Differences in the chromatographic and mass spectral properties of 3,3′,5,5′-tetrachlorodiphenoquinone and 2,3,7,8-tetrachlorodibenzo-p-dioxin

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Abstract
Tetrachlorodiphenoquinones have the same exact mass and elemental composition as the toxic environmental contaminant 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin. However, analysis of 3,3′‐5,5′‐tetrachlorodiphenoquinone showed a pronounced tendency toward chemical reduction in the mass spectrometer to the quinol compound, producing a molecular ion two mass units higher than 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin. Distinct differences were also apparent between the mass spectral fragmentation patterns of 3,3′,5,5′‐tetrachlorodiphenoquinone and 2,3,7,8‐tetrachloridibenzo‐p‐dioxin. The 3,3′,5,5′‐tetrachlorodiphenoquinone spectrum shows a successive loss of carbon monoxide, with the most prominent fragment corresponding to loss of two molecules of carbon monoxide plus chlorine. In the mass fragmentation of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin carbon monoxide loss is suppressed, but loss of one molecule of carbon monoxide plus chlorine is a major fragment ion. During an alumina column clean‐up procedure 3,3′,5,5′‐tetrachlorodiphenoquinone did not coelute with the fraction containing 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin. This evidence indicates that tetrachlorodiphenoquinones are unlikely to interfere with mass spectrometric determination of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin in environmental samples.