Gas Phase Fragmentation of Sudan and d_(6)-labelled Sudan Azo Dyes

摘要

The detection of traces of azo dyes has become an important field in the analytical chemistry due to their high toxicity. In particular sudan azo-dyes are widespread used as colorants in cosmetics, foods, textiles commodities and in tattooing too. Various risks are expected for humans exposed to the action of this molecules. Mass spectrometry, and particularly tandem mass spectrometry, can play an important role in the analytical procedures that aim to detect and possibly quantify these substances. It is important, however, to understand the mechanism that rules the chemistry of sudan dyes in the gas phase. In this contribution the gas phase behavior of the sudan I, II, III, IV and para-red has been analyzed together with their labeled homologues deuterated in the naphtol moiety. The high resolution electrospray experiments were carried out in a hybrid Q-Star Pulsar-i mass spectrometer equipped with an ion spray ionization source. Samples were introduced by direct infusion (5 (mu)L/min) of the solution the appropriate azo-dye at a spray voltage of 4800 V. MS~(2) experiments were performed in the collision cell q on the isotopically pure (~(12)C) peak of the selected precursor scanning the time-of-flight (TOF) analyzer. The collision energy was set from 15 to 35 eV, depending on the compound. All the acquisitions were averaged over 60 scans at a TOF resolving power of 8000. The deuterated sudan compounds have been synthesized by a modified literature procedure.