Determination of 5 Plant Hormones by Capillary Electrophoresis-Electrospray Ionization Mass Spectrometry

A method was proposed for the determination of five plant hormones, including indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), naphthalene acetic acid (NAA), 6-benzylaminopurine (BA) and abscisic acid (ABA), by capillary electrophoresis-electrospray ionization mass spectrometry (CE-ESI-MS). The optimized electrophoresis conditions for the separation and the electrospray ionization mass spectrometry conditions for the detection were as follows:15 mmol·L^-1 ammonium acetate-acetic acid buffer solution(pH 6.0) as electrophoresis running buffer solution, 2% (volume fraction) acetonitrile solution as organic modifier, the separation voltage of 22 kV, and 50%(volume fraction) isopropanol solution containing 0.11% (volume fraction) acetic acid as the sheath flow in mass spectrometry analysis.Under the optimal conditions, the above five plant hormones were separated at baseline within 16 min. Linear relationships between the corresponding peak area and mass concentration of the five plant hormones were found in definite ranges, with detection limits (3S/N) of 0.01-0.05 mg·L^-1. The RSDs of the peak area of the five plant hormones were less than 5.0% for 5 consecutive analysis of the same mixed standard solution. Test for recovery was made by the standard addition method, giving the results in the range of 92.4%-114%.