MOLECULARLY IMPRINTED POLYMERS AS SELECTIVE FUNCTIONAL MATERIAL FOR SEPARATION-PRECONCENTRATION AND ANALYSIS OF CURCUMINOIDS

• Main Author: Wulandari, Meyliana
• Format: Dissertations
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/32819
• Institution: Institut Teknologi Bandung

Curcumin powder contains of curcuminoids. These curcuminoids include of 77% CUR (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), 17% DMC (demethoxycurcumin), and 3% BDMC (bisdemethoxycurcumin). Each of curcuminoids may have different chemical properties. For all these reasons and also in order to avoid side effects that may occur at the ineffective dose of these new drug candidates, the development of separation methods for efficient isolation and quantification of curcuminoids would be essential prior to their use in pharmaceutical preparations. Since its introduction in the early 1980s, molecular imprinting polymers has demonstrated as the potential technique for the separation of analytes with a high degree of selectivity. The polymers are obtained by polymerization of functional monomers and cross-linkers in the presence of the target analyte (or a molecular analogue). The target molecule acts as a template during the polymerization step, in a manner that, after its removal (normally templates are interacting with functional monomers only via non-covalent, reversible interactions) a solid with empty cavities or pockets that are complementary on size, shape and functional groups to the target analyte, is obtained. Rebinding of the target may then take place via non-covalent bonding. Because of the relatively low cost and ease of preparation, stability at high temperature and pressure, and chemical resistance to harsh environments, imprinted polymers have found use in a wide variety of applications. The MIPs for separation and analysis of curcuminoids have not much been published. Therefore, in this paper, the synthesis of MIPs employing either HPB (MIPs-1) or a reduced form of BDMC (MIPs-2) as the template molecules will be presented. HPB and reduced BDMC have been chosen instead of the target analytes themselves, because they lack of the vinyl groups that could participate in the polymerization process, inducing the covalent attachment of the template molecule to the polymer matrix. N-(2-aminoethyl) methacrylamide hydrochloride was chosen as the functional monomer because it enables hydrogen bonding with the template. Selected crosslinker, radical initiator, and porogen were ethylene glycol dimethacrytlate/EGDMA, 2,2'-azobis (2'4-dimethyl valeronitril)/ABDV and acetonitrile, respectively. The interaction of one of the target analytes, CUR, with the functional monomer has been characterized by UV-Vis spectrophotommetry titrations in acetonitrile for prediction of template to monomer moles ratio. The result showed that the ratio between template and monomer is 1:2. Rebinding experiments with two target curcuminoids (Cur and BDMC) allowed determining the binding performance of both, MIPs-1 and MIPs-2. Also the imprinting factors for these two target analytes were determined by HPLC studies employing different mixtures of H2O:MeCN as eluents. Batch retention capacity of curcumin was bigger than its column retention capacity. Batch retention capacity was smaller than its column retention capacity. The different polymers (MIPs-1, MIPs-2 and NIP) have been characterized by using the Freundlich isotherm model. A 0.5 mg L-1 of curcumin and BDMC were flowed separately to the SPE cartridges and the breakthrough volumes were reached at 41 mL and 34 mL for curcumin and BDMC, respectively. Then MIPs were applied to the SPE sorbent (MISPE). The studied parameters included optimation of loading solvent and eluent. The selected loading solvent was water and methanol was selected as the eluent. The recovery % was up to 75% for elution with 1 mL of methanol. The selectivity was studied by HPLC using C-18 as column and water: methanol: acetonitrile (50: 5: 45, % v.v) as mobile phase. Good separation with high resolution was generated. If methanol: water (100: 0, 90: 10, % v/v) were used as eluent for SPE, both curcumin and BDMC were retention. When the methanol composition was decreased, small amount of analyte was eluted then the elution process took long time. Methanol: water ((75: 25, % v/v) pH 9 was used to elute BDMC and then curcumin was eluted with pure methanol. Analytical performance of the develop method was described as liniearity, repeatability, detection limit, and accuracy of curcumin analysis are 0.9899; 3.59; 0.12 mg L-1, 105.8%, respectively. Whereas for BDMC was 0.9831; 4.4; 0.19; 104.7%. Flow Injection analysis performance including enrichment factor, concentration efficiency, and consumptive index for curcumin and BDMC were 10 and 6, 0.4/minutes, 10.4 mL, respectively. Enrichment factor for MISPE-HPLC-UV-Vis for curcumin and BDMC were 4 and 2, while for MISPE-HPLC-fluorescence method was described 2 for curcumin and 3 for BDMC. Sample analysis of herbal extract was calculated as 0.02% w/w and BDMC 0.01% w/w. As described above, the develop menthod of MISPE-FIA-UV-Vis could be used for separation, preconcentration, analysis of curcuminoids from herbal extract samples.