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Silicon nanowire arrays were patterned onto silicon chips by a combination of lithography and chemical vapor deposition using the vapor-liquid-solid growth method. Thus, highly reproducible sample deposition zones were obtained that were used for laser desorption ionization (LDI) mass spectrometric analysis of lipidic species with lithium salts as dopants. Using a conventional UV laser (337 nm), hydrocarbons and numerous lipids (triglycerides, diglycerides, wax esters) could be effectively lithiated yielding [M + Li]+ions. Upon doping with lithium hydroxide the SiNW arrays yielded high signal-to-noise ratios with low limits of detection (e.g.750 pg tripalmitin on target with S/N 5) and efficient ionization for a range of fatty acids (FA), mono-, di- and triglycerides and hydrocarbons (HC), in the form of [FA − H + 2Li]+, [mono- or diglyceride − H2O + Li]+, or [triglyceride + Li]+and [HC + Li]+, respectively. It is expected that these chips will find a broad range of applications in the analysis of natural compounds and food control. [ABSTRACT FROM AUTHOR]

Insect cuticular hydrocarbons (CHCs) were probed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry with a lithium 2,5-dihydroxybenzoate matrix. CHC profiles were obtained for 12 species of diverse insect taxa (termites, ants, a cockroach, and a flesh fly). MALDI spectra revealed the presence of high molecular weight CHCs on the insect cuticle. Hydrocarbons with more than 70 carbon atoms, both saturated and unsaturated, were detected. When compared with gas chromatography/mass spectrometry (GC/MS), MALDI-TOF covered a wider range of CHCs and enabled CHCs of considerably higher molecular weight to be detected. Good congruity between GC/MS and MALDI-TOF was observed in the overlapping region of molecular weights. Moreover, a number of previously undiscovered hydrocarbons were detected in the high mass range beyond the analytical capabilities of current GC/MS instruments. MALDI was shown to hold potential to become an alternative analytical method for insect CHC analyses. The ability of MALDI to discriminate among species varying in the degree of their relatedness was found to be similar to GC/MS. However, neither MALDI-MS nor GC/MS data were able to describe the phylogenetic relationships. [ABSTRACT FROM AUTHOR]

Summary. The biosynthetic pathway of the formation of males'marking pheromones of two bumblebee species, Bombus lucorum and B.lapidarius, was studied for the first time. After applications ofdeuterium labelled palmitic acid ([2H31]-hexadecanoic acid) into eitherthe head capsules or abdomens the corresponding deuterium labelledpheromone components were detected in the labial gland (LG) extracts ofmales of both species. In B. lucorum, ethyl [2H29]-hexadec-9-enoate andethyl [2H31]-hexadecanoate were identified. No deuterium-labelled ethyltetradecenoate, that would correspond to shortening of the carbon chain,was detected. In B. B. lapidarius, [2H31]-hexadecan-1-ol and[2H29]-hexadec-9-en-1-ol were found in the LG. Furthermore, thedeuterium labelled precursor was incorporated into triacylglycerols(TAG) of the fat bodies of males. In vitro incubation of the labialglands of B. lucorum males with deuterium-and 13C-labelled palmiticacid lead to the formation of saturated ethyl esters only. [ABSTRACT FROM AUTHOR]