title: Preparation of guanidinium terminus-molecularly imprinted polymers for selective recognition and solid-phase extraction (SPE) of [arginine]-microcystins.
abstract: About 70 % of microcystin (MC) congeners reported in literature consist of L-arginine amino acid (R) with its guanidinium terminal extending out of the cyclic moiety of these MCs. Molecularly imprinted polymer (MIP) bearing guanidinium terminus cavities was successfully synthesised using L-arginine as a template. Non-imprinted polymer (NIP; without template) was also synthesised for control purposes. The surface area, total pore volume and average pore diameter of MIP and NIP were 267.13 m(2)/g, 0.63 cm(3)/g and 88.39 Å; 249.39 m(2)/g; 0.54 cm(3)/g and 87.14 Å, respectively. The polymers were investigated for selective recognition and extraction of [arginine]-MCs in water using solid-phase extraction/liquid chromatography-electrospray ionisation-mass spectrometry (SPE/LC-ESI-MS) method. Representative model standard solutions (0.5-10.0 μg/L) of MC-LR and MC-LY were spiked in distilled water, recovered by SPE and quantified by LC-ESI-MS. In this study, Oasis Waters™ HLB cartridges served as positive control SPE sorbents. The MIP recognised MC-LR with high recoveries (70.8-91.4 %; r(2) = 0.9962) comparable to HLB cartridges (71.0-91.85 %; r(2) = 0.9993), whereas the NIP did not recognise or retain MC-LR. Also, neither MIP nor NIP recognised or retained MC-LY. Extracts of environmental toxic Microcystis aeruginosa were subjected to SPE procedure employing MIP, NIP and HLB cartridges. Microcystin-LR, -YR, -RR, -WR, -(H4)YR and (D-Asp(3), Dha(7))MC-RR were extracted by MIP and HLB cartridges only as confirmed by LC-ESI-MS. This study demonstrated that the prepared MIP have potential applications for the removal in water and LC-ESI-MS identifications of MCs consisting the guanidinium moiety, i.e.[arginine]-MCs, and in particular targeting commonly encountered toxic congeners, MC-LR, -YR and -RR.
authors: Department of Applied Chemistry, Faculty of Science, University of Johannesburg, Johannesburg, South Africa.
authors: Elbert A
authors: EA
authors: Mbukwa
authors: Titus A M
authors: TA
authors: Msagati
authors: Bhekie B
authors: BB
authors: Mamba
mesh_terms: D001120:Arginine / Q000302:isolation & purification; D002853:Chromatography, Liquid; D019791:Guanidine / Q000737:chemistry; D052998:Microcystins / Q000302:isolation & purification*; D046931:Microcystis / Q000302:isolation & purification*; D054802:Molecular Imprinting / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization; D014871:Water Microbiology
chemical_list: D052998:Microcystins; D011108:Polymers; D001120:Arginine; D019791:Guanidine