Analysis of the reaction products from micro-vial pyrolysis of the mixture glucose/proline and of a tobacco leaf extract:Search for Amadori intermediates.

Micro-vial pyrolysis (PyroVial) was used to study the production of compounds important for the aroma of heat-treated natural products such as tobacco. Firstly, a mixture of glucose and proline was pyrolyzed as model, as this sugar and amino acid are also abundant in tobacco leaf (Nicotiana tobacum L.).

Coupling gas chromatography and electronic nose detection for detailed cigarette smoke aroma characterization.

Aroma characterization of whole cigarette smoke samples using sensory panels or electronic nose (E-nose) devices is difficult due to the masking effect of major constituents and solvent used for the extraction step. On the other hand, GC in combination with olfactometry detection does not allow to study the delicate balance and synergetic effect of aroma solutes. To overcome these limitations a new instrumental set-up consisting of heart-cutting gas chromatography using a capillary flow technology based Deans switch and low thermal mass GC in combination with an electronic nose device is presented as an alternative to GC-olfactometry.

Increasing productivity for the analysis of trace contaminants in food by gas chromatography-mass spectrometry using automated liner exchange, backflushing and heart-cutting.

Laboratories focusing on residue analysis in food are continuously seeking to increase sample throughput by minimizing sample preparation. Generic sample extraction methods such as QuEChERS lack selectivity and consequently extracts are not free from non-volatile material that contaminates the analytical system. Co-extracted matrix constituents interfere with target analytes, even if highly sensitive and selective GC-MS/MS is used.

Heart-cutting two-dimensional gas chromatography in combination with isotope ratio mass spectrometry for the characterization of the wax fraction in plant material.

Gas chromatography coupled to isotope ratio mass spectrometry after on-line combustion (GC-C-IRMS) and high temperature conversion (GC-HTC-IRMS) is used for compound specific isotope ratio determination. This determination can only be performed successfully if the target solutes are fully resolved from other compounds. A new instrumental set-up consisting of heart-cutting two-dimensional GC based on capillary flow technology and a low thermal mass GC oven in combination with an isotope ratio mass spectrometer is presented.

Exploring the possibilities of cryogenic cooling in liquid chromatography for biological applications: a proof of principle.

The possibilities to use cryogenic cooling to trap components in liquid chromatography was investigated. In a first step, van 't Hoff plots were measured with a reversed-phase column using the temperature control unit of a conventional high performance liquid chromatography (HPLC) system to gain insight in the retention behavior of proteins at low temperatures. It was estimated that retention factors in the range of k = 10(4) could be achieved at T = -20 °C for lysozyme, indicating that temperature is a usable parameter to trap components in LC.

In-vial pyrolysis (PyroVial) with pre- and post-sample treatment combined with different chromatographic techniques.

A new generic pyrolysis unit (PyroVial) is presented. Pyrolysis is carried out in a 2 mL autosampler vial placed in a XYZ robot for automated pyrolysis as well as for pre- and post-pyrolysis treatment of the sample. Analysis of the volatiles is performed by headspace analysis while the semi- and non-volatiles are extracted from the pyrolysate with an organic solvent.

Gas chromatography of 209 polychlorinated biphenyl congeners on an extremely efficient nonselective capillary column.

The gas chromatographic-mass spectrometric (GC-MS) separation of all 209 polychlorinated biphenyl (PCB) congeners was studied on an extremely efficient 80 m x 0.1mm i.d.

Features of a micro-gas chromatograph equipped with enrichment device and microchip plasma emission detection (muPED) for air monitoring.

A field portable gas chromatograph (GC) was constructed allowing the enrichment of organic solutes from air samples on a miniaturized chemical trap and the subsequent gas chromatographic analysis on a resistively heated capillary column. The heart of the system is an integrated chip-based plasma emission detector (muPED). As a non-selective detector, the sensitivity is similar to that of a flame ionization detector (FID).

Chemotaxonomy of bacteria by comprehensive GC and GC-MS in electron impact and chemical ionisation mode.

The analysis of the cellular lipidic fraction of bacteria is described. After hydrolysis and methylation, the fatty acid methyl esters (FAMEs) are determined by 1-D GC using the Sherlock MIDI bacteria identification system, by comprehensive GC (GC x GC) and by GC-MS in electron impact (EI) and positive chemical ionisation (PCI) mode. With GC x GC, the enhanced selectivity and group type separation provides a more complete elucidation of the fatty acids in microorganisms.

Comprehensive two-dimensional liquid chromatography applying two parallel columns in the second dimension.

The design of a new interface for comprehensive two-dimensional liquid chromatography (LC x LC) is described. To the conventionally used LC x LC system with the loop-type interface consisting of a two-position/ten-port switching valve equipped with two loops, an extra two-position/ten-port switching valve, a detector, a pump and a second column placed in parallel with the column in the second dimension, are added. The features of the interface are that the separation space in the second dimension is significantly enlarged and that the number of fractions transferred from the first to the second dimension can be increased, reducing the risk to lose resolution of the primary dimension.

Optimization of a multi-residue screening method for the determination of 85 pesticides in selected food matrices by stir bar sorptive extraction and thermal desorption GC-MS.

A multi-residue method to determine 85 pesticides, including organochlorine pesticides, carbamates, organophosphorus pesticides, and pyrethroids, in vegetables, fruit, and green tea, has been developed. The method is based on stir bar sorptive extraction (SBSE) coupled to thermal desorption (TD) and retention time locked (RTL) GC-MS operating in the scan mode. Samples are extracted with methanol and diluted with water prior to SBSE.

Kinetics of orally administered di(2-ethylhexyl) phthalate and its metabolite, mono(2-ethylhexyl) phthalate, in male pigs.

Di(2-ethylhexyl) phthalate (DEHP) is used as a plastic softener in the polymer industry and is widespread in medical devices. DEHP has been incriminated as an endocrine-disrupting chemical, and the effects of DEHP in various species have included disturbances in the reproductive system. The effects of the chemical have varied, depending upon exposure routes and species.

Multi-residue screening of pesticides in vegetables, fruits and baby food by stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry.

The performance of stir bar sorptive extraction (SBSE) for the enrichment of pesticides from vegetables, fruits and baby food samples is discussed. After extraction with methanol, an aliquot is diluted with water and SBSE is performed for 60 min. By applying a new thermal desorption unit (TDU), fully automated and unattended desorption of 98 stir bars is feasible, making SBSE very cost-effective.