کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9748719 1493790 2005 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Assessment of supporting electrolyte contributions in electrochemically modulated liquid chromatography
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Assessment of supporting electrolyte contributions in electrochemically modulated liquid chromatography
چکیده انگلیسی
This paper reports the results of an investigation on the role of the supporting electrolyte in separations using electrochemically modulated liquid chromatography (EMLC) with a porous graphitic carbon stationary phase. With respect to the identity of the supporting electrolyte, the elution strength of the electrolyte anion increased as F− < OH− < BF4− < ClO4− < PF6− for injections of negatively charged aromatic molecules, whereas a 10-fold increase in electrolyte concentration induced a 60% change in retention for the same solutes. Furthermore, both the concentration and composition of the supporting electrolyte affected retention in a manner that varied with the charge of the analyte and applied potential. This behavior is explained using Gouy-Chapman diffuse double layer theory, coupled with comparisons of this theory with closely related models for ion-pair chromatography. Insights into the retention mechanism reveal that an ion-exchange mechanism controls the retention of negatively charged solutes at applied potentials removed from the potential of zero charge (PZC). At potentials close to the PZC, the electrostatic model is less effective with the predominant retention mechanism likely involving hydrophobic interactions with the carbonaceous stationary phase. The combined effects of these findings are demonstrated by using a temporal gradient in supporting electrolyte concentration to optimize an EMLC separation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Chromatography A - Volume 1089, Issues 1–2, 30 September 2005, Pages 72-81
نویسندگان
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