Tranchida P.Q.,Messina University |
Purcaro G.,Messina University |
Purcaro G.,University of Udine |
Visco A.,Messina University |
And 6 more authors.
Journal of Chromatography A | Year: 2011
The present investigation is focused on a simple flow modulator (FM), for comprehensive two-dimensional gas chromatography (GC × GC). The interface is stable at high temperatures, and consists of a metallic disc (located inside the GC oven) with seven ports, which are connected to an auxiliary pressure source via two branches, to the first and second dimension, to a waste branch (linked to a needle valve) and to an exchangeable modulation loop (2 ports). The ports are connected via micro-channels, etched on one of the inner surfaces of the disc. Modulation is achieved using a two-way electrovalve, connected on one side to the additional pressure source, and to the two metal branches, on the other. An FM enantio-GC × polar-GC method (using a flame ionization detector) was optimized (a 40-μL loop was employed), for the analysis of essential oils. As an example, an application on spearmint oil is shown; the method herein proposed was subjected to validation. Finally, an FM GC × GC diesel experiment was carried out, using an apolar-polar column combination, to demonstrate the effectiveness of the modulator in the analysis of a totally different sample-type. © 2010 Elsevier B.V.
Shibamoto S.,Shimadzu Corporation |
Gooley A.,SGE Analytical Science |
Yamamoto K.,Osaka Prefecture University
Lipids | Year: 2014
Using a strongly polar cyanopropyl capillary column we have investigated the gas chromatography (GC) separation behaviors of 24 octadecadienoic acid methyl ester (18:2ME) isomers compared against saturated methyl stearate (18:0ME) and arachidic acid methyl ester (20:0ME), and the dependency on the GC column temperature. The 24 isomers were obtained by performing cis-to trans-isomerization of six regioisomers: five of the 18:2ME isomers were prepared by the partial reduction of methyl α-linolenate and methyl γ-linolenate C18 trienoic acids with different double bond positions, whereas the sixth isomer, 18:2ME (c5, c9), was obtained from a raw constituent fatty acid methyl ester (FAME) sample extracted from Japanese yew seeds. There are no reference standards commercially available for 18:2ME isomers, and in elucidating the elution order of these isomers this study should help the future identification of cis- and trans-type of 18:2ME. We also report the identification method of cis- and trans-type of FAME using equivalent chain lengths and attempt the identification of cis- and trans-type of 18:2ME isomers from partially hydrogenated canola oil. © 2014 AOCS.
Candish E.,Australian Center for Research on Separation Science |
Gooley A.,Australian Center for Research on Separation Science |
Wirth H.-J.,SGE Analytical Science |
Dawes P.A.,SGE Analytical Science |
And 2 more authors.
Journal of Separation Science | Year: 2012
Microextraction by packed sorbent (MEPS) has been directly hyphenated with ESI-MS for the rapid screening of opiates and codeine metabolites in urine. This study introduces a novel format of MEPS that incorporates a two-way valve in the barrel of the syringe enabling the direction of liquid flow to be manipulated. Controlled directional flow (CDF) MEPS allows sharp, concentrated sample bands to be delivered directly to the MS in small volumes and effectively eliminates the need to optimize elution. The method optimization assessed the recovery, matrix effects, and the speed of infusion, all critical variables for optimum ESI performance. Matching extraction workflows demonstrated a reduction in carryover from 65% for conventional MEPS to only 1% for CDF MEPS. The recovery (<89% for 50 μL sample), matrix effects (<42%), linearity (r2 > 0.99), and LODs (<5 ng/mL) were determined to demonstrate method performance. The optimized approach was employed for the screening of codeine metabolites in urine. The ion trace revealed sharp sample bands corresponding to the codeine metabolites. At-line MEPS-ESI-MS allowed both sample preparation and analysis to be completed in only 5 min facilitating high throughput and alleviating the burden of method development. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.