Olivier P Haefliger

  • Citations Per Year
Learn More
DART (Direct Analysis in Real Time) is an innovative technology to analyze complex solid samples at atmospheric pressure and ground potential by simply placing them between a DART ion source and a mass spectrometer. The analytes are ionized by a gun of neutral metastable species. The first examples of the application of DART to the analysis of flavor and(More)
In many analytical techniques, 1+1 resonance-enhanced multiphoton ionization (1+1 REMPI) is used because it is an efficient and optically selective soft ionization method. While 1+1 REMPI of jet-cooled molecules has been extensively studied, little has been reported so far about this mechanism as it is used in analytical techniques, that is, in the cases(More)
Two-dimensional HPLC was applied for the first time to the analysis of complex surfactant mixtures. In the first dimension, ion chromatographic-type separations were performed on a diol column eluted by an acetonitrile-water (0.1% trifluoroacetic acid) gradient. Using this new technique, cationic and amphoteric surfactants were not retained at all, nonionic(More)
Direct analysis in real time mass spectrometry (DART-MS) was used to monitor the release kinetics of a taste-refreshing compound from chewing gums into the saliva of subjects. A new DART-MS sample probe was designed which was about four times more sensitive than the current benchmark probe. This decreased the impact of the dilution of the saliva samples(More)
Directed evolution via iterative cycles of random and targeted mutagenesis was applied to the P450 domain of the subterminal fatty acid hydroxylase CYP102A1 of Bacillus megaterium to shift its regioselectivity towards the terminal position of palmitic acid. A powerful and versatile high throughput assay based on LC-MS allowed the simultaneous detection of(More)
We used a double-jet mixer to encapsulate water-soluble polyphenols, green tea extract (GTE), with calcium-based inorganic materials. The device mixed calcium chloride solutions with a solution of carbonate and phosphate in the presence of a GTE solution, and formed micro-particles which capture the GTE molecules. The micro-particles were analysed by liquid(More)
A method was developed for the quantification of 5-α-androst-16-en-3-one in human breast milk based on application of a stable isotope dilution assay using 5α-androst-16-en-3-one-6, 6-d(2). The procedure includes extraction of the human milk by hexane with subsequent clean-up of the obtained extract by gel permeation and silica gel column chromatography.(More)
The influence of structural and physico-chemical parameters on the release of a volatile tertiary alcohol (2-methyl-1-phenyl-2-propanol) by neighbouring-group-assisted cyclisation of 2-carbamoylbenzoates at neutral pH was investigated by comparing the covalent-bond cleavage from the surface of linear, comblike poly(propylene imine) "stylomers" and their(More)
Extracts of Toona sinensis shoots were studied to identify the precursors of volatile sulfur-containing flavor molecules. T. sinensis was found to contain new compounds (S,S)-γ-glutamyl-(cis-S-1-propenyl)thioglycine, 1, (S,S)-γ-glutamyl-(trans-S-1-propenyl)thioglycine, 2, and γ-glutamyl-(cis-S-1-propenyl)-cysteine, 3. The structures of these compounds were(More)
An innovative headspace sampling and injection system for gas chromatography was designed using a longitudinally modulating cryogenic system mounted around the sampling loop of a two-position loop injector. The setup was hyphenated to a fast low thermal mass gas chromatograph, allowing transient concentrations of semivolatile analytes to be monitored in(More)