole balance and charge balance. The equation was solved with numerical method and the compositions of the acid mixtures were determined. The advantages of this treatment were demonstrated by analyzing binary mixtures of chloroacetic, formic and acetic acids.

QUANTITATIVE ANALYSIS OF VERY WEAK ACID AND BASE BY pH-FIXED TITRATION METHOD

pH-fixed titration method for the determination of weak acids and bases has been studied in this paper.It is not necessary to know the ionization constant of weak acid or base and the concentration of titrant. This method had been applied to determine phenol,4-aminoantipyrine and glycine,whose ionization constants range from 10^(-10)to 10^(-12).The results were satisfactory.

Titration Method Validation of Live Vaccines against Infectious Bursal Disease

Validating a method of analysis goes through different steps, which aims at testing the normality of measurements distribution, estimating the uncertainty of the components of a measurement （i.e., accuracy and correctness）, and finally, define the control tests of non degradation of the method performances. This paper outlines the steps for validating a biological method of analysis. It involves the construction of an experimental design, a statistical model, and the preparation of an interne laboratory reference material （pilot vaccine）. The latter is used to study the impact of deviation and variation factors, in order to, optimize the analytical method, to evaluate the bias （random error）, and to calculate the uncertainty of measurement, and make the control charts. This method is applied in the titration of live viral vaccines of Gumboro disease on chicken＇s embryos fibroblasts. The experimental results show that potential influence factors related to the titration method had no significant influence on the obtained results. Taking into account these results, an operating mode has been elaborated. The finalized method proved to be faithful to standard deviation of repeatability and reproducibility of 0.21 and 0.22, respectively, with a confidence level of 95%. The calculated uncertainty of measurement is equal to 0.2, which represents the average error level of a titer. A homogeneous stock of interne laboratory reference vaccine （MRIL）, with an average titer of 5.9 log DIT 50, was produced and the control chart set in away to provide the laboratory with an important tool of control and monitoring of the viral titers evolution in time, as well as, the mastery of the validated titration method performances.

Acid-base characterization of foursulfide minerals

The amphoteric properties of four sulfide minerals were characterized byacidimetric-alkalimetric titration. Chalcocite, galena, and sphalerite were found to bediprotic acids, while pyrite was determined to be a triprotic acid. Intrinsic acidity con-stants for the four minerals are as follows: chalcocite-pK_(a1)=5.25, pK_(a2)=9.68;galena- pK_(a1)=5.26, pK_(a2)=9.62; sphalente- pK_(a1)= 5.08, pK_(a2)= 9.13;and pyrite - pK_(a1) = 3.50,pK_(a2)=5.32, pK_(a3)=9.81.

乙二醇锑中锑含量分析方法比较

介绍了聚酯催化剂乙二醇锑中锑含量分析方法,从分析技术原理、实验设备材料、影响因素、经济适用性等方面进行了对比分析。对比结果表明,3种分析方法适用于不同的分析条件,不同的生产企业和检测单位可以根据自身的需要建立适合自己企业的分析方法。文章的研究内容对聚酯催化剂乙二醇锑中锑含量分析方法的选择具有一定的指导意义,可为相关领域的研究提供一定的参考。

流动注射法检测枸杞中二氧化硫残留量的方法比较及风险评估

近年来自动化检测设备以及对应方法相继涌现,本研究使用在线蒸馏-流动注射法与国标中酸碱滴定法、离子色谱法对枸杞中二氧化硫残留量进行检测比较。结果表明,三种方法的测定结果并无显著性差异。在线蒸馏-流动注射法RSD在1.5%~2.4%之间,加标回收率在86.1%~92.7%之间,因其具有自动化程度高、检测周期短的优势,更适合大批量样品的快速准确检测。用在线蒸馏-流动注射法对106批次红枸杞中的二氧化硫残留量进行检测分析,并对枸杞中的二氧化硫残留量进行暴露风险评估。结果显示,二氧化硫超标率达21.7%,枸杞中二氧化硫残留尚未对健康构成威胁。

自动化学滴定仪在冶金分析中的应用

介绍了一种自动化学滴定仪的分析原理和实验方法。以重铬酸钾滴定分析铁矿石中全铁含量为例,通过与传统化学容量法比较,得出该自动化学滴定仪在冶金分析中具有精密度和准确度高、滴定速度可控及滴定分析误差小等优点。

3种测定广式酱油中总糖含量的方法比较

该研究通过比较直接滴定法、苯酚硫酸法、蒽酮硫酸法3种方法测定广式酱油总糖含量的差异,并对这3种方法进行方法学验证,以期筛选出一种适合广式酱油总糖含量测定的方法。结果显示,直接滴定法、苯酚硫酸法和蒽酮硫酸法分别在0.50~8.00、0.00~0.08和0.00~0.08 mg/mL范围内线性关系良好。直接滴定法、苯酚硫酸法和蒽酮硫酸法的精密度试验的RSD值分别为1.07%、0.05%、0.05%,重现性试验的RSD值分别为0.88%、3.93%、3.24%,直接滴定法在24 h内显色稳定,苯酚硫酸法和蒽酮硫酸法在1 h内显色稳定。而在加标回收率试验中,蒽酮硫酸法的平均加标回收率较高,为168.04%,RSD值为2.97%,直接滴定法的平均加标回收率为104.67%,RSD值为2.07%,苯酚硫酸法的平均加标回收率为103.85%,但其RSD值为8.04%,蒽酮硫酸法测定酱油总糖含量的准确度低于其他两种方法。因此,直接滴定法和苯酚硫酸法的精密度、重现性、稳定性良好,理论上均具有可行性,蒽酮硫酸法不适合用于广式酱油总糖含量的测定。酱油中总糖含量是反映酱油品质的基本指标之一,筛选出适合酱油总糖含量的检测方法,对实际酱油生产监控和产品加工过程的品质控制都有重要意义,同时也为酱油总糖含量测定方法标准的制定提供一定的实验参考。

锗元素测定方法综述

锗在国防工业、航空航天和通信等领域中具有战略性意义,锗含量的测定对于保证材料质量和满足国际标准至关重要。对锗含量测定方法的多种技术进行了综述,包括分光光度法、原子荧光光谱法、原子吸收光谱法、电感耦合等离子体原子发射光谱法、电感耦合等离子体质谱法以及滴定法等。在每种检测方法的介绍中,详细探讨了方法的原理、前处理步骤以及应用范围,并分别总结了各方法的优势和不足。最后,强调了锗含量测定方法的意义,特别是在满足出口监管和促进科学研究方面的作用。同时对锗元素的测定方法进行了展望,为未来的发展提供了参考方向。

厨余垃圾干式厌氧发酵过程中的挥发性脂肪酸测定方法研究

在厨余垃圾干式厌氧发酵过程中,挥发性脂肪酸浓度是一个重要的监测指标,通过每天测定挥发性脂肪酸浓度可以了解厌氧发酵系统的运行情况。分别采用Nordmann滴定法、气相色谱法和比色法测定了厨余垃圾干式厌氧发酵过程中挥发性脂肪酸的浓度。试验结果表明,由于比色法待测样品预处理过程较多等原因,导致采用比色法测定挥发性脂肪酸浓度的结果较不稳定。气相色谱法操作繁琐、样品预处理过程较多,单个样品试验时间较长,适用于需要测定单种挥发性脂肪酸浓度的情况。Nordmann滴定法能够克服这些缺点,兼具有操作简单、精密度高等优点,因此建议厨余垃圾厌氧发酵过程中挥发性脂肪酸的浓度优先使用Nordmann滴定法进行测定。

仪器法和手工法测定水源水和生活饮用水中高锰酸盐指数的对比研究

利用高锰酸盐指数全自动分析仪和手工滴定法对国家标准物质、水源水和生活饮用水中实际样品进行比对,比较了两种方法的检出限、精密度、准确度、加标回收率等,且分别考察了氯离子对高锰酸盐指数测定的干扰。结果表明,两种方法的标准样品测定值均在标准值允许范围内,且精密度好、准确度高,均能满足水源水和生活饮用水中高锰酸盐指数的检测需要。

