利用荧光素异硫氰酸酯检测季铵盐阳离子表面活性剂的方法

Concentration characterization of quaternary ammonium surfactants by FITC

使用荧光素异硫氰酸酯(FITC)实现了对季铵盐阳离子表面活性剂(QAS)在水溶液中临界胶束浓度(CMC)的准确测量及其在CMC以下的浓度定量。用该法测得十二烷基三甲基溴化铵(DTAB)和十六烷基三甲基溴化铵(CTAB)在水中的CMC分别为12～13mmol·L-1和0.70～0.96mmol·L-1,与电导率法、表面张力法和芘荧光法的检测值相近。对DTAB和CTAB的检测下限分别是0.11mmol·L-1和1.7μmol·L-1,定量范围分别为0.11～9.73mmol·L-1(0.034～3.0g·L-1)和1.7μmol·L-1～0.27mmol·L-1(6.2×10-4～0.1g·L-1)。结果表明,使用FITC荧光探针检测QAS具有安全、简便、灵敏度和准确度高的优点。

Quaternary ammonium surfactants （QAS） are one of the most important surfactants in industry, pharmaceuticals and cosmetics. Their rapid detection and accurate quantification plays a key role in controlling their application or existence in the environment. In the present study, a novel method was established to detect the critical micelle concentration （CMC） of QAS in water and to quantify the surfactant concentration below its CMC, based on the fluoro-spectrum and fluorescence intensity change of fluorescein isothiocycanate （FITC） . This approach was simple and sensitive, achieving the limit of detection （LOD） of dodecyltrimethylammonium bromide （DTAB） and cetyltrimethylammonium bromide （CTAB） at 0. 11 mmol·L^-1 and 1.7 mmol·L^-1, respectively. And the quantification range of DTAB and CTAB was 0.11--9. 73 mmol·L^-1（0.034- 3.0 g·L^-1） and 1. 7mmol·L^-1-0.27 mmol·L^-1 （6.2× 10 ^-4 -0. 1 g·L^-1） , respectively. The CMCs were detected as 12--13 mmol·L^-1 （DTAB） and 0.70-- 0.96 mmol·L^-1 （CTAB）, which were consistent with the results measured by the conductance, surface tension of the solution or by the pyrene probe. Concentration characterization of the QAS-water solution by FITC has provided a new, safe, simple and accurate approach to analyzing and monitoring the surfactants in the environment or in their wide application.