Capillary extraction (CEx) is used to study the solventless in-tube extraction of naphthalene, acenaphthene, phenanthrene, fluoranthene, chrysene, benzo(a)pyrene and coronene in aqueous samples prepared by analyte spiking into clean waters or, as an alternative, by using the generator–column method of sample preparation. Analysis of laden extractors is conveniently performed by high-resolution gas chromatography (GC), with a flame-ionization detector (FID). Extraction set-ups and main extraction variables are investigated from a practical point of view. For 2- to 4-ring polycyclic aromatic hydrocarbons (PAHs), equilibrium times are within a few minutes, analytical sensitivity is in the parts-per-billion (ppb) range and reproducibility is better than 10% relative standard deviation (RSD) (n = 6). Coronene behaviour is unique and presumably determined by extreme hydrophobicity and thus very negligible aqueous solubility: in-tube extraction of coronene seems possible only if starting from..
The Column
Gas chromatography-mass spectrometry using a single-quadrupole instrument is the workhorse technique of the environmental lab. It normally falls short for applications that require high mass accuracy. It is shown here that with proper calibration techniques, this technique can indeed readily obtain high mass accuracies to within a few millidaltons and become a powerful tool for unknown compound identification.
LCGC Asia Pacific
Heidi Grecsek, PerkinElmer Life and Analytical Sciences
LCGC North America
Guest authors Luke Chimuka and Ewa Cukrowska provide an in-depth look at the verious approaches to passive sampling, weighing the merits and challenges for each type.
LCGC Asia Pacific
William Goodman and Heidi Grecsek, PerkinElmer Life and Analytical Sciences
LCGC North America
A method for the identification of key volatile organic compound (VOC) markers associated with infection by Neisseria meningitidis bacteria by gas chromatography–mass spectrometry (GC–MS) was developed. Headspace samples of bacterial VOCs were trapped on triple-sorbent bed tubes and then thermally desorbed into a laboratory GC–MS system for separation. Identification was carried out by comparison of GC retention time and electron ionization mass spectra to the National Institute of Standards and Technology (NIST) database. Further confirmation was obtained by GC–MS of known standard chemicals. A total of 75 VOCs were detected, five of which can be considered key VOC markers for Neisseria meningitidis. These peaks were identified as 1,2-dimethylcyclopropane, 2-methylpropanal, methacrolein, N-2-dimethyl-1-propanamine, and 3-methylbutanal by the NIST database.
LCGC Europe
Direct coupling of SFE with GC has advantages over the off-line alternative.
LCGC North America
As environmental legislation becomes more stringent, the need to deliver quantitative results in shorter times and greater volumes is necessary for routine environmental analysis. Most of the high-throughput screening methods used to analyze pharmaceutical compounds are, however, useless for environmental monitoring. This is because these methods primarily aim to retrieve as much information from a single sample using the broadest range of techniques. The chromatographic separation process is considered to be the bottleneck in the process. This is not the situation for environmental procedures, in which the bottleneck is the sample preparation step and is usually very tedious and time-consuming.
LCGC Europe
In this article, the authors look at ways to increase sample throughput for routine environmental analysis. Several strategies aimed at enhancing laboratory productivity are highlighted and illustrated with from-the-floor applications.
LCGC North America
The authors propose the use of supersaturated experimental designs for composite sampling and demonstrate their efficiency and economy in the environmental screening of pesticide residues.
LCGC North America
New miniaturized liquid-membrane extraction designs are especially suited for speciation studies of metal ions in small amounts of biological fluids.
LCGC North America
The authors evaluted the performance of a high-capacity anion-exchange column specifically designed for use with hydroxide eluents for fulfilling the requirements of EPA Method 300.0 Part A and compared the results with data generated with an anion-exchange column using carbonate eluents.
LCGC North America
This column describes the principles of stir-bar sorptive extraction and presents some typical applications.
LCGC North America
The authors discuss two environmental applications for accelerated solvent extraction.
The author configured a purge-and-trap GC-MS system that simultaneously improved chromatographic resolution and reduced analysis time.
