Determination of sodium sulfate in anionic surfactants by nonaqueous titration

A convenient and easy method was developed for nonaqueous titrimetric determination of sodium sulfate in the presence of sulfonate and sulfate type anionic surfactants. Sodium sulfate and the anionic surfactants were converted to sulfuric acid and the corresponding organo-sulfonic or organo-sulfuric acids by the addition of an excess of perchloric acid. The resulting acid mixture was then titrated in methanol with cyclohexylamine. The sulfate content was calculated from the difference of the two end points of the differentiating titration curve. For the determination of sodium sulfate in typical anionic surfactants, the relative standard deviation varied from 0.7 to 2.0% at the 0.3-10% sodium sulfate levels. The method provides a rapid and precise determination of inorganic sulfates in sulfonated or sulfated materials.     

串联式压电传感器测定水中阴离子表面活性剂

基于阴离子表面活性剂与季铵盐反应前后电导的改变和压电传感器能响应溶液电导率的性质,建立了串联式压电传感器测定水中阴离子表面活性剂的新方法。在５００μｇ氯化十六烷基吡啶存在下,十二烷基磺酸钠的浓度在３．６×１０－７～５．７×１０－５ｍｏｌ·Ｌ－１范围内与压电传感器的频移值呈线性关系,相关系数为０．９９８９,检测下限为１．７×１０－７ｍｏｌ·Ｌ－１。用此法测定了环境水样中的阴离子表面活性剂,其加标回收率为９４．４％～１００．２％,相对标准偏差小于４．９％     

Methyl Orange Paired Microextraction and Diffuse Reflectance‐Fourier Transform Infrared Spectral Monitoring for Improved Signal Strength of Total Mixed Cationic Surfactants

We report a novel methyl orange paired microextraction (MOP‐ME) and diffuse reflectance‐Fourier transform infrared (DRS‐FTIR) spectral monitoring for improved signal strength of total mixed cationic surfactants (CS⁺) for its quantification in real water samples. To the best of our knowledge, this is the first report that describes the rapid quantitative determination of total mixed CS⁺ using MOP‐ME/DRS‐FTIR. The method is based on separation and preconcentration of CS⁺ using chloroform as the extracting solvent by the formation of ion‐pair complex with anionic methyl orange (MO^?) followed by DRS‐FTIR analysis. The intense vibration peak obtained at 2919 cm^?1 in the FTIR spectra was used for the optimization of all analytical parameters and for the determination of mixed CS⁺. The best extraction efficiency of CS⁺ from the aqueous solution was obtained at pH 4.0 when extracted for 3 min in chloroform at a stirring rate of 250 rpm. The linearity range obtained for the determination of total mixed CS⁺ in water sample was 0.150–300 μg L^?1 with the limit of detection and limit of quantification as 0.05 and 0.150 μg L^?1, respectively. The good recovery percentage (97.1–109.5%) from wastewater showed that the method is very selective for the determination of total CS⁺ in complex sample matrices. The advantages of the MOP‐ME/DRS‐FTIR method are its simplicity, selectivity, and sensitivity toward the analysis of total mixed CS⁺ in wastewater samples.     

Liquid scintillation determination of surfactants on cotton fabric

A method for the determination of anionic surfactants on cotton fabric has been developed using S³⁵ and H³ labelled compounds. The method is simple, involving immersion of the white fabric in liquid scintillation counting solution and counting. No interference by quenching or self-absorption is encountered. Accuracy and precision are better than ±2% relative. Replacing the internal standard method by the pulse height shift method of obtaining disintegration rates simplified the analysis and increases its precision. Combination of the pulse height shift method with automatic data handling has permitted the analysis of several hundred samples per week with little increase in operator time.     

离子色谱法在盐碱分离中测定氯离子的应用

为了准确快捷了解盐碱分离过程中氯化钠含量,引入离子色谱法对氯离子浓度进行分析。建立了碱矿脱盐过程中对氯离子的离子色谱分析方法,选用Shodex阴离子色谱分析柱、碳酸钠溶液为淋洗液、电导检测器检测。在实验中,测试了碱液中碳酸钠和碳酸氢钠对氯离子测定的影响并得出测定碱液中氯离子的标样条件,以及通过对淋洗液改进(浓度、流速、有机试剂)缩短出峰时间,最优化条件能使之从11.682 min缩短到8.367 min。该方法具有良好的精密度,相对标准偏差为0.89%(n=6),加标回收率为98.73%。     

Application of Micellar Extraction for Isolation of Famotidine from Aqueous Samples Prior to its Chromatographic Determination

