Identification of an unknown b-agonist in feed by liquid chromatography/bioassay/quadrupole time-of-flight tandem mass spectrometry with accurate mass measurement.

A new approach to the search for residues of unknown growth promoting agents such as anabolic steroids and -agonists in feed is presented. Following primary extraction and clean-up, samples are separated using gradient liquid chromatography (LC). The effluent is split towards two identical 96-well fraction collectors and an optional electrospray quadrupole time-of-flight mass spectrometry (QTOFMS) system for accurate mass measurement. One 96-well plate is used for a bioassay (enzyme-immuno assay, receptor assay) and will detect the bioactivity and position of the relevant peak in the chromatogram. The positive well in the second 96-well plate is used for identification by LC/QTOFMS/MS. The value of this LC/bioassay/QTOFMS/MS methodology is highlighted by the finding and structure elucidation of a new -agonist in a feed extract.

Comparison of mass transfer effects in the heterogeneously catalysed hydrogenation of phenyl acetylene in heptane and an ionic liquid

The selective heterogeneous catalytic reduction of phenyl acetylene to styrene over palladium supported on calcium carbonate is reported in both an ionic liquid and a molecular solvent. By using a rotating disc reactor in conjunction with results from a stirred tank reactor it is possible, for the first time, to disentangle the mass transfer contributions in the ionic liquid system. For both heptane and 1-butyl-3-methyl imidazolium bis{(trifluoromethyl)sulfonyl}imide, the reaction in the rotating disc reactor is dominated by reaction in the entrained film on the disc compared with very limited reaction in the bulk liquid. The lower reaction rate obtained in the ionic liquid compared with the organic solvent is shown to be due to the slow transport of the hydrogen dissolved in the liquid. It is clear from the results presented herein that, although the hydrodynamics of similar reactors used for biological treatment of wastewater are well understood, on using a more viscous fluid and higher rotation speeds necessary for fine chemical catalysis these simple relationships breakdown.

The VLT-FLAMES survey of massive stars: mass loss and rotation of early-type stars in the SMC

We have studied the optical spectra of a sample of 31 O- and early B-type stars in the Small Magellanic Cloud, 21 of which are associated with the young massive cluster NGC 346. Stellar parameters are determined using an automated fitting method (Mokiem et al. 2005, A&A, 441, 711), which combines the stellar atmosphere code FASTWIND (Puls et al. 2005, A&A, 435, 669) with the genetic algorithm based optimisation routine PIKAIA (Charbonneau 1995, ApJS, 101, 309). Comparison with predictions of stellar evolution that account for stellar rotation does not result in a unique age, though most stars are best represented by an age of 1-3 Myr. The automated method allows for a detailed determination of the projected rotational velocities. The present day v(r) sin i distribution of the 21 dwarf stars in our sample is consistent with an underlying rotational velocity (v(r)) distribution that can be characterised by a mean velocity of about 160-190 km s(-1) and an effective half width of 100-150 km s(-1). The vr distribution must include a small percentage of slowly rotating stars. If predictions of the time evolution of the equatorial velocity for massive stars within the environment of the SMC are correct (Maeder & Meynet 2001, A&A, 373, 555), the young age of the cluster implies that this underlying distribution is representative for the initial rotational velocity distribution. The location in the Hertzsprung-Russell diagram of the stars showing helium enrichment is in qualitative agreement with evolutionary tracks accounting for rotation, but not for those ignoring vr. The mass loss rates of the SMC objects having luminosities of log L-star/L-circle dot greater than or similar to 5.4 are in excellent agreement with predictions by Vink et al. (2001, A&A, 369, 574). However, for lower luminosity stars the winds are too weak to determine. M accurately from the optical spectrum. Three targets were classified as Vz stars, two of which are located close to the theoretical zero-age main sequence. Three lower luminosity targets that were not classified as Vz stars are also found to lie near the ZAMS. We argue that this is related to a temperature effect inhibiting cooler from displaying the spectral features required for the Vz luminosity class.