The urinary metabolic profile of diethylene glycol methyl ether and triethylene glycol methyl ether in Sprague-Dawley rats and the role of the metabolite methoxyacetic acid in their toxicity.

Ethylene glycol ethers are a well-known series of solvents and hydraulic fluids derived from the reaction of ethylene oxide and monoalcohols. Use of methanol as the alcohol results in a series of mono, di and triethylene glycol methyl ethers. The first in the series, monoethylene glycol methyl ether (EGME or 2-methoxyethanol) is well characterised and metabolises in vivo to methoxyacetic acid (MAA), a known reproductive toxicant.

Metabolic Profiling Reveals Differences in Plasma Concentrations of Arabinose and Xylose after Consumption of Fiber-Rich Pasta and Wheat Bread with Differential Rates of Systemic Appearance of Exogenous Glucose in Healthy Men.

Background: The consumption of products rich in cereal fiber and with a low glycemic index is implicated in a lower risk of metabolic diseases. Previously, we showed that the consumption of fiber-rich pasta compared with bread resulted in a lower rate of appearance of exogenous glucose and a lower glucose clearance rate quantified with a dual-isotope technique, which was in accordance with a lower insulin and glucose-dependent insulinotropic polypeptide response.

Objective: To gain more insight into the acute metabolic consequences of the consumption of products resulting in differential glucose kinetics, postprandial metabolic profiles were determined.

A novel safety assessment strategy applied to non-selective extracts.

A main challenge in food safety research is to demonstrate that processing of foodstuffs does not lead to the formation of substances for which the safety upon consumption might be questioned. This is especially so since food is a complex matrix in which the analytical detection of substances, and consequent risk assessment thereof, is difficult to determine. Here, a pragmatic novel safety assessment strategy is applied to the production of non-selective extracts (NSEs), used for different purposes in food such as for colouring purposes, which are complex food mixtures prepared from reference juices.

Comparative toxicokinetics of low-viscosity mineral oil in Fischer 344 rats, Sprague-Dawley rats, and humans--implications for an Acceptable Daily Intake (ADI).

Oral repeated-dose studies with low-viscosity mineral oils showed distinct species and strain differences, which are hypothesized to be due to differences in bioavailability, with Fischer 344 rats being more susceptible than Sprague-Dawley rats or dogs. Sensitive analytical methodology was developed for accurate measurement of low levels of mineral hydrocarbons and applied in single-dose toxicokinetics studies in rats and humans. Fischer 344 rats showed a 4-fold higher AUC(0-∞) and consistently higher blood and liver concentrations were found than Sprague-Dawley rats.

Peak clustering in two-dimensional gas chromatography with mass spectrometric detection based on theoretical calculation of two-dimensional peak shapes: the 2DAid approach.

A method is presented to facilitate the non-target analysis of data obtained in temperature-programmed comprehensive two-dimensional (2D) gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-ToF-MS). One main difficulty of GC×GC data analysis is that each peak is usually modulated several times and therefore appears as a series of peaks (or peaklets) in the one-dimensionally recorded data. The proposed method, 2DAid, uses basic chromatographic laws to calculate the theoretical shape of a 2D peak (a cluster of peaklets originating from the same analyte) in order to define the area in which the peaklets of each individual compound can be expected to show up.

Higher mass loadability in comprehensive two-dimensional gas chromatography-mass spectrometry for improved analytical performance in metabolomics analysis.

A major challenge in metabolomics analysis is the accurate quantification of metabolites in the presence of (extremely) high abundant metabolites. Quantification of metabolites at low concentrations can be complicated by co-elution and/or peak distortion when these metabolites elute close to high abundant metabolites. To increase the separation efficiency a comprehensive two-dimensional gas chromatographic-mass spectrometric method (GC x GC-MS) was set up, in which a polar first dimension column and an apolar second dimension column were used to maximize the peak capacity.

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection for the trace analysis of flavour compounds in food.

The practicability and potential of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC-TOF-MS) for the analysis of complex flavour mixtures in food were studied. With the determination of key flavour targets in dairy samples as an example, it was demonstrated that GC x GC dramatically improves the separation. As a consequence, identification and, more importantly, quantification down to the ng/g level can be performed more reliably: background interferences largely disappear.

Comprehensive two-dimensional gas chromatography with atomic emission detection and correlation with mass spectrometric detection: principles and application in petrochemical analysis.

Comprehensive gas chromatography (GC x GC) has been combined with atomic emission detection (AED) to enable element-selective detection. Under optimised experimental conditions, the requirement of minimum five data points across a peak can be obtained even for analytes eluting early from the second-dimension column. Simple manipulation of the results allows the combined presentation of up to four sets of elemental data in one two-dimensional plot.

Responses in sediment bioassays used in the Netherlands: can observed toxicity be explained by routinely monitored priority pollutants?

In order to identify the cause of toxicity in sediments and suspended matter, a large number of samples with different degrees of contamination was taken at various locations in The Netherlands. Standard acute bioassays were carried out with the bacterium Vibrio fischeri, the rotifer Brachionus calyciflorus and the anostracan Thamnocephalus platyurus. Chronic standard tests were performed using the water flea Daphnia magna and larvae of the midge Chironomus riparius.

Unravelling the composition of very complex samples by comprehensive gas chromatography coupled to time-of-flight mass spectrometry. Cigarette smoke.

The potential and current limitations of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC-TOF-MS) for the analysis of very complex samples were studied with the separation of cigarette smoke as an example. Because of the large number of peaks in such a GC x GC chromatogram it was not possible to perform manual data processing. Instead, the GC-TOF-MS software was used to perform peak finding, deconvolution and library search in an automated fashion; this resulted in a peak table containing some 30000 peaks.

Use of semi-permeable membrane devices and solid-phase extraction for the wide-range screening of microcontaminants in surface water by GC-AED/MS.

An automated GC-MS-based screening method was developed for over 400 industrial, agrochemical and household chemicals. Extracted ion chromatograms were used and the method was aimed at creating a minimum number of false positives. The compound polarity range usually associated with solid-phase extraction was extended to include very apolar, bioaccumulative, compounds by using the complementary semi-permeable membrane device technique.