Liquid chromatography-electrospray ionization-mass spectrometric quantitation of juvenile hormone III in whole body extracts of the Formosan subterranean termite

Masao Miyazaki, Louisiana State University
Lixin Mao, LSU Agricultural Center
Gregg Henderson, LSU Agricultural Center
Roger A. Laine, Louisiana State University

Abstract

Juvenile hormone (JH) III is responsible for control of a variety of insect physiological and developmental states, including caste differentiation of the Formosan subterranean termite (Coptotermes formosanus Shiraki). We report here a simplified, efficient sample preparation and an optimized LC-ESI-MS method for quantifying JH III in whole body extracts. Sample preparation comprises hexane extraction (from termite whole bodies) and C18 cartridge purification. Previous LC-ESI-MS protocols exhibited the following two problems: (1) ion fragmentation differed when comparing spectra from insect samples and authentic JH III and (2) a JH III monitoring ion was not resolved from other unknown compounds in whole body samples from termites. To overcome these problems, we used a pentafluorophenyl LC column and water/acetonitrile containing ammonium acetate as solvent. In a mass chromatogram (m/z 235) of termite samples, a peak was detected at the retention time of authentic JH III, and MS2 of this peak confirmed that the ion is a fragment of JH III, [M-CH3OH+H]+, being the base peak in both termites and authentic JH III samples. The protocol enables quantification of JH III in a single termite with signal/noise >10:1 and the limit of quantification is 21 pg. © 2009 Elsevier B.V. All rights reserved.