کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1172246 | 1491178 | 2006 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Measuring quaternary ammonium cleaning agents with ion selective electrodes Measuring quaternary ammonium cleaning agents with ion selective electrodes](/preview/png/1172246.png)
Data for coated-wire, ion selective electrodes (ISEs) are presented for cationic surfactant ions found in common cleaners including benzyldimethyltetradecylammonium, benzyldimethyldodecylammonium, and benzyldimethylhexadecylammonium. The ion exchangers dinonylnaphthalene sulfonic acid, tetraphenyborate, and tetrakis(4-chlorophenyl)borate are examined, showing dinonylnaphthalene sulfonic acid to be the favored species. The ISEs exhibit approximately Nernstian behavior down to the 10−6 M limit of detection with lifetimes in excess of 50 days when used continuously, and a shelf life of over 100 days. Reaching the upper detection limit at the critical micelle concentration requires use of polymeric-membrane reference electrodes including a new membrane cocktail, which allow response measurements of an order of magnitude higher than the traditional fritted-glass reference electrode. The surfactant ISEs show excellent selectivity over the common metal ions Na+, K+, Mg2+, Ca2+, and Cu2+ with selectivity coefficients less than 10−5.3. The ISEs are also selective over the lower molecular weight quaternary ammonium ions tetradecyltrimethylammonium, dodecyltrimethylammonium, benzyldimethyl(2-hydroxyethyl)ammonium, and tetrabutylammonium with selectivity coefficients ranging from 10−1.7 to 10−5.5. Use of a single electrode to determine accurately the total cationic surfactant concentration in common cleaning solutions is accomplished with information about concentration dependent interferences and a modified Nikolsky–Eisenman model. Finally, quaternary ammonium surfactants have a deleterious effect on the measurements of pH and common ions like K+, Mg2+ and Ca2+ with polymeric ISEs. This makes it critical to include surfactant electrodes in a detector array when cleaning agents are present.
Journal: Analytica Chimica Acta - Volume 570, Issue 2, 16 June 2006, Pages 186–194