Analysis and quantitation of insect juvenile hormones using chemical ionization ion-trap mass spectrometry

A method for identification and quantitation of insect juvenile hormones (J H) has been developed using capillary gas chromatography-chemical ionizatio n (isobutane)-ion-trap mass spectroscopy. The method does not require deriv atization of samples or use of selected ion monitoring. Analysis over a mas s range of 60-350 u allowed for identification of as little as 0.01 pmol of individual JH homologs. Quantitative analysis was based on the ion intensi ties of six diagnostic ions and the summed intensities of these ions for ea ch homolog, The ratio of diagnostic ions did not vary significantly over a range of concentrations from 2.7 to 200 pg. The technique was used to ident ify and quantify the amounts of JH homologs secreted by individual retrocer ebral complexes from the moth Manduca sexta maintained in tissue culture an d to identify JH III from hexane extracts of hemolymph of the Caribbean fru it fly. No discrimination due to disparate abundance ratios of the individu al homologs was found when analyzing natural product samples differing in c oncentration by at least fivefold. The technique allows for facile, concret e identification and quantitation of biologically relevant amounts of JH. T he ability to analyze samples without derivatization or fractionation by ch romatographic methods, coupled with data acquisition over a broad mass rang e, provides levels of accuracy and confidence greater than those of other m ethods. (C) 2000 Academic Press.