The Determination Of Gibberellic Acid Residue In Vegetable And Fruit

Gibberellins are a big kind of phytohormone and they are of biterpene. At preset, people have separated and determined more than one hundred kinds of Gibberellins. Among them, gibberellic acid(GA3)is the most popular and important one. It is a kind of eurytopic growth hormone, regulating the plant' s upgrowth and development at its every step. Specially, it has obvious production-increacing effect on vegetables and fruits. As a kind of big-ring lactone antibiotic, it is prescribed thatthe maximum residue limitation of gibberellin is less than 0.2ppm in the USA andJapan. Usually in China we use the fluorescence technology for the analysis of thegibberellin residue. The pre-disposal of the sample is often adopted liquid-liquid extraction, the separation of thin-layer chromatography and the column chromatography. However the operation of these methods is cockamamie and needs a great amount of organic solvent. In this thesis the author set up the high-sensitivity and fast methods to detect the gibberellic acid residue in the vegetables and fruits by the purification of solid phase extraction. Also the methods has been given comparation between each other, which make out the basic reseach for the confirmation of the detecting standard of gibberellin residue.In the first place, a method of solid phase extraction followed by gas chromatography-mass spectrometry with selected ion mode for the direct determination of gibberellin residue in fruit samples has been developed. The retention behaviors of gibberellin samples on C18 small column were investigated. With the use of HP-1 capillary column and selected ion mode of MS, the disturbance from various origin can be overcomed. Its sensitivity is higher than full scan detection method, which makes the detection of gibberellin residue easier and faster.In the second place, with solid phase extraction, a method of high performanceliquid chromatography for the determination of gibberellin residue in tomato has been developed. The effection of different kinds of filling on gibberellin recovery in samples and their purified results are investigated. By comparison, we know that we can gain the satisfied refined sample solution with the purification of C18 small column. Under the optimized conditions, the purified effection of C18 small column is best, especially in the removement of the coloring matter, the soluble sugar and ester in the sample extraction. The linear range of this method is 0.20mg/L~l .05 X 102mg/L. Its detection limit is 0.011 mg/Kg, the average recoveries are 88.45%~ 95.90% and the RSD is from 1.15% to 6.56%.In the third place, by using the coupled technology of liquid-mass and the selection of the negative ion mode of electric spray ion, we have make a mass analysis about gibberellin and set up its residue quantified metod in tomato samples. Compared with the traditional liquid chromatography with UV detection, the LC-MS can remove the disturbance of the background impurity. It has higher selection and sensitivity and can predigest the extrction step of the sample. In the experiment we have optimized the ESI parameters. The detection limits of this method is 0.02ng/Kg, the average recoveries are 96.2%-104.6% and the RSD is from 4.63 % to 6.95 %. The method is very suited for the the determination of the trace substance in the complex multiple mixture, it is a good method for the detection of gibberellin residue in the plant.In the forth place, referring to the imports and exports commodinity trade testing standard of People's Republic of ChinaCSN 0350-95), based on the principle that, corporating with sulfuric acid, the alcohol solution of gibberellin will obtain a kind of fluorescence huang's matrix which can absorb rays and eradiate stronger radiation. With the purification of solid phase extraction, a fluorescence spectra analysis method for the determination of the gibberellin residues in the orange and strawberry has been developed by testing the fluorescence intensity of the fluorescence huang's matrix; In the experiment we optimize the ana...