Solid-phase extraction is a technique used to purify and/or concentrate certain compounds in a liquid mixture prior to chromatographic analysis. Compounds in the aqueous mixture are separated based on physical and chemical properties that give them more or less affinity for a solid phase. The technique can be used successfully for urine, blood, water, beverages, soil, and animal tissue. During the process, one part of the sample binds to the stationary phase while the other passes through. In some cases, the compound of interest has a low affinity for the solid phase and passes through while other compounds are retained. In those cases, the liquid is collected for analysis. In other cases, the compound of interest has a high affinity for the solid phase, while other compounds pass through. In that case, the liquid that flows through is discarded and a different eluent is used to elute the compound from the stationary phase. It is then collected for further analysis. In either case, the result is a solution enriched for the analyte of interest, making that analyte stand out from background noise on a chromatogram.
Automated solid-phase extraction is ideal for laboratories looking to automate large-volume water extractions. Typical applications include PAH, PCB, PCDD, PCDF, PFAS, pesticides, herbicides, flame retardants, semivolatiles, nitrosamines, and steroids. Applications for the Thermo Scientific Dionex AutoTrace 280 SPE system include many US EPA methods and a variety of other SPE sample preparation cleanup methods including: