کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1166193 1491090 2012 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Kinetic aspects of hollow fiber liquid-phase microextraction and electromembrane extraction
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Kinetic aspects of hollow fiber liquid-phase microextraction and electromembrane extraction
چکیده انگلیسی

In this paper, extraction kinetics was investigated experimentally and theoretically in hollow fiber liquid-phase microextraction (HF-LPME) and electromembrane extraction (EME) with the basic drugs droperidol, haloperidol, nortriptyline, clomipramine, and clemastine as model analytes. In HF-LPME, the analytes were extracted by passive diffusion from an alkaline sample, through a (organic) supported liquid membrane (SLM) and into an acidic acceptor solution. In EME, the analytes were extracted by electrokinetic migration from an acidic sample, through the SLM, and into an acidic acceptor solution by application of an electrical potential across the SLM. In both HF-LPME and EME, the sample (donor solution) was found to be rapidly depleted for analyte. In HF-LPME, the mass transfer across the SLM was slow, and this was found to be the rate limiting step of HF-LPME. This finding is in contrast to earlier discussions in the literature suggesting that mass transfer across the boundary layer at the donor–SLM interface is the rate limiting step of HF-LPME. In EME, mass transfer across the SLM was much more rapid due to electrokinetic migration. Nevertheless, mass transfer across the SLM was rate limiting even in EME. Theoretical models were developed to describe the kinetics in HF-LPME, in agreement with the experimental findings. In HF-LPME, the extraction efficiency was found to be maintained even if pH in the donor solution was lowered from 10 to 7–8, which was below the pKa-value for several of the analytes. Similarly, in EME, the extraction efficiency was found to be maintained even if pH in the donor solution increased from 4 to 11, which was above the pKa-value for several of the analytes. The two latter experiments suggested that both techniques may be used to effectively extract analytes from samples in a broader pH range as compared to the pH range recommended in the literature.

Figure optionsDownload as PowerPoint slideHighlights
► A comparison of the extraction kinetics of HF-LPME and EME was performed.
► In HF-LPME, the mass transfer across the membrane was the rate limiting step.
► In EME, mass transfer across the SLM was much more rapid due to electrokinetic migration.
► Different pH conditions in the sample were investigated for HF-LPME and EME.
► Both techniques may be used in an extended pH range as compared to earlier recommendations.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Analytica Chimica Acta - Volume 742, 12 September 2012, Pages 10–16
نویسندگان
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