An analytical technique is described which combines solvent extraction with gas chromatographic (GC) analysis in a simple and inexpensive apparatus involving very little solvent consumption. A small drop (8 μL) of a water-immiscible organic solvent, containing an internal standard, is located at the end of a Teflon rod which is immersed in a stirred aqueous sample solution. After the solution has been stirred for a prescribed period of time, the probe is withdrawn from the aqueous solution, and the organic phase is sampled with a microsyringe and injected into the GC for quantification. The observed rate of solvent extraction is in good agreement with a convective−diffusive kinetic model. Analytically, the relative standard deviation of the method is 1.7% for a 5.00-min extraction of the analyte 4-methylacetophenone into n-octane.

Solvent microextraction into a single drop.

Solid-phase extraction: method development, sorbents, and coupling with liquid chromatography

Solid phase extraction of trace elements

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

Membrane approach to solid-phase extractions

Solid-phase extraction of phenols using membranes loaded with modified polymeric resins

A solid phase extraction or chromatographic medium comprises a porous nonwoven fibrous matrix comprising at least one of polytetrafluoroethylene and blown microfibers, and sorptive or reactive hydrophobic siliceous molecular sieve particulates enmashed in said matrix, the ratio of molecular sieves to matrix being in the range of 40:1 to 1:40.

Composite membranes for solid phase extractions and reactions

A sheet article for solid phase extraction or solid phase reaction comprises at least one sorptive polymer pulp, and optionally at least one of sorptive and reactive particulate The article can be used in a method of separating an analyte from a fluid comprising the step of passing a fluid comprising an analyte through a sheet article comprising poly(p- or m-phenylenephthalamide) pulp, the pulp optionally having incorporated therein solid phase particulates, the sheet article being capable of isolating the analyte from the fluid

Sheet materials for solid phase extractions and solid phase reactions

Composite articles are useful for separating mercury from fluids. The composite articles can be porous supports comprising an inert substrate having immobilized thereon finely divided gold optionally in combination with a tin salt coating. The porous support can be a particulate or porous fibrous web. Alternatively, the composite articles can comprise a porous fibrous membrane having enmeshed therein the aforementioned porous supports which can be in particulate or fibrous forms. The method for separating elemental, ionic, or organic mercury in fluids comprises the steps of contacting and passing a fluid containing mercury through a support comprising a porous, high surface area, inert substrate on which is immobilized finely divided elemental gold at a controlled rate for a time sufficient for the mercury to sorb to the elemental gold and to provide an immobilized gold-mercury amalgam on the support. If a tin salt also is immobilized on the inert substrate, mercury-tin salt can also be formed. In a further, and optional, step, elemental mercury can be removed from the support and optionally can be quantified.

Donald F. Hagen

Papers

Membrane approach to solid-phase extractions

Solid-phase extraction of phenols using membranes loaded with modified polymeric resins

Composite membranes for solid phase extractions and reactions

Sheet materials for solid phase extractions and solid phase reactions

Composite articles for separating mercury from fluids