The natural river water certified reference material SLRS‐4 (NRC‐CNRC, National Research Council‐Conseil National de Recherches Canada) has been routinely analysed for major and trace elements by six French laboratories. Most measurements were made using inductively coupled plasma‐mass spectrometry. For silicon and thirty one trace elements (rare earth elements, Ag, B, Br, Cs, Ga, Ge, Li, P, Pd, Rb, Se, Th, Ti, Tl, W, Y and Zr), no certified values are assigned by NRC‐CNRC. We propose some compilation values and related uncertainties according to the results obtained by the different laboratories.

The negative-ion mass spectra of arylazo sulfides ArNNSR (1) show that their radical anions (1 •-), in competition with the fragmentation to aryl radicals, nitrogen, and thiolate anions, generate the radical anions of the corresponding sulfides (ArSR•-) and/or fragments therefrom. The competition between the two pathways above depends on the nature of the aryl moiety (possible presence and strength of electron-withdrawing substituents), on the nucleophilicity of the thiolate fragment, and on the stereochemistry [(E)- or (Z)-configuration] of the starting arylazo sulfide. The results are best interpreted through the possibility that 1 •- leads to ArSR•- through an electrostatically bonded thiolate ion−aryldiazenyl radical complex, in competition with dissociation of such a complex into separated species. A comparison with previous results on electrochemically induced reactions of 1 suggests that ion−radical pairs are key intermediates both in gas-phase and in solution.

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The low-energy collision-activated dissociation of symmetrical n-butyl-substituted and of allyl-substituted onium cations has been recorded using fast atom bombardment ionization and a tandem mass spectrometry quadrupole mass spectrometer. Structure of the fragments and decomposition pathways have been ascertained using a multiquadrupole MS/MS/MS triple analyser instrument. Whereas most sulphonium cations exhibit only heterolytic cleavages, fragmentation of ammonium and phosphonium is mainly homolytic. Allylic sulphonium, and to a lesser extent allylic ammonium, easily undergo propene elimination. This reaction, which does not occur in 1-propenyl oniums, might involve a McLafferty type rearrangement.