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Silicon speciation in environmental, biological and industrial matrices is of considerable importance due to its wide use in many consumer and personal care products and industry. In addition, the entry of silicones in various compartments like wastes, soils, air and water highlights the need to perform exposure studies, toxicological surveys and to measure negative effects. Due to possible contamination and trace level presence of silicon compounds, challenges to determination, identification and quantification are presented. The principal species of concern include siloxanes, silanols, silanediols and silanes. State of the art of analytical methods for total silicon determination and silicon speciation are established. Atomic spectroscopic methods are mainly used to measure total Si at trace concentration levels. On the opposite, hyphenated techniques are performed for Si speciation. Particular attention is paid to chromatographic methods coupled to sensitive and selective detectors (MS, AED and ICP) allowing structural information. Liquid and gas chromatography emerge as the most widespread separation techniques. However, other procedures such as MS, NMR, IR and XRF enable a better knowledge of these species. The potential and limitations of hyphenated techniques are highlighted, particularly concerning sensitivity and selectivity. Furthermore, potential sources of contamination and analytical artifacts in silicon determination are reviewed.

International audienceIon mobility-mass spectrometry is starting to be considered as a useful tool in the deconvolution of complex oil and petroleum samples. While ultrahigh resolution mass spectrometry is the incumbent technology in this field, ion mobility offers complementary information related to species size and shape, and also the ability to resolve structural isomers. In this work, a sample of the resins portion of the Saturates, Aromatics, Resins, and Asphaltenes (SARA) fractions of crude oil was analysed using an orthogonal acceleration quadrupole time-of-flight mass spectrometer (oa-QToF MS) that incorporates a travelling wave ionmobility spectrometry (TWIMS) region. The ion mobility data were compared with previously acquired ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) data and various nitrogen containing families were identified. Ion mobility data were processed in the typical way for the oil and petroleum industry; and the use of high resolution exact mass coupled with mobility data to provide enhanced species resolution was examined. Double bond equivalence (DBE) and carbon number groups were identified using patterns in the ion mobility data, which demonstrated the utility of ion mobility for discovering species relationships within the crude oil sample. The ability to calibrate the ion mobility cell and generate sizes for the detected ions was also recognised as potentially having particular value for the implementation of conversion or hydrotreatment processes in the oil industry

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