Interfering fragments

The final possible mode of action for an antioxidant is as a peroxide decomposer. In the sequences that lead to photodegradation of a polymer the ready fragmentation of the hydroperoxide groups to free radicals is the important step. If this step is interfered with because the peroxide has undergone an alternative decomposition this major source of initiation is removed. The additives which act by decomposing hydroperoxide groups include compounds containing either divalent sulfur or trivalent phosphorus. The mechanism involves... 

Quite often a normal electron ionization mass spectrum appears insufficient for reliable analyte identification. In this case additional mass spectral possibilities may be engaged. For example, the absence of the molecular ion peak in the electron ionization spectrum may require recording another type of mass spectrum of this analyte by means of soft ionization (chemical ionization, field ionization). The problem of impurities interfering with the spectra recorded via a direct inlet system may be resolved using GC/MS techniques. The value of high resolution mass spectrometry is obvious as the information on the elemental composition of the molecular and fragment ions is of primary importance. 

This system resolved the aniline peak (retention time (rt) = 2.67 min) from the benzidine peak (rt = 2.27 min) as can be seen in Figure 2. Other potential interferences were selected for study by looking at the expected fragments from the reduction of various dyes. Reduced dye samples were spiked with aniline (rt = 2.67 min), -aminophenol (rt = 1.97 min), -phenylenediamine (rt = 1.93 min) and -nitroaniline (rt = 3 16 min). None of these materials interfered with the detection of the benzidine peak. To determine if other types of dyes might interfere with the analysis, two sets of filters were spiked at low and high levels separately with C.I. Direct Red 28 (13 7 yg and 137 yg), C.I. Direct Blue 53 formulation (o-tolidine-based) (21.2 yg and 212 yg) and C.I. Direct Blue 8 formulation (o-dianisidine-based)(23.3 yg and 233 yg). 

Kapron et al. (2005) showed that FAIMS can be used to selectively quantify an amine compound in the presence of an interfering N-oxide metabolite (Fig. 1.20). Under the conventional LC-MS/MS settings, a SRM based precursor/fragment... 

The full-scan BPC obtained from LTQ-FTICR LC-MS data does not display diclofenac or its monohydroxyl metabolite (Ml) that were spiked into rat bile sample due to the significant interference from ions of endogenous components in the bile (Fig. 6.9a). In contrast, MDF analysis of the LC-MS data file completely removed these interfering ions, resulting in a BPC that clearly exhibits only the drug and Ml (Fig. 6.9b). The same bile sample was analyzed with NLS and PIS using a triple-quadmpole instrument. Diclofenac lost a neutral fragment (46 Da) to form a major ion at m/z 250 under CID conditions (Fig. 6.8a). 

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