Study On Analytical Technology Of Plant Growth Regulators In Fruits

Plant growth regulators are a class of synthetic pesticides that can effectively promote, inhibit, or modify growth and development of plants. Plant growth regulators are widely used in a range of the process of agricultural production, and the number and variety of plant growth regulators used is also increasing year by year. Most of the plant growth regulators are a class of chemical synthetic pesticides that may have certain harm more or less. The abuse and improper use of plant growth regulators resulted in more and more foods with excessive pesticide residue appeared on the market in recent years, the interests of consumers was seriously harmed. So, the study on analytical technology of plant growth regulators in fruits, has important practical significance to guarantee the safety of food. The determination of multiple plant growth regulators in Gannan navel orange by microwave–assisted extraction–liquid chromatography– triple quadrupole tandem mass(QqQ LC/MS) was systematically studied in this article, which has obtained satisfactory results. Generally speaking, major research results are as follows:1. A new and reliable method for the simultaneous determination of nine plant growth regulators, including daminozide, 6–benzylaminopurin, indole–3–aceticaci, indolepropionic acid, 3–indolebutyric acid, 4–iodophenoxyacetic acid, paclobutrazol, uniconazole and methyl naphthacetate in navel oranges was developed by QqQ LC/MS. Extraction was performed by acetone and ethyl acetate(V/V, 1:2) with microwave–assisted extraction technique. Cleanup of extracts was performed with dispersive–solid phase extraction(d–SPE) using active carbon as the sorbent. The identification of each analyte was established by chromatographic retention time, analyte–specific fragmentation patterns, and relative peak area ratios of precursor / production pairs. Under the optimized conditions, the average recoveries(six replicates), except for methyl naphthacetate, were in the range of 61.0–109.4% and limits of detection ranging from 0.01 to 162.2 ?g/kg. The proposed method meets the requirement of plant growth regulators residue analysis, and was successfully applied to the determination of plant growth regulators in navel orange samples.2. In this study, the unique carboxyl modified silica spheres were used as the support to grow ZIF–8 shell. The monodisperse SiO2@ZIF–8 core–shell microsphere was fabricated by solvothermal method and applicated in navel orange sample pretreatment. A rapid and efficient QqQ LC/MS method that simultaneously quantifies four plant growth regulators including 6–benzylaminopurin, indole–3–aceticaci, indolepropionic acid, 3–indolebutyric acid in navel oranges was established. A satisfactory result was obtained, the peak area of the four plant growth regulators against concentration was linear with good correlation coefficients of 0.99987–0.99991. Under optimized conditions, the limits of detection were from 3.0 to 59.4 ?g/kg for four plant growth regulators.3. To synthesize a novel and effective artificial paclobutrazol antigen, succinic anhydride method was used to modify the structure of paclobutrazol. Paclobutrazol hapten(PAC–HS) with the active group carboxyl group was obtained, and conjugated separately with BSA(bovine serum albumin) and OVA(ovalbumin) by carbodiimide method. Immunogen and coating antigen were obtained and designated as PAC–HS–BSA and PAC–HS–OVA, respectively. The paclobutrazol hapten was characterized by mass spectra, infrared scanning spectra and nuclear magnetic resonance hydrogen spectrogram. Ultraviolet spectrophotometry was applied to determine artificial paclobutrazol antigen. The coupling ratios of the conjugates were determined by matrix–assisted laser desorption/ionization time–of–flight mass spectrometry(MALDI–TOFMS). The results suggested that paclobutrazol antigen was successfully synthesized, which will greatly facilitate antibody production and immunoassay development.