Study And Applications Of New Analytical Technology For The Simultaneous Determination Of Plant Growth Regulators Residues In Food

Plant growth regulators, which play important roles in regulating the growth, metabolism and development of plants, are synthesized and widely used in agriculture. The abuse and improper use of plant growth regulators resulted in a high risk contamination in food and food safety accidents have occurred frequently. Plant growth regulator residues in food have become one of the main factors of influencing China’s food safety. Therefore it is necessary to monitor their residues in agricultural products. In recent years, the detection of auxins is a hot topic in the field of biochemistry, primarily with the purpose of researching the concentrations of endogenous auxins effect on plant growth, fruit ripened and other aspects, while the research on auxins residues in food has been reported relatively less. In this article, we systematically studied the determination methods of plant growth regulators residues in fruits and vegetables with satisfactory results. The main results of the study are as follows:1. A new method for the determination of plant growth regulators, including2-Naphthoxyacetic acid,2,4-Dicholrophenoxyacetic acid and1-naphthlcetic acid in radish was developed by liquid chromatography/electrospray ionization mass spectrometry. The mass spectrometric quantitative analysis based on selective ionic measurement by electro-spray ionization in negative mode. In this study, the application of ultrasound-assisted extraction technique for the determination of plant growth regulators was developed, and the experimental variables were optimized through orthogonal array experimental design. Good linearity was found in the range of0.01-10μg/mL for the above Plant growth regulators which were eluted with8min. The detection limit based on a signal-to-noise ratio of three were3.2ng/mL for2-Naphthoxyacetic acid,7.3ng/mL for2,4-Dicholrophenoxyacetic acid and4.9ng/mL for1-naphthlcetic acid. Under optimized conditions, the average recoveries of77.6%-105.1%were obtained by adding0.01mg/kg、0.05mg/kg and0.50mg/kg standards, and the relative standard deviations were3.5%-15.9%. The result of this method used in the determination of plant growth regulators in radish was satisfactory.2. A new method for the determination of six plant growth regulators, including3-indolylacetic acid,3-indolepropionic acid,2-naphthoxyacetic acid,2,4-dicholrophenoxyacetic acid,1-naphthlcetic acid and methyl naphthalene-1-acetate in pears was established by liquid chromatography/electrospray ionization mass spectrometry. In this study, the application of MAE technique for the determination of plant growth regulators in fruit was firstly developed, and the experimental variables were optimized through orthogonal array experimental design. In addition, three clean-up techniques were respectively investigated for purification of the pear samples. And the comparison reveals that liquid-liquid purification method could eliminate the interfering agents in sample matrix effectively and the method was simple and cost-effective. Good linearity was found in the range of0.01-10μg/mL for the above plant growth regulators which were eluted within17min. The detection limit based on a signal-to-noise ratio of three ranged from1.31ng/mL to9.48ng/mL. Under optimized conditions, the average recoveries of78.89%-118.0%were obtained by adding0.01mg kg-1,0.05mg kg-1and0.5mg kg-1standards, and the relative standard deviations were1.4%-10.3%. A satisfactory result was obtained in the determination of plant growth regulators in pears.3. A sensitive, selective and environmental friendly method for the determination of3-indolepropionic acid,3-indolebutyric acid,1-naphthlcetic acid and2-naphthoxyacetic acid in radish by ion exchange chrom atography (IEC) with fluorescence detec tion. In this study, the application of MAE technique for the determination of plant growth regulators was developed, and the experimental variables were optimized through orthogonal array experimental design. Under the op timized conditions, the detection limit based on a signal-to-noise ratio of three for4plant growth regulators ranged from0.029ng/mL to0.722ng/mL, the average recoveries of NAA, IPA, IBA and BNOA were91.4%-98.9%,96.2.%-106.0%,85.6%-92.4%and98.3%-102.7%, respectively, with spiked at0.01mg/kg、0.05mg/kg and0.50mg/kg, and the relative standard deviations werel.2%-3.5%. The proposed method meets the requirement of plant growth regulators residue analysis, and was successfully applied to the determination of plant growth regulators in radish.