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Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spcctrometry (MS) is the technique of choice to achieve molecular weight data for synthetic polymers. Because the success of a MALDI-MS analysis critically depends on a proper matrix and cation selection, which in turn relates closely to the polymer chemical nature and size, prior estimation of the polymer size range strongly helps in rationalizing MALDI sample preparation. We recently showed how pulsed gradient spin echo (PGSE) nuclear magnetic resonance could be used as an advantageous alternative to size exclusion chromatography, to rationalize MALDI sample preparation and confidently interpret MALDI mass spectra for homopolymers. Our aim here is to extend this methodology to the demanding case of amphiphilic block copolymers, for which obtaining prior estimates on the [M.sub.w] values appears as an even more stringent prerequisite. Specifically, by studying poly(ethylene oxide) polystyrene block copolymers of distinct molecular weights and relative block weight fractions, we show how PGSE data can be used to derive the block [M.sub.w] values. In contrast to homopolymers, such determination requires not only properly recorded calibration curves for each of the polymers constituting the block copolymers but also an appropriate hydrodynamic model to correctly interpret the diffusion data.

This study shows how mass spectrometry and pulsed gradient spin--echo (PGSE) nuclear magnetic resonance can be advantageously combined to achieve more reliable molecular weight information for polymers. Specifically, PGSE was shown to be a convenient tool for a rapid evaluation of [M.sub.w] values to be further used as guidelines in matrix-assisted laser desorption/ionization (MALDI) sample preparation. PGSE calibration curves, established under given experimental conditions, were shown to be particularly robust, as they could be applied satisfactorily on different commonly available NMR instruments and different time frames. PGSE results were shown to compare well with size exclusion chromatography data used as a reference to validate this alternative technique. Moreover, because PGSE is relatively fast, it can be used interactively with MALDI analysis to check and understand mass spectrum profiles. This approach was first tested on poly(methyl methacrylate) (PMMA) standards and then successfully applied to determine the molecular weight of two unknown samples, a PMMA and a poly(ethylene glycol) monomethacrylate polymer.

5-(Cholesteryloxyethoxyphosphoryl)-5-methylpyrroline N-oxide (5-ChEPMPO), a DEPMPO analogue bearing a cholesterol group on the phosphorus atom, is prepared and used to trap peroxyl-, alkoxyl-, thiyl-, and carbon-centered radicals in organic solvent. The 5-ChEMPO-OOL spin adduct is observed by ESR and confirmed by ESI-MS/MS experiments.

A novel developed strategy for the synthesis of poly(amino)ester dendrimers is described. The process is developed on the basis of active cyanomethyl ester intermediates and an iteration of four consecutive steps of deprotection, activation, transesterification and scavenging.

A dynamic combinatorial selection approach was used to quantitatively obtain from trivial building blocks a structurally complex organic material in which carbon dioxide is reversibly but covalently incorporated as a guest with a mass content of 20%. The thermodynamic selectivity of the adduct, combined with the reversible nature of the system, provide pure molecular building blocks after a simple chemical disconnection to promote C[O.sub.2] as a green auxiliary to purify polyaldehyde or polyamine from mixtures of homologous structures.

Atmospheric pressure chemical ionization is employed for direct air analysis, without ion source modification, by using the sheath gas as the sample transport agent. A simple modification of the sheath gas inlet line allows introduction of gaseous samples into a commercial atmospheric pressure chemical ionization source. Optimization and testing of this novel air sampling method are described and detection of semivolatile compounds is shown. The analytical performance of the technique is established with methyl salicylate, including a limit of quantification of 100 pptr, a limit of detection of 50 pptr, a linear response from 100 pptr to 20 ppb, and rise and fall times of 12 and 20 s, respectively. Using reagent ion monitoring, it is shown that the protonated methanol dimer is the principal CI reagent ion leading to protonated dimethyl methylphosphonate, while the monomer is mainly responsible for protonating methyl salicylate. Since the formation of the CI reagent (methanol clusters) can be controlled by simple variation of experimental parameters, the selectivity of the method can be easily adjusted to suit the targeted analyte. Performance is found to be independent of the choice of air or nitrogen as the sheath gas (and thus as the sample matrix) and this, together with the sensitivity and speed of the technique, make it promising for field studies.