Determination of traces of fipronil and its metabolites in pollen by liquid chromatography with electrospray ionization-tandem mass spectrometry

Fipronil is a pesticide suspected of having harmful effects on honey bees at microgram per kilogram levels. Considering the lack of methodology, it thus appeared to be necessary to develop a method for the determination of the lowest amounts of fipronil and its metabolites in pollen. This paper describes a new analytical method with a limit of quantification (LOQ) of 0.1 microg/kg for a representative sample weight of 5 g. In the case of a field study, this tool was used for checking the possible existence of fipronil and/or metabolites in pollen samples, but none of them contained residues higher than the LOQ. This three-step rapid method uses liquid-solid solvent extraction with mechanical grinding, followed by liquid-liquid partitioning and Florisil solid-phase extraction for the two cleanup steps. The quantification is made by liquid chromatography with electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Indeed, combined with an adequate sample treatment, this technique offers good sensitivity and selectivity in such a complex matrix. The method has given good recoveries of 74-104% with relative standard deviations of 5.6-18.2%.     

Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.