Direct Quantification Technique for Natural Moisturizing Factor (NMF) in Stratum Corneum by DART-MS
Katsuyuki Maeno , and Haruo Shimada. Shiseido Global Innovation Center, Yokohama
Yasuo Shida, University of Yamanashi, Kofu, Japan
DART-MS is used for direct quantification of natural moisturizing factor (NMF) components in stratum corneum (SC), such as urea, pyrrolidone carboxylic acid, lactic acid and amino acids. NMF components play an important role in maintaining proper moisture levels in the SC. However, DART-MS has been considered not to be suitable for a quantitative analysis due to the matrix effects that are practically unavoidable in ambient ionization techniques . In this study, we have targeted amino acids as NMF and employed appropriate stable-isotope-labeled internal standards (SIL-IS) to overcome the quantitative problem of DART-MS. We have tried to develop a rapid, simple and quantitative analytical technique for NMF components.
Dopant-Assisted Direct Analysis in Real Time Ionization with Argon Gas
Robert B. Cody* and A. John Dane.
JEOL USA, Inc. 11 Dearborn Rd, Peabody MA 01960 USA
The Direct Analysis in Real Time (DART) ambient ionization source is commonly operated with helium or nitrogen gas causing direct ionization of the analyte, or indirect ionization through ion-molecule reactions involving atmospheric gases such as water and oxygen. With two exceptions in the literature, argon has not been used as a DART gas because the internal energies of metastable argon states are lower than the ionization energy of water and oxygen. Here we show that dopant-assisted argon DART follows mechanisms analogous to those proposed for dopant-assisted atmospheric pressure photoionization (APPI) and that common APPI dopants can also be used with argon DART. The ionization mechanism can be controlled by selecting dopants that favor charge exchange or proton transfer.
Inert-atmospheric solid analysis probe (ASAP): a new fast and easy way to characterize
air sensitive compounds by mass spectrometry
Mathilde Farenc, Carlos Afonso, Pierre Giusti
TOTAL Refining Company
- CNRS Joint Laboratory C2MC:
Complex Matrices Molecular Characterization, France
Metallocenes are used on an industrial scale for olefin polymerization
and are highly reactive toward moisture and
oxygen. The analysis of air sensitive molecules by mass
spectrometry (MS) is always a difficult task.
The principal challenge is to transfer the molecules from
the inert atmosphere to the source of the instrument. One
solution developed by Trefz at al., is to couple the mass
spectrometer to a glove box. The sample can be then infused
to the source using a syringe pump but glove boxes
are very rarely located close to mass spectrometers. Moreover
this method require to solubilize the sample with an
ESI compatible solvent.
We developed a new approach based on the atmospheric
pressure analysis probe (ASAP) that allows the transfer of
air sensitive samples and the transfer of air sensitive samples and their release directly into the source chamber.