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...North harrison road bellefonte pa usa telephone fax email supelco sial com sigma aldrich bulletin guide to solid phase extraction page introduction types reversed packings normal ion exchange adsorption spe theory how compounds are retained by the sorbent secondary interactions role of ph in use selecting proper scheme five step method development process sample pretreatment options liquid samples hardware and accessories for processing is an increasingly useful preparation technique with many problems associated can be prevented such as incomplete separations less than quantitative recoveries expensive breakable specialty glassware disposal large quantities organic solvents more efficient yields quantita tive extractions that easy perform rapid automated solvent lab time reduced used most often prepare extract semivolatile or nonvolatile analytes but also solids pre extracted into products excellent concentration cleanup they available a wide variety chemistries adsorbents sizes suita...