کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9748564 | 1493785 | 2005 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The adsorption mechanism of nortryptiline on C18-bonded Discovery
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کلمات کلیدی
Acetonitrile - استونیتریلExcess isotherm - ایزوترم بیش از حدFrontal analysis - تجزیه و تحلیل جلوAdsorption equilibrium - تعادل جذبAffinity energy distribution - توزیع انرژی وابستهSilica - سیلیس یا سیلیکاRetention mechanism - مکانیزم نگهداریColumn heterogeneity - ناهمگنی ستونNortriptyline - نورتریپتیلینPeak tailing - نیشخند
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: The adsorption mechanism of nortryptiline on C18-bonded Discovery The adsorption mechanism of nortryptiline on C18-bonded Discovery](/preview/png/9748564.png)
چکیده انگلیسی
The adsorption isotherms of an ionizable compound, nortriptyline, were accurately measured by frontal analysis (FA) on a C18-Discovery column, first without buffer (in an aqueous solution of acetonitrile at 15%, v/v of ACN), then with a buffer (in 28%, v/v ACN solution). The buffers were aqueous solutions containing 20âmM of formic acid or a phosphate buffer at pH 2.70. The linear range of the isotherm could not be reached with the non-buffered mobile phase using a dynamic range larger than 40â000 (from 1.2à 10â3âg/L to 50âg/L). With a 20âmM buffer in the liquid phase, the isotherm is linear for concentrations of nortriptyline inferior to 10â3âg/L (or 3âμ mol/L). The adsorption energy distribution (AED) was calculated to determine the heterogeneity of the adsorption process. AED and FA were consistent and lead to a trimodal distribution. A tri-Moreau and a tri-Langmuir isotherm models accounted the best for the adsorption of nortriptyline without and with buffer, respectively. The nature of the buffer affects significantly the middle-energy sites while the properties of the lowest and highest of the three types of energy sites are almost unchanged. The desorption profiles of nortriptyline show some anomalies in relation with the formation of a complex multilayer adsorbed phase of acetonitrile whose excess isotherm was measured by the minor disturbance method. The C18-Discovery column has about the same total saturation capacity, around 200âg of nortriptyline per liter of adsorbent (or 116âmg/g), with or without buffer. About 98-99% of the available surface consists in low energy sites. The coexistence of these different types of sites on the surface solves the McCalley's enigma, that the column efficiency begins to drop rapidly when the analyte concentration reaches values that are almost one hundred times lower than those that could be predicted from the isotherm data acquired under the same experimental conditions. Due to the presence of some relatively rare high energy sites, the largest part of the saturation capacity is not practically useful.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Chromatography A - Volume 1095, Issues 1â2, 18 November 2005, Pages 27-39
Journal: Journal of Chromatography A - Volume 1095, Issues 1â2, 18 November 2005, Pages 27-39
نویسندگان
Fabrice Gritti, Georges Guiochon,