Preparation of Molecularly Imprinted Fluorescent Probe for Rare Earth Complex and Determination of Malachite Green Residue

Malachite green is an artificially synthesized triphenylmethane compound. The disadvantages of conventional detection methods for malachite green, such as complicated pre-treatment, long time consuming and requiring the use of large instruments, result in the inability to detect promptly. So it is of great importance to invent a method that can detect malachite green residue effectively, rapidly and conveniently. Molecularly Imprinted Polymers (MIPs) are multiporous materials with specific recognition sites that allow the recognition and adsorption of specific target molecules. The rare earth complexes emit fluorescence at 618 nm, and the maximum absorption wavelength of malachite green is also 618 nm, and the combination of the two produces fluorescence quenching effect. Thereby a rare-earth complex based molecularly imprinted fluorescent probe was developed to detect malachite green in aquatic products. The specific content of malachite green in aquatic products was calculated by detecting the degree of its fluorescence quenching at 618 nm. A malachite green molecularly imprinted polymer was prepared by precipitation polymerization method using cryptic malachite green as a template, methacrylic acid as a functional monomer, ethylene dimethacrylate as a crosslinking agent, modified silica as a core, and the rare-earth fluorescent complex Eu(MAA)(3) phen as a fluorochrome, in the following conditions template monomer crosslinker = 1 : 4 : 10, Rare earth complexes = 15 mg, acetonitrile 60 mL, Molecular imprinting of rare-earth complexes, which have been successfully synthesized, was verified by carrying out TEM and FT-IR scanning analysis, and the fluorescence lifetime when examined was found to be 1 094. 11 mu s. However, the fluorescence lifetime after the addition of malachite green was 587. 49 mu s. The decrease of fluorescence lifetime illustrated that the quenching of MIPs by malachite green belonged to the fluorescence resonance energy transfer fret. After verifying the selectivity and adsorption properties of MIPs, malachite green was examined. The linear range of the optimized polymer for malachite green was 0 similar to 20 mu mol.L-1, the fluorescence quenching coefficient F-0/F shows a good linear relationship with the malachite green concentration, and the linear equation is F-0 = 1. 008c+ 0. 344(0. 1 similar to 1 mu mol.L-1, R-2 =0. 991), F-0/F= 0. 587c+0. 570(1 similar to 20 mu mol . L-1, R-2 = 0 . 999) with a detection limit of 0. 037 mu mol . L-1 (3 sigma/S, N = 9) , which was successfully applied as a fluorescent probe for the detection of malachite green in fish meat, with spiking recoveries in the range of 95. 61%similar to 102. 51%. These results indicate that the developed MIP based probes can detect malachite green residues easily, rapidly and accurately.