Rapid analysis of lubricants by atmospheric solid analysis probe-ion mobility mass spectrometry.

Formulated lubricants are complex mixtures composed of base oil(s) and additives with various functions (detergents, corrosion inhibiter, antioxidant, viscosity modifiers, etc.). Because of the aliphatic nature of base oil and the chemical diversity of additives, the characterization of lubricant is currently a long and complex process.

Exploration of polyamide structure-property relationships by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Rationale: Polyamides (PA) are among the most used classes of polymers because of their attractive properties. Depending on the nature and proportion of the co-monomers used for their synthesis, they can exhibit a very large range of melting temperatures (Tm ). This study aims at the correlation of data from mass spectrometry (MS) with differential scanning calorimetry (DSC) and X-ray diffraction analyses to relate molecular structure to physical properties such as melting temperature, enthalpy change and crystallinity rate.

Tandem mass spectrometry of low solubility polyamides.

The structural characterization of polyamides (PA) was achieved by tandem mass spectrometry (MS/MS) with a laser induced dissociation (LID) strategy. Because of interferences for precursor ions selection, two chemical modifications of the polymer end groups were proposed as derivatization strategies. The first approach, based on the addition of a trifluoroacetic acid (TFA) molecule, yields principally to complementary bn and yn product ions.

Atmospheric solid analysis probe-ion mobility mass spectrometry of polypropylene.

Polyolefin, including polypropylene (PP), constitutes an important class of materials. In particular, the recent interest in recycling plastic wastes necessitates their characterization as well as their degradation mechanism being understood. PP materials characterization by mass spectrometry, including polymer and additives parts, is not direct and generally involves a pyrolysis step to produce ionizable species.

Successful MALDI-MS analysis of synthetic polymers with labile end-groups: the case of nitroxide-mediated polymerization using the MAMA-SG1 alkoxyamine.

A sample pretreatment was evaluated to enable the production of intact cationic species of synthetic polymers holding a labile end-group using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. More specifically, polymers obtained by nitroxide-mediated polymerization involving the MAMA-SG1 alkoxyamine were stirred for a few hours in trifluoroacetic acid (TFA) to induce the substitution of a tert-butyl group on the nitrogen of nitroxide end-group by a hydrogen atom. Nuclear magnetic resonance, electrospray ionization tandem mass spectrometry, and theoretical calculations were combined to scrutinize this sample pretreatment from both mechanistic and energetic points of view.

Solvent-based and solvent-free characterization of low solubility and low molecular weight polyamides by mass spectrometry: a complementary approach.

Rationale: Polyamides (PA) belong to the most used classes of polymers because of their attractive chemical and mechanical properties. In order to monitor original PA design, it is essential to develop analytical methods for the characterization of these compounds that are mostly insoluble in usual solvents.

Methods: A low molecular weight polyamide (PA11), synthesized with a chain limiter, has been used as a model compound and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

Acquisition strategy to obtain quantitative diffusion NMR data.

Pulsed Gradient Spin Echo (PGSE) diffusion NMR experiments constitute a powerful tool for analyzing complex mixtures because they can in principle separate the NMR spectra of each mixture component. However, because these experiments intrinsically rely on spin echoes, they are traditionally regarded as non-quantitative, due to the signal attenuation caused by longitudinal (T(1)) and transverse (T(2)) nuclear magnetic relaxation during the rather long delays of the pulse sequence. Alternatively to the quantitative Direct Exponential Curve Resolution Algorithm (qDECRA) approach proposed by Antalek (J.

A convenient method for the measurements of transverse relaxation rates in homonuclear scalar coupled spin systems.

A new solution-state NMR method is proposed to determine apparent transverse NMR relaxation rates in both weakly and strongly scalar coupled two-spin systems.

Molecular weight determination of block copolymers by pulsed gradient spin echo NMR.

Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (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.

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples.

Solid-state Nuclear magnetic resonance (NMR) was used here to explore structural characteristics of samples to be subjected to matrix-assisted laser desorption/ionization (MALDI) and prepared without the use of any solvent. The analytical systems scrutinized in NMR were mixtures of a 2,5-dihydroxybenzoic acid (2,5-DHB) matrix and caesium fluoride (CsF), used as the cationization agent in synthetic polymer MALDI mass analysis, at different molar ratios (1:1, 5:1, and 10:1). Complementary information could be obtained from 13C, 133Cs, and 19F NMR spectra.