Comparison of Extraction Methods for the Quantification of Phytohormones From Tomato Fruits and Leaves by LC–MS/MS

ABSTRACT Purification of crude plant extracts by solid‐phase extraction (SPE) is assumed to reduce matrix effect in phytohormone quantification by LC–MS/MS, but its efficacy is rarely assessed. We used postextraction spiking of isotope‐labeled phytohormones to estimate matrix effect, recovery, and processes efficiency in extracts prepared according to protocols that implement SPE with tC18 and HLB sorbents, respectively, and according to a protocol that does not include SPE. Across six structurally diverse phytohormone classes and tomato fruit and leaf matrices, we did not find significant matrix effects associated with extracts prepared with no SPE. For recovery efficiency, process efficiency, and variation, we rarely found conclusive evidence that the methods that implemented SPE were optimal relative to the one that does not. A notable exception was fruit extracts prepared using HLB sorbents, which had minimal variation for indole‐3‐acetic acid, trans ‐zeatin, and trans ‐zeatin riboside, all of which were detected with positive electrospray ionization.