Study Of Analytical Methods Related To Chromatography For Plant Nutrition Elements And Phytohormones

A reversed-phase ion-pair high performance liquid chromatographic method,using tetrabutylammonium bromide(TBABr) as ion-pair reagent,has been developed for the simultaneous analysis of silicon(Si) and phosphorus(P) as heteropoly acids in soil and plant samples.The effect of the concentrations of ion-pair reagent,acetate buffer and organic modifier as well as the pH of buffer on separation was made clear. The reaction conditions and stability of heteropoly acids were investigated. Furthermore,the phenomenon occurred in the optimized process was also further researched.The separation was performed on a reversed-phase C₁₈ column within 11 min with 40:60(v/v) 0.1 M acetate buffer(pH 3.9)-acetonitrile(ACN) containing 0.8 mM TBABr as a mobile phase.The linear ranges of the peak area calibration curves for Si and P were 0.08-50 mg/L and 0.40-50 mg/L respectively.The detection limits calculated at S/N=3 were 0.0057 mg/L and 0.0280 mg/L for Si and P respectively. The method was successfully applied to the analysis of soluble and total contents of Si and P in soil and plant samples.A liquid chromatography-tandem mass spectrometry(LC-MS/MS) method was developed for simultaneous determination of three representative phytohormones in plant samples:indole-3-acetic acid(IAA),abscisic acid(ABA) and gibberellic acid (GA₃).A solid phase extraction(SPE) pretreatment method was used to concentrate and purify the three phytohormones of different groups in plant samples.The separation was carried out on a C₁₈ reversed-phase column,using methanol/water containing 0.2%formic acid(50:50,V/V) as the isocratic mobile phase at the flow-rate of 1.0 mL min^-1,and the three phytohormones were eluted within 7 min.A 2-dimensional linear ion trap mass spectrometer equipped with electrospray ionization source(ESI) was operated in negative ion mode.Selective reaction monitoring(SRM) was performed to quantify IAA,ABA and GA₃ at m/z transitions of 174→130; 263→153,219 and 345→239,301,respectively.Good linearities were found within the ranges of 5-200μg mL^-1 for IAA and 0.005-10μg mL^-1 for ABA and GA₃.Their detection limits based on a signal-to-noise ratio of three were 2.2μg mL^-1,0.003μg mL^-1 and 0.005μg mL^-1 for IAA,ABA and GA₃,respectively.Good recoveries from 95.5%to 102.4%for the three phytohormones were obtained.The results demonstrated that the SPE-LC-MS/MS method developed is highly effective for analyzing trace amounts of the three phytohormones in plant samples.