含油食品酸价检测不确定度评定

酸价是反映食品中油脂酸败程度的重要指标,也是食用油或含油食品中必检项目之一。酸价检测不确定度评定可以更科学地评价酸价检测的准确性、科学性和公平性。本文采用冷溶剂指示剂滴定法与冷溶剂自动电位滴定法检测酸价,建立数学模型,分析不确定度来源,评定各不确定度分量、合成不确定度及扩展不确定度。结果表明,自动电位滴定法检测某含油食品酸价结果为6.4 mg/g,扩展不确定度为0.2 mg/g,K=2,显著性不确定度分量为NaOH标准滴定液浓度;指示剂滴定法酸价为6.3 mg/g,扩展不确定度为0.3 mg/g,K=2,显著性不确定度为NaOH标准滴定液浓度不确定度最大、A类不确定度次之、滴定体积不确定度再次之,且三者显著性相近,扩展不确定度大于电位滴定法。通过不确定度评定和显著性分析,可以有针对性地找到降低或控制检测误差的方法,提高检测结果准确性。

水蛭抗凝活性检测两种滴定方法比较

目的:比较药典标准凝血酶滴定法和白瓷板法对中药水蛭抗凝活性检测结果的影响。方法:分别采用《中国药典》中凝血酶滴定法和云南省《菲牛蛭冻干粉中药饮片炮制规范征求意见稿》中白瓷板法对水蛭抗凝活性进行多次平行滴定实验。结果:抗凝活性成分含量较高的菲牛蛭其药典法滴定结果重复性更稳定,白瓷板滴定法结果的重复性会随着单次进样量减少而趋于稳定;宽体金线蛭的抗凝活性结果在两种方法的对比检测下均较为稳定。结论:对于吸血水蛭品种抗凝活性的测量,建议保留原凝血酶滴定法;对于抗凝活性较低,实验中凝血酶溶液浓度较小的水蛭品种,两种滴定法均适用,也可同时应用互相验证。另在滴定操作中,将反应试管改换成玻璃液相进样瓶,且在滴定动作后将反应容器呈一定角度倾斜放置,有助于对反应终点进行判断,提高实验结果的准确性和稳定性。

阳离子表面活性剂中活性物测试方法综述

目前阳离子表面活性剂活性物测定方法主要有两相滴定法、胶体滴定法、电位滴定法和液相色谱法等。综述各种测试方法的原理、测试现象等,并对各分析方法的适用范围、优点和缺点进行比较,为阳离子表面活性剂生产、研发过程中选取适当的测定方法提供参考。

两种测定阿司匹林肠溶片含量的方法在教学应用中的比较

测定阿司匹林肠溶片含量是药物分析实验的核心教学内容。两步酸碱滴定法和高效液相色谱法是教学实验中最常用的两种方法,本研究从实验原理、方法、实验设施和教学实践能力等多个方面进行比较。两步酸碱滴定法具有实验操作容易、所需实验设备较少,但测定结果不够准确的特点。高效液相色谱法测定结果准确,且可以提升学生使用高效液相色谱的能力。但其实验过程复杂,对实验场地和经费具有较高要求。最后提出以两步酸碱滴定法为基础教学内容,将高效液相色谱法作为拓展内容。在理解阿司匹林肠溶片含量测定原理和方法同时,提升学生应用现代药物分析设备的能力,有助于提高人才培养水平。

表面活性剂和pH值对脂肪酶活力稳定性的影响

采用滴定法探究pH值、阴离子表面活性剂、非离子表面活性剂和两性表面活性剂对脂肪酶活力稳定性的影响。结果表明,脂肪酶在碱性条件下酶活力较好,当pH=8且表面活性剂溶液质量分数为10%时,两性表面活性剂椰油酰胺丙基二甲基氧化胺(CAO)对脂肪酶活力影响最小,十二烷基苯磺酸钠(SDBS)对脂肪酶活力影响最大,将CAO与脂肪醇聚氧乙烯醚硫酸酯钠(AES)在不同pH值下复配,结果表明,当AES与CAO复配比例为1∶1时,在pH=7.5条件下高温4周的脂肪酶活力仍可保持在98.6%。