Rapid determination of anionic surfactants in an aqueous medium by the ionassociation titration method coupled with a streaming potential detector

An ion-association titration method coupled with a streaming potential detector was developed for the determination of anionic surfactants in a one-phase aqueous system. The titrant, benzethonium chloride (Hyamine) ion, was added to an anionic surfactant solution. The potential then changed from negative to positive along with an increase in the added titrant. The end point was read from an inflection point of a diffrential curve. The usual samples were titrated within 10 min. Anionic surfactants at concentrations from 10(-5)10(-3) mol dm(-3) could be determined by the proposed method. The relative standard deviations of various anionic surfactants were 0.20.6%. The proposed method was applied to the determination of various anionic surfactants and anionic surfactants in commercial detergents. The results obtained for practical samples were in good agreement with those of the JIS titration method (Epton method).新しい流動電位検出器を用いたイオン会合滴定法による陰イオン界面活性剤の迅速定量法を開発した.陰イオン界面活性剤を陽イオン界面活性剤で滴定すると, 流動電位が負から正に変化することを用いて終点検出を行うという非常に簡単なもので, 更にクロロホルム溶媒を用いない水溶液系という特徴を有する.測定条件の最適化を行い, 10(-5)～10(-3)Mの濃度範囲の陰イオン界面活性剤を相対標準偏差0.2～0.5%と高精度で, 迅速自動定量 (10分/件) できることが分かった.陰イオン界面活性剤の各種標準及び実際試料について応用した結果, 定量値はJIS法 (Epton法) と非常に良い一致を示した

Rapid determination of cationic surfactants in an aqueous medium by the ionassociation titration method coupled with a streaming potential detector

An ion-association titration method coupled with a streaming potential detector was developed for the determination of cationic surfactants in a one-phase aqueous system. Dodecyl sulfate ion (LS-) was used as a titrant for cationic surfactants in a direct titration method. LS- was added to a cationic surfactant solution, and a potential change from positive to negative was observed. The end point was read from an inflection point of a differential curve. Direct and indirect titration methods for the determination of cationic surfactants were examined. The direct titration method was better than the in- direct titration method with respect to the precision. The usual samples were titrated within 10 min. Cationic surfactants at concentrations from 10-510-3 mol dm-3 could be determined by the proposed method. Amine and quaternary ammonium salts could be determined under both acidic and alkaline conditions. The proposed method was applied to the determination of various cationic surfactants and cationic surfactants in commercial detergents. The results obtained by the proposed method were in good agreement with those of the JIS titration method (Epton method).流動電位検出器を用いたイオン会合滴定法による陽イオン界面活性剤の迅速定量法を開発した.本法は, 陽イオン界面活性剤を陰イオン界面活性剤で滴定するもので, 流動電位が正から負に変化することを利用して終点検出を行うものである.検出原理及び装置は非常に簡単なもので, 従来のクロロホルム溶媒を用いない水溶液系で行うことができる.10(-5)～10(-3)Mの濃度範囲の陽イオン界面活性剤を迅速自動定量 (10分/件) できる.直接滴定法と逆滴定法について検討した結果, 直接滴定法のほうが逆滴定法に比べて再現性の面で優れていることが分かった.陽イオン界面活性剤の各種標準及び実際試料の応用について検討した結果, 分析値はJIS法 (Epton法) と非常に良い一致を示し, 再現性も良好であった.更に, 酸性及びアルカリ性条件下での測定により, アミン塩及び四級アンモニウム塩の分別定量も可能となった

Automatic determination of ionic surfactants in an aqueous medium by a photometric titration method

A fully automatic photometric titration method was developed for the determination of anionic and cationic surfactants in a one-phase aqueous system with tetrabromophenolphthalein ethyl ester (TBPE) used as an indicator. To avoid decomposition of the TBPE indicator in the presence of an anionic surfactant in acidic solutions, the buffer and indicator solutions were automatically added to sample solutions just before titration. In an indirect titration method for cationic surfactants, cationic surfactants were automatically determined under the same conditions as in the titration of anionic surfactants. The usual samples were analyzed for less than 10 min at concentrations of 10(-6)10(-3) mol dm(-3). The relative standard deviations of the determination of various surfactants were 0.20.3%. The proposed method was applied to many practical samples. The results, except for those for anionic surfactants possessing polyoxyethylenyl groups and several cationic surfactants, were in good agreement with the results obtained by the JIS titration method (Epton method).微分光度滴定法を用いて,水溶液でのイオン性界面活性剤の自動分析システムの構築について検討した.滴定終点決定の指示薬であるテトラブロモフェノールフタレインエチルエステル(TBPE)は界面活性剤との共存系では経時的に分解するため滴定直前に自動添加すること,及び陽イオン界面活性剤は逆滴定法の採用により自動化システムを構築し,同一条件下で陰イオン及び陽イオン界面活性剤の自動連続定量(10分/件)が可能となった.本滴定法で10(-6)～10(-3)Mの濃度範囲の陰イオン及び陽イオン界面活性剤が定量でき,再現性は0.2～0.3%と良好であった.各種実際試料について応用した結果,陰イオン界面活性剤において,一部の親水性の高い活性剤(オキシエチレン基を特に多数含む活性剤)以外はJIS法(Epton法)と非常に良い一致を示し,又陽イオン界面活性剤においても,JIS法とほぼ一致した

Determination of anionic surfactants in an aqueous medium by differential photometric titration method

微分光度滴定装置を用いて,水溶液での陰イオン界面活性剤を定量する方法について検討した.滴定終点決定の指示薬系としては,酸性染料のテトラブロモフェノールフタレインエチルエステル(TBPE)と非イオン界面活性剤のTriton X-100(TX-100)の混合溶液を用いた.TBPEは非イオン界面活性剤の存在下で,酸性では黄色となり可溶化しているが,滴定剤の第四級アンモニウムイオンと反応するとイオン会合体を形成し,解離型(TBPE-)の青色(λ(max)=610nm)となる.滴定剤には第四級アンモニウム塩のジステアリルジメチルアンモニウム・クロリド(DSDMA(+)・Cl(-))を用いた.本滴定法で10(-6)～10(-3)Mの濃度範囲の陰イオン界面活性剤が定量できる.実際試料の定量結果はオキシエチレン基を持つもの以外の試料において,JIS滴定法(JIS K 3362)及びエチルバイオレット抽出吸光光度法(JIS K 0101)とよく一致した.A simple and rapid automatic photometric titration method was developed for the determination of anionic surfactants in a one-phase aqueous system with tetrabromophenolphthalein ethyl ester (TBPE) as an indicator. In the presence of non-ionic surfactants such as Triton X-100, protonated TBPE reacts with cation (Q(+)) to form an ion associate (Q(+)·TBPE(-)), causing a color change from yellow to blue. The titrant, distearyldimethylammonium ion, was added to an anionic surfactant solution at pH 3.2, and the absorbance changes were monitored by a fiber-optic sensor with a 630 nm interference filter. The end points were read from the inflection points with differential curves. Anionic surfactants at concentrations from 10(-6)10(-3) mol dm(-3) could be determined by the proposed method. The relative standard deviations of various anionic surfactants were 0.30.4%. The proposed method was applied to some practical samples, and the results, except for those of anionic surfactants possessing polyoxyethylenyl groups, were in good agreement with the results of the JIS titration method (Epton method) and a solvent extraction method with Ethyl Violet