Micellar extraction was applied to isolate famotidine from aqueous samples. This drug is an H₂ receptor antagonist used for the treatment of stomach diseases. The process was performed with a mixture of anionic sodium dodecylsulfate and nonionic Triton X‐114 surfactants. The effect of different parameters on the efficiency of the micellar extraction such as electrolyte and surfactant concentration, pH of sample, temperature, shaking and centrifugation time was investigated. The influence of foreign substances on a studied process was tested. The elaborated procedure was applied for HPLC–UV determination of famotidine in natural water samples. The calibration graph was recorded in the range 1.35–37.12 μg mL^?1 of the studied compound. The repeatability of the method was equal to 7.4%. The limit of detection and quantification values for the determination of famotidine by using the proposed method amounted to 0.40 and 1.25 μg mL^?1, respectively.     

Use of surfactants and blends to remove DDT from contaminated soils

Removal of dichloro‐diphenyl‐trichloroethane (DDT) from soils using surfactant‐enhanced solubilisation was studied both in batch and continuous flow arrangements to determine if there were advantages to using a combination of non‐ionic (Tween and Brij) and anionic surfactants. It was observed that the presence of the anionic surfactant sodium dodecyl benzene sulphonate improved the DDT removal efficiency, but had a potentially negative effect on flow rates in column leaching experiments at concentrations over 0.1%. The potential for re‐use of the surfactant mixture was studied and demonstrated by removing DDT and its metabolites from the surfactant solution using activated carbon. © 2011 Canadian Society for Chemical Engineering     

Development of an Ultraviolet‐Spectrophotometric Method for Analysis of Esterquat‐Containing Flotation Collectors in Aqueous Solutions

In this study, a rapid and simple ultraviolet‐spectrophotometric method was developed and validated for the quantitative determination of esterquat‐containing flotation collector FLOT 2015 in aqueous solutions. This method is based on the formation of an ion pair by FLOT 2015 and bromocresol purple, an anionic dye, and the subsequent measurement of the reduction in absorbance without extraction by organic solvents. The optimum conditions for FLOT 2015 detection and analysis were established. Sample solutions were stable up to 3 h. Maximum absorbance was obtained at 574 nm. The proposed method showed linearity in the range of 5–45 μg mL^?1 with a correlation coefficient of 0.9917. Standard and relative standard deviation obtained by intraday and interday precision tests of the proposed method were within the permissible bias range and considered satisfactory. This method was found to be selective and specific for successful determination of FLOT 2015 in aqueous flotation systems.     

亚甲蓝分光光度法测定阴离子表面活性剂的改进

亚甲蓝分光光度法（GB7494-87）的操作流程过于繁琐,样品分析耗时耗力,现进行简化改进,旨在建立一种简便、快速的测定水中阴离子表面活性剂的方法。     

A Highly Efficient Automated Flow Injection Method for Rapid Determination of Free Fatty Acid Content in Corn Oils

In the present study, a new flow injection (FI) methodology for determination of free fatty acid (FFA) content in corn oil samples is proposed. The proposed method is based on monitoring the absorbance changes at 580 nm, λ_max, as a result of neutralization of FFA in oil samples by KOH in the reagent. The analyses were performed with a single‐line FI manifold system created by modification of high performance liquid chromatography. The main parameters, such as sample and reagent volumes, reaction coil, reagent concentration and temperature were all optimized. With the newly developed sampling strategy, the oil sample and reagent at micro level were directly injected together without any pre‐treatment. The proposed flow injection analysis method was validated statistically and it was found to be linear (between 0.09 and 1.50 FFA %), accurate (recovery 87.19–122.22 %), and precise (relative standard deviation <1 % for both intra‐day and inter‐day precision). The limit of detection and limit of quantification were found to be 7.41 × 10^?3 and 2.24 × 10^?2 oleic acid %, respectively. The results were also compared with those obtained by the American Oil Chemists Society (Ca‐5a‐40) method using statistical t and F tests, and a significant difference was not observed between the methods at the 95 % confidence level. These results strongly suggest that this method is suitable for automated routine analysis of FFA in edible oils due to its simplicity, reliability, speed, and economy of solvents and sample.     

连续流动注射法测定水中阴离子表面活性剂的不确定度评定

对流动注射法测定水中阴离子表面活性剂的不确定度进行分析,找出影响不确定度的主要因素,对不确定度进行研究,给出合成标准不确定度和扩展不确定度。     

A New Sensor for Determination of Anionic Surfactants in Detergent Products with Carbon Nanotubes as Solid Contact

A new solid‐state sensor for potentiometric determination of surfactants with a layer of multi‐walled carbon nanotubes was prepared. As a sensing material, 1,3‐didecyl‐2‐methylimidazolium–tetraphenylborate ion‐pair was used. The investigated sensor showed a Nernstian response for both dodecylbenzenesulphonate (DBS, 57.6 mV/decade of activity between 5 × 10^?7 to 1 × 10^?3 M) and sodium lauryl sulfate (LS, 58.4 mV/decade of activity between 2 × 10^?7 to 2 × 10^?3 M). It responded in 8–10 s for each ten‐fold concentration change in the range of 1 × 10^?6 to 3 × 10^?3 M. The detection limits for DS and DBS were 2 × 10^?7 and 3 × 10^?7 M, respectively. The sensor revealed a stable response (signal drift 2.6 mV/h) and exhibited satisfactory selectivity performances for LS over most of the anions generally used in surfactant‐based commercial detergents. The main application of this sensor was the end‐point determination in potentiometric titrations of anionic surfactants. The (diisobutyl phenoxy ethoxy ethyl)dimethyl benzyl ammonium chloride (Hyamine), cetyltrimethylammonium bromide, hexadecylpyridinium chloride monohydrate (HDPC) and 1,3‐didecyl‐2‐methylimidazolium chloride were tested as potential cationic titrants, and all exhibited analytically usable titration curves with well‐defined equivalence points. The standard solution of HDPC was used as a cationic titrant by all potentiometric titrations. The operational life‐time of the sensor described was prolonged to more than 3 months.     

The Effect of Counterions of Linear Alkylbenzene Sulfonate on Skin Compatibility

Interactions of a widely used commercial anionic surfactant, linear alkylbenzene sulfonate, with zein protein, a water insoluble protein, was studied to better understand the effects of the counterion on skin irritation of anionic surfactants. The neutralizing ions used were inorganics: Li⁺, Na⁺, K⁺, Mg²⁺, and NH₄⁺ and organics: monoethanolamine, diethanolamine, and triethanolamine. According to the results obtained, the influence of counterions of anionic surfactants on zein solubilization is significant; with magnesium counterions showing lower zein solubilization. In aqueous solutions, zein solubilization by anionic surfactant is related to the effect of the counterion on the critical micelle concentration of the surfactant for the inorganic counter‐ions; for the organic counter‐ions, effects of tighter anionic binding in the micelle also contribute to zein solubilization trends.     

混合指示剂单相滴定法测定烷基磷酸酯钾盐

本研究用混合指示剂单相滴定法测定ISO标准方法所不能测定的磷酸盐阴离子表面活性剂的浓度.测定PK、E502A、昆山PK的常数K分别为355.lg/M、420.7g/M和344.0g/M,变异系数分别为1.45%、0.59%和1.26%,测定实际试样的加标回收率为98.2～103.9%.方法准确、简单、快速,不需用毒性较大的有机溶剂,本法适用于化纤油剂和涤纶短纤维上油率等的测定.     

Adsorption of surfactants from water onto raw and HCl-activated clays in fixed beds

The removal of surfactants from water by adsorption onto raw and HCl-activated montmorillonite in fixed beds was studied. Three surfactants hexadecylpyridinium chloride (cationic), sodium dodecyl sulfate (anionic), and Triton X-102 (non-ionic) were selected in the concentration ranges lower than their critical micelle concentrations in fixed bed experiments. It was shown that the adsorption of anionic surfactant onto Ca-montmorillonite (SAz-1) decreased with increasing pH but that of cationic surfactant increased. The adsorption capacity of non-ionic surfactant was maximized at pH 7.0. For given clay, the adsorption capacities of surfactants were strongly pH-dependent. The adsorption capacity and adsorption rate of non-ionic surfactant onto SAz-1 could be largely improved after acid activation of the clay. Such an improvement was due to the fact that the dissolution of Al³⁺ or Fe²⁺ of montmorillonite occurs in acid solution. The calculated breakthrough curves in fixed bed agreed with the measured ones (standard deviation < 6%). The 50% C/C₀ breakthrough time (τ) decreased with increasing liquid flow rate. The effects of flow rate on the adsorption constant and adsorption capacity were also discussed.     

