25 research outputs found
Enhanced resolution comprehensive two-dimensional gas chromatography applied to the analysis of roasted coffee volatiles
No full textThe present research is based on the full exploitation of the separation power of a 0.05mm internal
diameter (ID) capillary, as a comprehensive two-dimensional (2D) GC (GC×GC) secondary column, with
the objective of attaining very high-resolution second dimension separations. The aim was achieved by
using a split-flow system developed in previous research [P.Q. Tranchida, A. Casilli, P. Dugo, G. Dugo,
L. Mondello, Anal. Chem. 79 (2007) 2266], and a dual-oven GC×GC instrument. The column combination
employed consisted of a polar 30m×0.25mm ID column connected, by means of a T union, to a
detector-linked high-resolution 1.1m×0.05mm ID apolar analytical column and to a 0.33m×0.05mm
ID retention gap; the latterwas connected to a manually operated split valve. As previously demonstrated,
the use of a split valve enables the regulation of gas flows through both analytical columns, generating the
most appropriate gas linear velocities. Comprehensive 2D GC experiments were carried out on Arabica
roasted coffee volatiles (previously extracted by means of solid-phase microextraction) with the splitvalve
closed (equal to what can be defined as conventional GC×GC) and with the split-valve opened at
various degrees. The reasons why it is absolutely not effective to use a 0.05mm ID column as second
dimension in a conventional GC×GC instrument will be discussed and demonstrated. On the contrary,
the use of a 0.05mm ID column as second dimension, under ideal conditions in a split-flow, twin-oven
system, will also be illustrated and discussed
Analisi degli acidi grassi di campioni lipidici tramite gascromatografia a separazione multidimensionale con micro modulatore a flusso (FM-GCxGC-qMS)
No full textA flexible chip-based pneumatic modulator for comprehensive two-dimensional gas chromatography
No full textGeneral principles and history
No full textDetailed information on the composition of mixtures is crucial in many areas of modern life. Chromatographic techniques are one of the key techniques applied to answer questions on what is in a mixture and how much of each constituent is present. Gas chromatography (GC) is a very powerful separation method that can separate highly complex mixtures into its constituents, but unambiguous identification is difficult to obtain without the coupling to a sensitive mass spectrometer (MS). For optimum performance of hyphenated GC-MS, the requirements and performance characteristics of both techniques need to be considered and properly balanced. In this chapter the various parameters that are relevant for the coupling of GC and MS will be defined. In the hands of a well-trained analyst the technique is today more powerful than it has ever bee
Enhanced selectivity and sensitivity of comprehensive two-dimensional gas chromatography combined with a novel high-speed triple quadrupole mass spectrometer
No full textChapter 10: Chemometrics: Basic principles and applications
No full textThis chapter will be devoted to chemometrics in the multivariate design of the experiments and in data treatment in gas chromatography. Basic principles will be given on the most commonly used approaches, along with applications in the field of one-dimensional and multidimensional gas chromatography. This chapter shows how suitable multivariate statistical methods can be of great support in specific food applications such as confirmation of authenticity, geographical origin, quality, evaluation of technological processes, and so on, exploiting its potential also in the omics field, such as "foodomics"
ENHANCED SELECTIVITY AND SENSITIVITY OF COMPREHENSIVE 2D GC COMBINED WITH A NOVEL FAST TRIPLE-QUAD MASS SPECTROMETER
No full textComprehensive two-dimensional gas chromatography (GC×GC), combined with mass
spectrometry (MS), is an extremely powerful three-dimensional technology, which has found
use only over the last decade. Very narrow peaks are generated in GC×GC applications, and
so MS systems must possess fast acquisition frequencies. For such a reason, low-resolution
high-speed time-of-flight (ToF) systems have been the most popular choice in the field, followed
by rapid-scanning single quadrupole (q) instruments. The main scopes of most such GC×GCToF
MS and GC×GC-qMS applications, have been the quantitative and/or qualitative analysis
of untargeted solutes. There has been only a low number of cases in which other MS-types
have been employed, a fact related to their slow spectral production rates. The present
investigation is focused on the use and first evaluation of a novel high-speed triple quadrupole
(QqQ) mass spectrometer, in flow-modulated GC×GC applications. The QqQ MS instrument
can be operated simultaneously in the full scan and multiple reaction monitoring (MRM) modes,
under the high spectral production frequencies required for GC×GC quali/quantitative
determinations. It will be shown that, in the same GC×GC-QqQ MS application, both full-scan
spectra relative to unknown compounds, and MS-MS data relative to known ones, can be
attained, killing two birds with one stone. Obviously, a great increase both in sensitivity and
selectivity were attained in the MRM mode. GC×GC-QqQ MS applications on real-world food
samples, containing contaminants at the sub-ppb level, will be illustrated and discussed
INCREASING THE SELECTIVITY AND SENSITIVITY OF COMPREHENSIVE TWO- DIMENSIONAL GAS CHROMATOGRAPHY BY HYPHENATION WITH A NOVEL HIGH- SPEED TRIPLE-QUADRUPOLE MASS SPECTROMETER
No full textComprehensive two-dimensional gas chromatography (GC×GC) has been widely used in
combination with mass spectrometry (MS), only throughout the last decade. With regards to
the mass-spectrometric instrumentation type used, low-resolution high-speed time-of-flight
(ToF) systems have been the most popular choice, followed by rapid-scanning low-resolution single quadrupole instruments. The main objectives of most such GC×GC-MS applications have been the quantitative and/or qualitative determination of untargeted analytes. There has been only a low number of publications describing the use of other MS-types, a fact related to slow spectral production rates. The requirement for high-speed MS systems is related to the
very fast second-dimension separations. The present investigation is focused on the exploitation of a novel high-speed triple quadrupole (QqQ) mass spectrometer, in flow-modulated GC×GC applications. The QqQ MS is capable of operation in the simultaneous full-scan/MRM (multiple reaction monitoring) mode, under the high-speed spectral production conditions required for GC×GC identification and quantification. It will be shown that, in the same GC×GC-QqQ MS
analysis, both full-scan spectra relative to untargeted compounds, and MS-MS spectra relative
to targeted ones, can be attained. Obviously, the use of the MRM mode enables a great increase
both in sensitivity and selectivity. A GC×GC-QqQ MS application on an essential oil, containing
contaminants at the sub-ppb level, will be illustrated and discussed
Flow-modulated Comprehensive 2D Gas Chromatography-Mass Spectrometry assisted by a novel data-processing software
No full textOver the last decade, several cryogenic modulators have been developed, and found application in the comprehensive two-dimensional gas chromatography (GC×GC) field. Although the effectiveness of such a modulation approach is not under discussion, it is also a rather expensive issue. Consequently, the concept and development of low-costing flow modulation methods is of high interest.
The present lecture is focused on the development and use of a highly flexible, chip-based flow modulator for comprehensive two-dimensional gas chromatography. The novel modulation system consists of a metallic disc (chip), with internal channels, located entirely within the GC oven; apart from the two dimensions, the disc is linked to an auxiliary pressure unit, and is characterized by an interchangeable sample loop, which simplifies the optimization step and maximizes the overall GC×GC performance. The valve part of the modulator is located outside the GC oven, and, hence, there are no temperature restrictions.
A series of flow-modulated GC×GC-MS applications will be shown, relative to a variety of complex real-world samples. The data processing step was simplified by use of a novel, user-friendly comprehensive chromatography software
