Solid phase extraction, usage

Significant improvements in the isolation of pharmaceutical compounds from plasma, serum and urine, have been achieved using ultra low mass sorbent bed and thin disk solid-phase extraction (SPE) material. The use of low sorbent masses or disk SPE material has allowed a significant reduction in solvent usage and extraction times. Several SPE RP-HPLC methods have been developed using these materials, including... 

B. A. Bildenmeyer, Guidelines for proper usage of solid-phase extraction devices, LC, 2 578 (1984). 

Matrix solid-phase dispersion (MSPD) is an SPE variant where samples are ground and mixed with a support. In the initial application, samples were placed in a disposable column previously packed with Florisil, which trapped the fat from the sample and allowed the compounds of interest to be eluted. This has successfully been applied to the determination of lipophilic pesticides from both fatty and non-fatty matrixes. Recently, an orthogonal technique, dispersive solid-phase extraction, for the isolation and analysis of a variety of pesticides on numerous food matrixes has been introduced. The technique is called QuEChERS, which stands for quick, easy, cheap, effective, rugged, and safe. The technique offers advantages in time and solvent usage since it uses approximately 10 ml of solvent per sample when compared to the potentially hundreds of milliliters of solvent used for more standard extraction and isolation protocols. It uses a combination of MgS04 and primary secondary amine (PSA) sorbent not only to remove water and non-target compounds, but also isolate the compounds of interest. 

Miniaturisation of scientific instruments, following on from size reduction of electronic devices, has recently been hyped up in analytical chemistry (Tables 10.19 and 10.20). Typical examples of miniaturisation in sample preparation techniques are micro liquid-liquid extraction (in-vial extraction), ambient static headspace and disc cartridge SPE, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE). A main driving force for miniaturisation is the possibility to use MS detection. Also, standard laboratory instrumentation such as GC, HPLC [88] and MS is being miniaturised. Miniaturisation of the LC system is compulsory, because the pressure to decrease solvent usage continues. Quite obviously, compact detectors, such as ECD, LIF, UV (and preferably also MS), are welcome. 

Yang R, Xie W. Preparation and usage of a new solid phase micro-extraction membrane. Forensic Sci Int 2004 139 177-81. 

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