Sinapine source

MALDI mass spectra were acquired on a Broker Reflex mass spectrometer equipped with a 337 nm nitrogen laser and a multiple sample stage source. The spectra were acquired in linear mode, represent the sum of 20 laser shots, and are un-smoothed. All ions were desorbed at a laser power just above threshold, at an ion extraction voltage of 30 kV. The matrix used was a saturated solution of 3,5-dimethoxy-4-hydroxycinnamic acid (sinapinic acid, Aldrich Chemicals) in a 1 1 water/acetonitrile solution. Low-mass matrix ions were deflected by the application of a voltage pulse. 

Matrix-assisted laser desorption ionisation (MALDI) can analyse molecules with large mass >10 000 Da. The technique is similar to FAB and is also considered a soft ionisation process. The analyte is mixed with a matrix such as sinapinic acid or 2,5-dihydroxybenzoic acid that strongly absorbs UV radiation. A few microlitres of this analyte/matrix mixture is deposited on the sample plate and dried. The plate is inserted into the source region... 

The conversion of commercial rape (see rapeseed) to low-erucic acid varieties has favoured the exploitation of Crambe as a source of erucic acid, this despite the presence of undesirable thioglucosides (e/ /-progoitrin) and a bitter alkaloid (sinapin). Treatment with ammonia combined with heat treatment removes these materials and increases the nutritive value of the meal (Kirk et al., 1966 Tookey et aL, 1980). 

In an earlier stndy, Josefesson and Uppstrom (1976) evaluated the influence of sinapine on the nutritional value of rapeseed meal and white mustard meal. However, the effect of sinapine was not highly significant. In another in vivo study, Pearson et al. (1980) found that sinapine did not reduce the ability of chicks or laying hens to oxidize trimethylamine. Since the amount included in the diet was similar to that which would be provided by a diet containing 10% rapeseed meal, it was concluded that sinapine is not involved in the depression of TM A oxidation that occurs when the meal is fed and acts solely as a source of TMA in the consequent production of egg taint. 

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