Solid-phase microextraction automated method

An automated in-tube solid-phase microextraction HPLC method for NNK and several metabolites have been developed by Mullett et al. ° In-tube SPME is an on-line extraction technique where analytes are extracted and concentrated from the sample directly into a coated capillary by repeated draw-eject steps. A tailor-made polypyrrole-coated capillary was used to evaluate their extraction efficiencies for NNK and several metabolites in cell cultures. This automated extraction and analysis method simplified the determination of the tobacco-specific A-nitrosamines, requiring a total sample analysis time of only 30 min. 

Source Identified among 139 volatile compounds identified in cantaloupe Cucumis melo wur. reticulates cv. Sol Real) using an automated rapid headspace solid phase microextraction method (Beaulieu and Grimm, 2001). 

Identified as one of 140 volatile constituents in used soybean oils collected from a processing plant that fried various beef, chicken, and veal products (Takeoka et al., 1996). Also identified among 139 volatile compounds identified in cantaloupe Cucumis melo vslV. reticulates cm. Sol Real) using an automated rapid headspace solid phase microextraction method (Beaulieu and Grimm, 2001). 

The most sensitive method for CVAA has recently been reported by Wooten et al. (39) using solid-phase microextraction to concentrate the derivatized analyte. Urine, with added ammonium acetate buffer and PhAsO as an internal standard, was derivatized directly with 1,3-propanedithiol and the derivative concentrated on a poly(dimethylsiloxane) (PDMS) solid-phase microextraction (SPME) fiber. Analysis was by automated GC/MS using SIM of the isotopic MH+ ions. An impressive detection limit of 7.4pg/ml was reported, using a benchtop GC/MS system. The method was validated using spiked human urine. 

These semi-preparative methods are useful where identification is required but for quantitative and comparative analytical purposes much more rapid sampling techniques, such as automated headspace and solid phase microextraction (SPME), may be preferred. Both of these techniques give similar results for most volatiles. In the former, the vapour above a heated sample is removed by a syringe or gas flushing and injected onto a GC column, either directly or after trapping on a suitable absorbent and thermal desorption. In SPME, the vapour is absorbed on to a suitable bonded medium on a special needle and then injected into the gas chromatogram. 

Before any sample can be subjected to chromatography, some type of sample preparation is required, which can be as simple as filtration or an involved solid-phase extraction protocol. Sample preparation is that activity or those activities necessary to prepare a sample for analysis. The ultimate goal of sample preparation is to provide the component of interest in solution, free from interferences and at a concentration appropriate for detection. This entry will briefly discuss seven topic areas included in sample preparation standard methods, solid-phase extraction (SPE), matrix solid-phase dispersion (MSPD), solid-phase microextraction (SPME), microdialysis, ultraliltration (UF), and automated systems. 

Analytical methods for the detection of fipronil residues have been developed for such matrices as honeybees (10) using solid phase dispersion and gas chromatography (GC), and water and soil samples using solid phase microextraction (SPME) and GC-mass spectrometry (GC-MS) (II). Pressurized fluid extraction (PFE) is an extraction technique gaining in popularity due to its ease of use and automated state, its reduction in organic solvent consumption, and time saving. It is a prime extraction method for solid or semi solid sanq)les (12). The objective of this work was to develop a quick and reliable method for the extraction and analysis of fipronil and its main three metabolites in the Hawaiian soil. The method was applied to soil and cotton gauze samples collected on the island of Maui, Hawaii, in March 2002 after a residential spray of fipronil. 

Several sample pre-treatment methods have been proposed, aiming both at sample clean-up to reduce interferences and pre-concentration of which some have been duly validated and integrated in standardised analysis procedures and automated devices (Pinheiro et al. 2004). Those pre-treatments will increase the accuracy and sensitivity of the detection and lead to faster analyses and better reproducibility. Besides, these procedures may attain minimal sample volume requirements and avoid of analyte losses through evaporation. Liquid-phase extraction, LPE, (Alaejos et al. 2008 Sun et al. 2012b) solid-phase extraction, SPE, (Alaejos et al. 2008 Martinez et al. 2000), solid-phase microextraction, SPME, (Alaejos et al. 2008 DeBruin et al. 1999 Sharma et al. 2011), liquid-liquid-liquid microextraction. 

Some of the newer procedures use the same basic principles as the older extraction methods but provide fast and easy-to-use options and generally consume less organic solvent. For the most part, they have higher initial purchase price than the traditional methods. Examples include supercritical fluid extraction, accelerated solvent extraction, and automated solid-phase extraction and microextraction. Modular systems are now readily available that automate these proce-... 

---