Modified Vortex-Assisted Microextraction Methods For The Determination Of Sugar Degradants
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Date
2017-08
Authors
Abu Bakar, Nur Bahiyah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
This thesis deals with the modification of new methods based on vortex-assisted liquid-liquid microextraction (VALLME). The aims of the methods are to modify the technique to be suitable for the extraction of polar/ or charged compounds, enhanced the extraction efficiency and phase separation. A salting out-VALLME was developed for the determination of furfurals (2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF), 5-hydroxymethylfurfural (5-HMF)) and patulin in fruit juices. The extraction of these polar compounds was achieved with the aid of salt addition and suitable organic solvent. The separation was performed using high performance liquid chromatography coupled with diode array detector (HPLC–DAD) and ODS Hypersil C18 column under gradient elution. Good linearities (r2 > 0.99) and low limits of detection (LODs) (0.28–3.2 μg L⁻1) were obtained. The validated salting out-VALLME–HPLC method was applied for the analysis of furfurals and patulin in fruit juices. Vortex- and carbon dioxide (CO2)-assisted liquid–liquid microextraction with salt addition for the isolation of furanics (5-HMF, 5-MF, 2-F, 3-F, 2-furoic and 3-furoic acids) was proposed. Purging with CO2 was applied after vortexing step to enhance the phase separation and mass transfer of the analytes. Moreover, the selection of semi-polar solvent was increase the extraction efficiency. The analytes were baseline separated using HPLC–DAD with ODS Hypersil C18 column under gradient flow rate. The proposed method showed good linearities (r2 > 0.999), LODs (0.08–1.9 μg L⁻1) and recoveries (80.7–122 %). The validated method was successfully applied for the determination of the furanics in concentrated juices and dried fruits. A simple capillary zone electrophoresis (CZE) method for the separation of sugar degradants (α-dicarbonyl (glyoxal, methylglyoxal) and furfural (2-F, 5-MF, 5-HMF) has been developed for the first time. As these compounds are neutral and weak chromophore, a derivatization using Girard’s T reagent was studied. All analytes were baseline separated in less than 20 min. A new microextraction method based on ion-pair vortex-assisted liquid–liquid–liquid microextraction (IP–VALLLME) followed by CZE was developed for the determination of sugar degradants in human urine after derivatization step. The selection of IP reagent to assist the mass transfer of the ionizable compounds and to ensure high extraction efficiency, constitutes the major objective of the present studies. The proposed method showed lower LODs (0.155–20.7 μg L⁻1) and good enrichment factors (11–493 folds). The validated method was successfully applied for the determination of the studied compounds in urine after consumption of dried apricot.
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Keywords
Modified vortex-assisted microextraction methods , for the determination of sugar degradants