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Van der Linden, W. E.; Poppe, H. Anal. Chim. Acta 1981, (23) Reijn, J. M.; Van der Linden, W. E.; Poppe, H. Anal. Chim. Acta 1981, (24) Engelhardt, H.; Neue, U. D. Chromatographla 1982, 75, 403-408. (25) Selavka, C. M.; Jiao, K.; Krull, I. S. Anal. Chem. 1987, 5 9 , 455. 95-104. YO&, 1980 pp 207-316. 583-598. 123, 229-237. 726, 1-13. 2221-2224. (26) Korenaga, T.; Shen, F.; Yoshida, H.; Takahashi, T.; Stewart, K. K.A method has been developed for the characterlzatlon of that class of preservatlve compounds that release formaldehyde as their prlmary mode of biologlcal actlvity. This method incorporates a derivatlzation step specHlc to molecular methyloi functlonalitles and formaldehyde following a separation of the preservatlve compounds by high-performance liquid chromatography (HPLC). The derlvatlve thus produced dtsplays a characterlstlc absorbance at 410 nm and fluorescence at 510 nm. The study compounds, which typically exhibit no characterlstlc absorbance or fluorescence, are thereby rendered detectable by elther of these phenomena. The postcolumn approach used in this study circumvents the labor-lntenslve step of batch derlvatization and, more Importantly, It allows for the speclatlon of lndlvldual preservatlve compounds in a mixture containlng not only other preservatives but also free formaldehyde. The study compounds range in polartty from essentially nonpolar to catlonk, Le. quaternary ammonlum salts. The HPLC separatlon step was therefore conflgured in a mixed mode, progressing from a typlcai reversebphase eluant proflie to a cation exchange eluant proflie vla a ternary gradient. The method detection limn Is ca. 400 ppb and the linear dynamic range Is 2 orders of magnitude. The relatlve standard deviation Is around 0.5 %, and accuracy Is 100 % , withln precislon.

The reactions of «-alkyl halides on clean titanium metal and on hydrohalided titanium surfaces have been studied. With the exception of alkyl fluorides, the «-alkyl halides react stoichiometrically with titanium at a conveniently measurable rate in the temperature range 150-250°, yielding olefin and a minor amount of paraffin in the gas phase, and a titanium hydride-halide phase at the surface. These latter reactions all followed a halforder rate law for disappearance of reactant. The reactivity of «-propyl fluoride was several orders of magnitude greater than that of the other «-propyl halides, and the reaction was first order in reactant. The activation energies for the reactions of «-propyl fluoride, chloride, bromide, and iodide were 20.5, 23.5, 27.5, and 29.5 kcal/mol, respectively. A mechanism is proposed to explain these experimental observations.

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This paper describes the design and operation of a time-of-flight mass spectrometer that uses fast, heavy ions from the spontaneous fission of Cf-252 to desorb species from the surfaces of solids. The technique provides for a simultaneous, multimass, isotope specific, elemental, and molecular surface characterization without complications due to surface charging.