Solid-phase extraction advances

This chapter will review recent advances in mass spectrometry, liquid chromatography, and sample preparation techniques that aim at achieving high throughput. In particular, online solid phase extraction and multiplexed HPLC front ends for quantitative bioanalysis will be discussed in detail. 

The most important solid-phase separation materials for column-based separations in modern radioanalytical chemistry are extraction chromatographic materials, and these have been particularly important in automated radioanalytical chemistry. Solid-phase extraction materials based on the covalent attachment of ligands to solid supports also exist, and they have found application in large-scale separation processes for waste or effluent treatment.22 25 They have been commercialized as Analig or SuperLig materials by IBC Advanced Technologies (American Fork, UT). However, they are less well characterized or used for small-column analytical separations. 

After several decades of research, fundamental aspects of the chemical composition and structure of marine organic matter remain elusive. Advances in the chemical characterization of marine organic matter are, in large part, dependent on the development of quantitative methods for its concentration and isolation from seawater. Each of the major methods currently used for the isolation of marine DOM recovers around one-third of the DOM in seawater (solid-phase extractions, using XAD resins or C18 adsorbents, and ultrafiltration). A coupled reverse osmosis-electrodi-alysis method has recently been used to recover an average of 75% 12% of marine DOM from 16 seawater samples however, the method has emerged too recently to have been well tested at this time. 

Thurman, E.M., and K. Snavely (2000). Advances in solid-phase extraction disks for environmental chemistry. Trends Anal. Chem., 19 18-26. 

Another advanced and novel sample preparation technique is online solid phase extraction (online SPE). Although the extraction mechanism is as the same as traditional offline SPE, online SPE offers several advantages. Because sample preparation is carried out during analysis, it eliminates the time needed for sample preparation thus increases throughput significantly. Additionally, because the entire sample is eluted to the LC-MS/MS system, it may increase assay sensitivity. Finally, because there is no manual extraction involved, it may reduce human error, potential contamination, and inconsistent recovery. 

Advances made in solid phase extraction (SPE) and in development of resin-based scavengers have increased the versatility of chemistries implemented for synthesis of... 

Blevins, D.D. Hall, D.O. Recent advances in disk format solid-phase extraction. LC GC 1998, 13 (5), S16-S21. 

Molinelli, A. Weiss, R. Mizaikoff, B., Advanced solid phase extraction using molecularly imprinted polymers for the determination of quercetin in red wine, J. Agric. Food Chem. 

Hearne, G. M. and Hall, D. O. 1993. Advances in solid-phase extraction technology. Am. Lab., January, 28H-28M. 

Most nitroimidazole methods also incorporate further clean-up steps such as solid phase extraction (SPE). Some common phases used include Oasis Oasis MCX, Chromabond XTR, SCX, Bakerbond Silica, and MIP-SPE (molecular imprinted polymer). In addition, most methods incorporate a solvent washing step with solvents such as hexane prior to instrumental analysis for removal of non-polar material. More recent work bypassed extensive clean-up techniques such as SPE as it was felt that recent advances in MS/MS technologies and... 

Christie, W.W. Solid-phase extraction columns in the analysis of lipids. In Advances in Lipid Methodology, Volume 1 Christie, W.W., Ed. The Oily Press Arly, Scotland, 1992 1-17. 

When a spectral plot is not available, the absorbance ratio method is a satisfactory method for characterizing a real sample, using both spectrophotometric and HPLC assays. In addition, better performance needs to be achieved in carrying out advanced experiments, such as solid-phase extraction and other purification techniques coupled with HPLC quantification, in order to improve the separation properties. " ... 

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