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.