MOLECULARLY IMPRINTED POLYMERS AS SELECTIVE MATERIAL FOR SEPARATION, PRECONCENTRATION, AND ANALYSIS OF ALPHA MANGOSTIN COMPOUNDS

• Main Author: Zakia S Si M Si, Neena
• Format: Dissertations
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/54984
• Institution: Institut Teknologi Bandung

Mangosteen (Garcinia mangostana L.) has been used in medicine due to its pharmacological compounds. The major secondary metabolite compounds in the mangosteen pericarp are xanthones which have bioactive properties. The greatest abundance of xanthon in fruit peels is the alpha mangostin compound, which is known to have antibacterial, anti-inflammatory, antioxidant, allergy, anti-tumor, and anti-cancer activities. Xanthones derivatives compounds in mangosteen pericarp have different benefits, thus a separation method is needed to obtain alpha mangostin compounds selectively. Sample preparation of the analytical process including isolation, clean-up, and concentrating of the analyte, for removal of potential interferents and the enrichment of the analyte are main objectives of sample pretreatment. Several methods have been developed for this separation, such as column fractionation, solvent extraction, and solid phase extraction (SPE). However, this method still has drawbacks such as not simple, requires a large volume of solvent, and is not selective for analyte target. The trends research that is developing to overcome that drawbacks is the use of selective sorbents of molecularly imprinted polymers as a functional materials for separation, clean-up, and preconcentration of analytes. The research of molecularly imprinted polymer (MIP) for alpha mangostin has never been reported. The aim of this research is to develop a selective functional material, that is a molecular imprinted polymer (MIP) which is selective for the isolation, clean-up and preconcentration processes for alpha mangostin compounds. The synthesized MIP is applied as a sorbent based on solid phase extraction, also known as molecularly imprinted solid phase extraction (MISPE). In this research, MIP for alpha mangostin have been synthesized using a precipitation techniques based on radical polymerization. Synthesis of MIP occurs from polymerization between alpha mangostin as a template, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and benzoyl peroxide (BPO) as an initiator, in acetonitrile porogen solvent, then the template molecule was removal to produce a selective cavity. As a control polymer, the polymer is synthesized without a template molecule called the non-imprinted polymer (NIP). Studies on the selection of functional monomers, crosslinking compounds, and comparisons of template: monomer: crosslinking have been carried out. The physical characterization of the synthesized material (MIP) was carried out including FTIR, SEM, TGA-DTG, and BET analysis. The performance of MIP was carried out with a batch system including pH optimization, adsorption kinetics, adsorption isotherm, and selectivity studies. Analyzes were performed using UV-Vis and HPLC spectrophotometry. MIP alpha mangostin was applied as a sorbent in the SPE column. The MISPE performance carried out includes the adsorption-desorption process, reusability, clean-up, preconcentration, and % recovery of real samples. The results of the study using batch system adsorption showed that the optimum adsorption conditions was pH 2, contact time of 180 minutes, maximum adsorption capacity (qm) was 16.19 for the MIP alpha mangostin sorbent and 4.22 for the NIP sorbent, with an imprinting factor (IF) value was 3.84. Adsorption kinetics followed pseudo-order 2 and Langmuir adsorption isotherm model. The separation factor and the adsorption selectivity of the alpha mangostin were carried out in the presence of xanthone with the selectivity coefficient (K) of 34.473 and the relative selectivity coefficient (K') of 5.365. Alpha mangostin MIP was successfully applied as a sorbent of SPE (MISPE) and has a good adsorption-desorption ability, gives 94.53% recovery using methanol: acetic acid 90:10 (% v/v) as eluent. MISPE reusability was obtained for up to 8 cycles of use, with adsorption percentage reaching above 90%, but desorption and recovery percentage began to decline to reach 75% on the 8th cycle. In the enrichment process, concentration was obtained with recovery of 101.67% when using 500 µL of eluent volume, with a concentration factor of 2 times. The functional material alpha mangostin MISPE was successfully applied to real samples that are herbal capsule products and crude extract of mangosteen peel. MISPE material is able to play a role in the removal of complex matrices from samples using water solvent in the washing step in SPE procedure. Alpha mangostin MISPE was successfully used for the application of clean-up and enrichment processes for alpha mangostin compounds in real samples with recovery percentage above 95% for herbal capsule samples and above 90% for crude extract samples of mangosteen pericarp. This research is expected to provide scientific contributions and information regarding the synthesis and performance of MIP for alpha mangostin compounds. The synthesized materials can be used as an alternative sorbents for selective and preconcentration separation techniques in the analysis of alpha mangostin compounds. Furthermore, alpha mangostin MIP can be used by industry for analysis purposes in the standardization process of herbal medicine containing alpha mangostin components.