تسجيل الدخول

تسجيل

Solid Phase Extraction

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  362

2026-08-11

25

Solid Phase Extraction

To overcome the limitations of liquid phase extraction and increase sensitivity, solid phase extraction of drugs has become popular in recent years. In solid phase extraction a small column or coated wire is used to extract the drug out of the urine or blood. The blood or urine is poured through a special solid matrix that selectively removes the drug. The matrix is then washed or eluted to strip the drug off for further analysis. A recent refinement of solid phase extraction is solid phase microextraction (SPME). Here a specially coated wire, strip, or fiber is inserted into the fluid that contains the drug or drugs. The drugs are selectively adsorbed onto the wire, which is then removed. The drug can then be eluted for further analysis. SPME is capable of capturing and measuring very small amounts of drug, so it is ideal for situations where there is limited sample available. Even if there are many substances dissolved in the liquid, there are coatings that can be used to adsorb a particular type of substance. Figure 1 shows how the SPME process works.

FIGURE 1 Solid phase microextraction (SPME). The coated wire on the end is immersed into the blood or urine sample that contains the drugs of interest. The drugs adsorb onto the surface of the wire. The wire can then be eluted with a solvent or introduced directly into the inlet of a gas chromatograph where the heat will remove the drugs and they will then be swept into the gas chromatograph.