Abstract: Ultrasonic extraction combined with liquid chromatography was used to accurately determine eight plant growth regulators [6-benzylaminopurine, indole acetic acid, abscisic acid, indole butyric acid, naphthalene acetic acid, clopidogrel, uniconazole, 2,4-dichlorophenoxyacetic acid （2,4-D）] in fertilizer. The fertilizer samples were extracted with methanol solution containing 0.1% formic acid, separated on ZORBAX SB-C₁₈ column, and gradient eluted with methanol and 0.1% formic acid water as the mobile phase. The determination was carried out at 280 nm and quantified by the external standard method. The results showed that the mass concentration of eight plant growth regulators had a good linear relationship with the corresponding peak area in their respective linear ranges, and the correlation coefficients were greater than 0.999 8. The detection limits were 0.5~10.0 mg/kg. The blank fertilizer sample was used for the standard addition recovery test. The recovery rates were 78.2%~109.4%, and the relative standard deviations were 1.06%~5.91%. This method is accurate, fast and efficient, which is suitable for the simultaneous determination of eight plant growth regulators in fertilizers.

Key words: fertilizers, plant growth regulators, liquid chromatography