Simple chemical polymerization method for the deposition of a conducting polyaniline on the surface of acrylonitrile–butadiene–styrene. II. Treatment in organic free solvent

We developed a simple method for the deposition of a uniform layer of polyaniline (PANI) on the surface of acrylonitrile–butadiene–styrene (ABS). The method consisted of two steps: the soaking of ABS samples in a water‐based aniline solution stabilized by surfactants followed by the oxidative polymerization of the adsorbed and absorbed monomer. The three types of surfactants (molecular N,N‐dimethyl‐octalamine‐N‐oxide, anionic sodium dodecyl sulfate, and cationic hexadecyl trimethyl ammonium bromide) were used to prepare and stabilize the aniline emulsions in water. After treatment, the ABS surface was completely covered by PANI (as seen with scanning electron microscopy). The surface conductivity after PANI coating reached values between 10^?3 and 10^?4 S/□ in the best developed conditions. The chemical nature of the surfactant affected the particular setting of the aniline/surfactant emulsion preparation (time of ultrasonification = 15–30 min), its optimal concentration (2–10 wt % aniline and 0.1–0.2M surfactant), and other parameters of treatment, such as time (10 s to 20 min) and temperature (20–60°C) of soaking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1752–1758, 2004     

水中阴离子表面活性剂测定方法概述

简要介绍了表面活性剂的性质,阴离子表面活性剂的种类及其对水体环境的危害;重点对水中阴离子表面活性剂的测定方法即分光光度法、两相滴定法、高效液相色谱法、薄层层析法及离子选择性电极分析法等进行了综述;提出了水中阴离子表面活性剂测定方法向信息化、实时快速在线监测智能化和检测仪器向微型化的方向发展。     

Efficient and Response Surface Optimized Aqueous Enzymatic Extraction of Camellia oleifera (Tea Seed) Oil Facilitated by Concurrent Calcium Chloride Addition

This paper reports an efficient aqueous enzymatic extraction (AEE) method for Camellia oleifera seed oil with the aid of response surface analysis. A maximum oil recovery of ~93.5% was obtained when a 2‐step AEE process was performed using 0.80% cellulase (v/w) solution at pH 6.0 maintained at 50 °C for 1 h followed by a solution of 0.70% Alcalase® with pH 9.2 at 57 °C for 4.1 h. It was found that the addition of Ca²⁺ during the proteolysis stage improved the free oil yield from ~62.1 to ~86.6%. This was attributed to the removal of tea saponins, cross‐linkage of anionic polysaccharides, and destabilization of cream emulsion by Ca²⁺. This was verified by decreased tea saponin and polysaccharide levels in the cream emulsion and bulk solution as well as lowering of the emulsion fraction. It was determined that addition of CaCl₂ solution in continuous flow to the proteolysate is superior to one‐time or batch addition in inhibiting emulsion formation. The addition of CaCl₂ may provide a means of replacing the more laborious, time‐consuming demulsification process otherwise required.     

Determination of Copper,Iron, Nickel,and Zinc in Ethanol Fuel by Flame Atomic Absorption Spectrometry Using On‐Line Preconcentration System

Abstract

In this work, an on‐line system for preconcentration and determination of copper, iron, nickel, and zinc at µg L^?1 level by flame atomic absorption spectrometry (FAAS) has been developed. Amberlite XAD‐4 functionalized with 3,4‐dihydroxybenzoic acid packed in a minicolumn was used as metal sorbent. The retained metals can be quickly eluted from sorbent material, with the eluent stream consisting of hydrochloric acid solution, directly to the nebulizer burner system of the FAAS. Analytical parameters were evaluated and the results demonstrated that all studied metals can be determined, using borate buffer to adjust the sample pH at 8.0. The results showed that the proposed method is simple and rapid. The limits of detection were estimated as 2.3, 5.0, 7.8, and 0.1 µg L^?1 for copper, iron, nickel, and zinc, respectively, using a preconcentration time of 60 s and a sample flow rate of 5.5 mL min^?1. Enrichment factors of 22, 15, 12, and 54 and coefficients of variations of 3.5, 4.4, 4.4, and 3.2% were obtained in the determination of copper, iron, nickel, and zinc, respectively. The system presented an analytical throughput of 10 samples per hour and was successfully applied in the determination of metals in ethanol fuel.     

SKALAR San++连续流动分析仪同时检测水源水中总氮和总磷

实验建立了采用SKALAR San++连续流动分析仪同时检测水源水中总氮和总磷的分析方法,其中总氮方法检出限为0.05 mg/L,纯水加标回收率为94.0%~104%,相对标准偏差RSD为0.0%~0.07%;总磷方法检出限为0.009mg/L,纯水加标回收率为91.0%~106%,相对标准偏差RSD为0.0%~0.7%,均符合工作要求。通过对比分析,该方法较传统手工方法具有明显优势:可以直观图谱查看结果,可以连续监测水源水中总氮和总磷的变化,实现快速检测,对提高水源水质监测预警具有重要意义。