Variation of retention index of a solute due to the presence of a large neighboring peak

Yin, Hongxi; Zhu, Yifan; Sun, Yongqi

doi:10.1007/bf02261069

Cited by 6 publications

(1 citation statement)

References 13 publications

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“…Small variations in retention times were attributed to random errors and matrix effects. For example, there is documented evidence that small peaks eluting in the neighborhood of a large peak are subject to largeneighboring peak effects, which cause them to elute somewhat differently [20]. It has been hypothesized that the smaller peaks see a stationary phase that is a mixture of the real or original stationary phase and the large peak.…”

Section: -01mentioning

confidence: 99%

Chemical ionization mass spectrometry and gas chromatographic identification of some nitrogen‐containing volatile compounds from large‐scale pyrolysis of poly (acrylonitrile‐butadiene‐styrene) plastics

Shapi

Riekkola

1992

J Microcolumn Separations

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Abstract. A number of volatile pyrolyzates of large-scale thermolysis of ABS and SAN plastics, which include phenyl substituted aliphatic nitriles and dinitriles, have been tentatively identified by GC-MS. The exact isomers of most of these compounds have, however, not been specified, owing to limitations of 70 eV electron ionization (EI) mass spectrometry and temperature-programmed retention indices in the absence of model compounds. In this study, some of the isomeric forms of these compounds were clarified using chemical ionization (CI) mass spectrometry and capillary gas chromatography (GC) involving model compounds. The presence of phenylacetonitrile, 2-phenylpropanenitrile, 3-phenylpropanenitrile, trans-3-phenyl-2-propenenitrile, and 4-phenylbutanenitrile among the pyrolyzates was confirmed by GC. Isobutane and methane CI of the nitriles yielded intense MH' and adduct ions of low to medium intensity. Most of the smaller phenyl substituted nitriles tended to fragment by loss of 27 mass units, attributed to HCN. Isobutane CI of the larger molecules produced more fragmentation than methane CI which yielded little or no fragmentation. The reliability of the CI spectra was limited to the role of providing molecular formula information and some indirect evidence for the presence of the nitrile group in the molecules.Key words: gas chromatography-mass spectrometry, nitrogen-containing pyrolyzates, ABS, SAI?, isobutane, methane chemical ionization INT.RODUCTIONPrimary or secondary pyrolyzates of large-scale thermoly sis of poly(acrylonitri1e-butadiene-styrene) (ABS) and poly(acrylonitri1e-styrene) (SAN) plastics, tentatively identified by GC-MS, include a number of volatile nitrogen-containing compounds among others. Each of these phenyl substituted saturated or unsaturated aliphatic nitriles and dinitriles has a chain up to 7 carbon atoms in length in the molecular weight range of 53 to 261 [1,2]. The exact isomers of most of these compounds were, however, not specified, owing to the well known limitations inherent in 70 eV electron ionization (EI) mass spectrometry (MS) and temperature-programmed gas chromatography (GC) retention indices in the absence of model com-*Author to whom correspondence should be addressed 1992 MicroSeparations pounds. The 70 eV EI ions of isomers tend to undergo molecular rearrangement via a common ionic structure, resulting in indistinguishable spectra [3]. This study was aimed at clarifying the isomeric forms of some of the observed compounds by isobutane and methane chemical ionization (CI) MS and GC using model compounds. The CI experiments yielded reliable molecular formula information and provided some indirect evidence for the presence of the nitrile group in the molecular structures. Retention agreement was obtained on SE-54 and SP-2330 columns for the phenyl substituted nitriles. Peak splitting attributed to band broadening in space interfered with analysis of the small unsubstituted nitriles on SE-54.

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Section: -01mentioning

confidence: 99%