Vanderléa de Souza

Single-Shot Biodiesel Analysis: Nearly Instantaneous Typification and Quality Control Solely by Ambient Mass Spectrometry

Using a simple and easily implemented desorption/ionization mass spectrometry technique, a tiny droplet of biodiesel placed on the surface of a sheet of paper is analyzed directly and nearly instantaneously under ambient conditions. No pre-separation or sample preparation is required, and clean mass spectra are obtained with great simplicity. In the positive ion mode, easy ambient sonic-spray ionization mass spectrometry, EASI(+)-MS, provides typical profiles of the major components of biodiesel samples, that is, either methyl esters (FAME) or ethyl esters (FAEE) of the natural fatty acids and triglycerides (TAG) from residual oil or oil from adulteration. Each FAME (FAEE) or TAG molecule is detected as a single sodiated molecule, [M + Na] (+) with relative intensities that correlate well with the known fatty acid profiles of the oil. Using EASI(-)-MS, typical and complementary profiles of free fatty acids (FFA) are obtained, which are detected in their deprotonated forms [FAA - H] (-). A general, single-shot approach for biodiesel analysis is therefore described, and samples from different feedstocks, from blends with petrodiesel, or from either methanol or ethanol trans-esterification are readily typified and major parameters of quality accessed.

Analysis of fuels via easy ambient sonic-spray ionization mass spectrometry.

The desorption and ionization of analytes directly from surfaces or natural matrices under ambient conditions has greatly simplified chemical analysis by mass spectrometry. Among the currently available set of such techniques, easy ambient sonic-spray ionization (EASI) is one of the simplest and most easily implemented. Fuels are among the most important and most complex classes of chemical mixtures and a challenge for fast and comprehensive chemical analysis. This review summarizes the applications of EASI-MS for fast, simple and nearly sample-preparation-free analysis of various fuels, focusing in typification, adulteration and quality control.

Used Frying Oil: A Proper Feedstock for Biodiesel Production?

Used frying oil seems to be an economically viable and environmentally attractive alternative for biodiesel production, but the acceptance and successful use of this and other biodiesels obtained from waste materials require careful evaluation of its fuel properties and impurities. Herein, we show that biodiesel made from used frying soybean oil display overall quality comparable to those obtained from the fresh oil as measured by standard parameters of fuel quality such as induction period, acid number, heat of combustion, and iodine value as well as at the molecular level via profiles of intact and oxidized fatty acid methyl esters. These profiles were obtained directly from the biodiesel samples by easy ambient sonic spray ionization mass spectrometry. An artificial antioxidant, N,N′-di-sec-butyl-p-phenylenediamine, was shown to significantly increase the oxidative stability of the used frying oil biodiesel at trace level.

Intrinsic Mobility of Gaseous Cationic and Anionic Aggregates of Ionic Liquids

Travelling-wave ion mobility mass spectrometry was used to measure the intrinsic mobility of a series of gaseous supra-cation and supra-anion aggregates of several ionic liquids. Close mobilities were observed in a T-wave cell filled with helium at ca. 0.8 mbar for [(DAI)(n+1)(X)(n)](+) (DAI is the 1,3-dialkylimidazolium cation and X is the anion) as compared to the respective anions [(DAI)(n)(X)(n+1)](-) for n=0 to 9. The anomalous behavior reported before in the condensed phase seems therefore to be related to the unique structural organization of pure ionic liquids that provides both polar and non-polar regions with directionality in which the anionic species are more retained than the cationic species in the salt network.

Blends of soybean biodiesel with petrodiesel: direct quantitation via mass spectrometry

Quantitation and identification of blends of soybean biodiesel with petrodiesel were performed via mass spectrometry using two ionization techniques: electrospray ionization (ESI) and Venturi easy ambient sonic-spray ionization in its liquid mode (VL-EASI). Different soybean biodiesel/petrodiesel blends (from B0 to B100) were diluted and then directly infused and analyzed by both techniques. To investigate adulteration of Bn blends, different soybean oil/biodiesel and soybean oil/petrodiesel blends were analyzed. Analytical curves were obtained in three replicates. The two techniques were shown to provide reasonably accurate quantitation in the B1-B20 range. These techniques were also successfully used to detect contamination or adulteration of Bn blends with vegetable oils. ESI is a widely used and commercially available technique whereas a VL-EASI source can be easily mounted using common laboratory parts requiring no use of high voltages. Both techniques require no pre-separation or derivatization steps and offer, therefore, simple and fast methods for the quantitation of Bn blends. The comprehensive snapshots of the molecular composition also allow quality control and typification of the biodiesel and eventually of the vegetable oils in illegal admixtures.

Using the L/O ratio to determine blend composition in biodiesel by EASI-MS corroborated by GC-FID and GC-MS

Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is applied to the analysis of biodiesel blends prepared from soybean and animal fat biodiesel. A correlation was established between the ratio of abundance of linoleic acid (L) and oleic acid (O) methyl ester ions with the biodiesel blend composition. To compare these results from the EASI-MS technique, the L/O ratio of these blends was also determined using both gas chromatography with flame ionization detection (GC-FID) and gas chromatography with mass spectrometry (GC-MS). Both these classical techniques confirmed that the ratio between the mass fraction of FAME from L and O as measured by EASI-MS is indeed correlated with the blend composition of soybean–animal fat biodiesel.