Green Approaches Involving Liquid Phase Microextraction, Monolithic Column And Capacitively Coupled Contactless Conductivity Detection In Flow Techniques
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Date
2011
Authors
Makahleh, Ahmad (Moh'd Ali) Hasan
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Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
This thesis deals with the developments of new analytical methods in flow techniques (high performance liquid chromatography (HPLC) and flow injection analysis). An important goal of these methods is the use of green approaches (solventless microextraction, monolithic column, capacitively coupled contactless conductivity detector (C4D), and automation) to achieve the respective objectives.
A hollow fiber liquid phase microextraction technique was used as sample preparation for the extraction of trace amounts of rosiglitazone (anti-diabetic drug) in biological fluids. The microextraction method, in tandem with HPLC, was successfully optimized and validated. The optimum conditions were: extraction solvent, dihexyl ether; donor phase pH, 9.5; acceptor phase, 0.1M HCl; stirring speed, 600 rpm; extraction time, 30 min and without addition of salt. Enrichment factor of 280 was achieved.
Betulin and betulinic acid in natural product extracts were successfully separated using a monolithic column. The HPLC method was optimized using plate model where the optimum efficiency of the column was selected. Under the optimized conditions (mobile phase 95:5 % (v/v: acetonitrile:water); flow rate, 1.0 mL min-1; ambient temperature) the two compounds were separated in less than 5 min. Good linearities were obtained for both analytes over the concentration range 1 - 200 mg
L-1 with correlation coefficients > 0.999. The method was used to analyze betulin and betulinic acids in plant extracts. The proposed method was clearly superior over the other reported methods using conventional C18 columns.
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Keywords
Green approaches involving liquid phase microextraction , contactless conductivity detection in flow techniques