Solid-phase extraction factors affecting

As a general rule, APCI is less likely to demonstrate matrix effects and ESI is more likely to be affected by matrix effects. Sample clean-up is another important factor—protein precipitation is more likely to result in matrix effects than is solid phase extraction. Matrix effects may be caused by sample constituents that are not parts of the biological matrix. Mei et al.126 129 showed that certain brands of sample tube containers can produce matrix effects. They also demonstrated that Li-heparin, a common anticoagulant for plasma samples, can produce significant matrix effects... 

Raisglid, M., Burke, M. E, and Van Horne, K. C. 1993. Factors affecting the reliability of solid-phase extraction for environmental analysis. International Symposium on Laboratory Automation and Robotics, Amsterdam, pp. 1-7. 

Solid-phase microextraction (SPME) was introduced in the early 1990s by Arthur and Pawliszyn. SPME is a simple solvent-free sample preparation method for GC and LC. The extraction is based on the partitioning of the analyte between the organic phase on the fused silica fiber and the matrix. Many factors such as pH, temperature, salt concentration, and stirring affect the equilibrium constant and the equihbration time. Fiber lifetime is a significant issue. SPME fiber is quite sensitive to complex matrix such as... 

The diffusion coefficient (or diffiisivity) and viscosity represent transport properties which affect rates of mass transfer. In general, these properties are at least an order of magnitude higher and lower, respectively, compared with liquid solvents. This means that the diffusion of a species through an SCF medium will occur at a faster rate than that obtained in a liquid solvent, which implies that a solid will dissolve more rapidly in an SCF. In addition, an SCF will be more efficient at penetrating a microporous solid structure. However, this does not necessarily mean that mass transfer limitations will always be absent in an SCF process. For example, in the extraction of a solute from a liquid to an SCF phase, the resistance to diffusion in the liquid phase will probably control the overall rate of mass transfer. Stirring will therefore continue to be an important factor in such systems. 

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