Rapid Screening of Edible Oils Using Triacylglycerols and Fatty Acid Distributions

In their recent publication, Ambient mass spectrometry employing direct analysis in real time (DART) ion source for olive oil quality and authenticity assessment, Lukas Vaclavik et al have successfully demonstrated the authentication of different grade olive oils using the AccuTOF DART.

At IonSense, we performed a similar series of experiments with the goal of creating a reliable screening method for use on a low-resolution mass spectrometer, such as our Thermo-Finnigan LCQ Deca. Oils were sampled neat, by dipping the multi Dip-it holder into a 96-well plate filled with the oils. The module was then run through the DART's ionization region on the DART SVP's linear rail. The analysis 12 oil samples took approximately 5 minutes to complete.

Positive-ion spectra, seen below, show ammonia adducts of Triacylglycerols OOO OOP and OO and give clear chemical fingerprints of the different plant oils. Interestingly, the ammonia was present in the lab's atmosphere; no dopant was used to induce reactions.
Negative-ion spectra characterize the various acids present in olive oils, such as oleic and linoleic acids and allow differentiation between 100% pure olive oil and higher-grade extra virgin product.

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Reference

Direct Analysis in Real Time for Reaction
Monitoring in Drug Discovery
Chris Petucci, Jason Diffendal, David Kaufman, Belew Mekonnen, Gene Terefenko,‡ and Brian Musselman*
Discovery Analytical Chemistry and Medicinal Chemistry, Wyeth Research, Collegeville, Pennsylvania, and IonSense, Inc.*, Saugus, Massachusetts

Abstract

Direct analysis in real time (DART) is a novel ionization technique that provides for the rapid ionization of small molecules under ambient conditions. In this study, several commercially available drugs as well as actual compounds from drug discovery research were examined by LC/UV/ESI-MS and DART interfaced to a quadruple mass spectrometer. For most compounds, the molecular ions observed by ESI-MS were observed by DART/MS. DART/MS was also studied as a means to quickly monitor synthetic organic reactions and to obtain nearly instantaneous molecular weight confirmations of final products in drug discovery.

For simple, synthetic organic transformations, the trends in the intensities of the mass spectral signals for the reactant and product obtained by DART/ MS scaled closely with those of the diode array or the total ion chromatogram obtained by LC/UV/ESI-MS. In summary, DART is a new tool that complements electrospray ionization for the rapid ionization and subsequent mass spectral analysis of compounds in rug discovery.