Headspace solid-phase microextraction is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the headspace above the sample. The volatilized organic analytes are extracted and concentrated in the coating and then transferred to the analytical instrument for desorption and analysis. This modification of the solid-phase microextraction method (SPME) shortens the time of extraction and facilitates the application of this method to analysis of solid samples. The detection limits of the headspace SPME technique are at ppt level when ion trap mass spectrometry is used as the detector and are very similar to that of the direct SPME technique

Headspace solid-phase microextraction

Two modes of liquid-phase microextraction (LPME) were developed for capillary gas chromatography. Both methodologies, i.e., static LPME and dynamic LPME, involve the use of very small amounts of organic solvent (<2 μL) in a conventional microsyringe. The performance of the two techniques is demonstrated in the determination of two chlorobenzenes extracted into a single drop of toluene by the use of a 10-μL syringe. Static LPME provided some enrichment (∼12-fold), good reproducibility (9.7%), and simplicity but suffered relatively long extraction time (15 min). Dynamic LPME provided higher (∼27-fold) enrichment within much shorter extraction time (∼3 min), and relatively poorer precision (12.8%), primarily due to repeated manual manipulation. Both methods allow the direct transfer of extracted analytes into a gas chromatograph.

Liquid-Phase Microextraction in a Single Drop of Organic Solvent by Using a Conventional Microsyringe

Solid-Phase Microextraction. A Solvent-Free Alternative for Sample Preparation

The accumulation of persistent organic pollutants by three passive sampling mediasemipermeable membrane devices (SPMDs), polyurethane foam (PUF) disks, and an organic-rich soilwas investigated. The media were exposed to contaminated indoor air over a period of 450 days, and concentrations in the air and in the media were monitored for individual polychlorinated biphenyl (PCB) congeners and polychlorinated naphthalene homologue groups. Uptake was initially linear and governed by the surface area of the sampler and the boundary layer air-side mass transfer coefficient (MTC). Mean values of the MTC were 0.13, 0.11, and 0.26 cm s-1 for SPMD, PUF, and soil, respectively. As the study progressed, equilibrium was established between ambient air and the passive sampling media for the lower molecular weight PCB congeners. This information was used to calculate passive sampler−air partition coefficients, KPSM-A. These were correlated to the octanol−air partition coefficient, and the resulting regressions were used ...

Characterization and comparison of three passive air samplers for persistent organic pollutants.

The solid-phase microextraction (SPME) technique involves exposing a fused silica fiber that has been coated with a stationary phase to and aqueous solution containing organic contaminants. The analytes partition into the stationary phase until an equilibrium has been reached, after which the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph

Automation and optimization of solid-phase microextraction

Solid-phase microextraction (SPME) was investigated as a solvent-free alternative method for the extraction and analysis of nonpolar semivolatile analytes. Analytes were extracted into a polymeric phase immobilized onto a fusedsilica fiber. The fiber was then inserted directly into the injector of a gas chromatograph, and the analytes were thermally desorbed. This new technique allows sampling directly from the source (lake, drinking fountain, etc.) and, therefore, eliminates the loss of analytes through adsorption onto container walls and saves transport costs

Rapid determination of polyaromatic hydrocarbons and polychlorinated biphenyls in water using solid-phase microextraction and GC/MS.

rn Solid-phase microextraction (SPME) is applied to the analysis of benzene, toluene, ethyl benzene, and xylenes in groundwater. The inexpensive SPME method reduced the sample preparation time by 3-7-fold when compared to purge and trap methods. The relative standard deviation ranged from 3 to 5% for the single-operator relative standard deviation using a methyl silicone fiber. Limits of detection of 1-3 ppb (w/v) were obtained when using a fiber coated with 56-pm methyl silicone film and FID detection. The linear range extended from 15 to 3000 ppb (w/v). Solvents have been completely removed from the sample preparation step.

Analysis of Substituted Benzene Compounds in Groundwater Using Solid-Phase Microextraction

Detection of substituted benzenes in water at the pg/ml level using solid-phase microextraction and gas chromatography-ion trap mass spectrometry.

Solid-phase microextraction for the direct analysis of water: theory and practice

A series of environmental samples, comprising fly ash, caustic wash water from regeneration of a petrochemical reforming catalyst, fish homogenates, soil, and pulp mill sludge, were analyzed for dioxin-like compounds by an assay involving competitive binding of a reference radioligand and an extract from the sample to mouse hepatic Ah receptor ; the results were compared with GC/MS. The bioassay generally gave higher TEQ values than GC/MS. Further analysis by GC/MS in most cases identified much of the additional Ah receptor-active material as coplanar PCBs and PAHs.

David W. Potter

Papers

Rapid determination of polyaromatic hydrocarbons and polychlorinated biphenyls in water using solid-phase microextraction and GC/MS.

Analysis of Substituted Benzene Compounds in Groundwater Using Solid-Phase Microextraction

Detection of substituted benzenes in water at the pg/ml level using solid-phase microextraction and gas chromatography-ion trap mass spectrometry.

Solid-phase microextraction for the direct analysis of water: theory and practice

Screening assay for dioxin-like compounds based on competitive binding to the murine hepatic Ah receptor. 2. Application to environmental samples.