Photoelectron resonance capture ionization mass spectrometry of fatty acids in olive oil

Abstract

Photoelectron resonance capture ionization (PERCI) mass spectrometry has been developed for the direct online analysis of organics, including lipids. Analysis is conducted without the need for sample preparation or chemical derivatization such as methylation, foregoing the use of harmful or toxic chemicals. PERCI is currently being adapted towards the analysis of edible oils. Herein, as a proof of principle of the simplicity and potential utility of this method towards the analysis of edible oils, we present the analysis of the prevalent fatty acids ( . Similarly, the PERCI mass spectrum of ozonized olive oil showed all the anticipated ions of the predominant FA, oleic acid, as well as many molecular ions arising from less abundant unsaturated FA.

The ozonolysis of primary aliphatic amines in fine particles

“…Two modes of ionization have been described with near 0 eV photoelectron attachment to organic molecules, namely associative (or non-dissociative) and dissociative electron attachment. In associative electron attachment a low energy photoelectron attaches to the molecule without any fragmentation of the analyte in the ionization process; whereas, dissociative electron attachment results in the loss of an atomic or molecular fragment concomitant to ionization of the analyte Zahardis et al, 2005Zahardis et al, , 2006c.…”

“…The flow rate in the reactor was held constant at 0.9 L min −1 , such that positioning the aerosol injector from 1 to 51 cm from the end of the flow reactor resulted in reaction times from 0 to 17 s. Ozone was generated from USP Medical Air (UN1002, Airgas East, Williston, VT) or USP Oxygen (UN1072, Airgas East, Williston, VT) below and above 1×10 −4 atm respectively, by high frequency corona discharge (OL80A/DLS, OzoneLab, Burton, BC, Canada) and quantified spectrophotometrically as described in an earlier report (Zahardis et al, 2006c). Particles entered the PERCI AMS through a 260 µm critical orifice giving a flow rate of 0.5 L min −1 and were introduced into the mass spectrometer through a differentially pumped particle inlet and focused into a beam using a series of aerodynamic lenses described elsewhere (Petrucci et al, 2000;Liu et al, 1995b, a).…”

“…These amides would have an alkyl end, unlike the amides arising from the reaction of SCI-1 which have a carboxyl group functionality. It is likely that SCI-2 does form amides with these amines, but they are not ionized to any significant extent with ∼0 eV electrons, as is the case with all organic acids (LaFranchi and Petrucci, 2006;Zahardis et al, 2005Zahardis et al, , 2006c investigated to date. The high molecular weight, nitrogen-containing products measured and their corresponding assignments are summarized in Table 1. 3.4 Ozonolysis of ODA (HDA) + OL in mixed particles:…”

The oleic acid-ozone heterogeneous reaction system: products, kinetics, secondary chemistry, and atmospheric implications of a model system – a review

“…Very recently, complex OA such as meat-cooking (Hearn and Smith, 2006) and olive oil aerosols (Zahardis et al, 2006c), both with high OL content, have been evaluated. Both monodisperse and polydisperse aerosols have been interrogated.…”

“…Some of these products are summarized in Table 1. Recently this method has been applied to the analysis of the ozonolysis products of linolenic acid (LN) and olive oil (Zahardis et al, 2006c), a complex mixture of both saturated and unsaturated FA. n/a n/a n/a n/a increase in water uptake at 95% relative humidity n/a n/a n/a n/a increase in CCN activity but only for high ozone exposure …”