Synthesis Of Molecularly Imprinted Polymers For Solid-Phase Extraction Of Ellagic Acid From Pomegranate Fruit Peel
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Date
2017-02
Authors
Al-Attabi, Ali Jalil Mjali
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
This study was performed to evaluate the application of MIPs as a sorbent material in solid phase extraction (SPE) for the extraction of ellagic acid from pomegranate fruit peel. Ellagic acid-imprinted polymers were successfully prepared via a non-covalent approach, which involved self-assembly between ellagic acid and acrylamide as a template molecule and functional monomer, respectively. The highly three dimensional crosslinked polymer was obtained after reaction of pre-polymerisation complex with divinylbenzene (DVB), and azobisisobutyronitrile (AIBN) was used as the initiator. The porogen used was a mixture of N-methyl-2-pyrrolidone and acetonitrile with a ratio of 15:85 (v/v %). Free radical polymerisation method was used in precipitation polymerisation at 60 °C for 24 hours. The molar ratio of functional monomer to crosslinker was constant at 1:5, while the molar ratios of template molecule to functional monomer were 1:5, 1:6 and 1:7. The polymers labelled as MIP 1, MIP 2, MIP 3 and NIP were separately packed in an analytical column. Acetone was used as slurry and packing solvent. The output was obtained as microspheres and was used as HPLC stationary phase. Soxhlet extraction was conducted to remove the ellagic acid and the recognition sites were obtained. All polymers prepared were characterised using Fourier transform infrared (FTIR), nitrogen sorption porosimetry and scanning electron microscopy (SEM). Chromatographic evaluations were carried out on these columns to find the best molar ratio of ellagic acid to acrylamide. MIP 1 proved to be the best column
material with the imprinting factor (IF) of 3.60. MIP 1 also gives the best selectivity for ellagic acid. Hence MIP 1 was used to study its potential as a sorbent for solid phase extraction (SPE) in this thesis. A number of solvents were studied to evaluate as the suitable solvents for loading, washing and elution of SPE. It was found that N-methyl-2-pyrrolidone/acetonitrile (10:90 % v/v) gave the best loading solvent, 3 mL of DCM/MeCN (5:95 v/v) as the best washing solvent and 10% acetic acid in methanol as the best elution solvent. Pomegranate peel powder extract was used as a source of ellagic acid. The acidic methanol solution was used to extract the sample. MIP 1 was used to extract ellagic acid from the mixtures. The recoveries of ellagic acid from pomegranate peel extraction spiked at 2.2, 4.4 and 11 mg g-1 ranged from 97.5-99.1 %. The proposed method was applied to ten samples of pomegranate peel obtained from local markets. The ellagic acid ranged from 25.53-36.33 mg g-1 was found in the pomegranate samples.
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Keywords
Extraction of ellagic acid , from pomegranate fruit peel