Fundamentals of Sample Preparation for Environmental Analysis - Fundamentals of Environmental Sampling and Analysis - page 173

Step 1
Figure 7.7 Five steps of solid phase extraction: (a) Select the proper SPE tube or disk from various
commercially available SPEs, (b) Condition the SPE tube or disk, (c) Add the sample; (d) Wash the
packing; (e) Elute the compounds of interest (Courtesy of Supelco)

Step 2 Step 3 Step 4 Step 5

Cartridge

Vacuum

Vacuum
pump

Figure 7.8 Vacuum manifold
for solid phase extraction (SPE) of
multiple cartridge units

Collection
Tube

(c) Automation is possible for SPE, resulting in reduced analytical cost, time,
and labor.

7.3.3 Solid Phase Microextraction

Solid phase microextraction (SPME) is an ''extraction'' technique but, in fact, it is
based on a solvent-free sorption-desorption process. SPME typically is a fused silica
fiber coated with a solid adsorbent or an immobilized polymer, or a combination of
the two. The fiber has a typical dimension of 1 cm110

m, which is normally
bonded to a stainless steel plunger and installed in a holder that looks like a
modified microliter syringe. The fiber is introduced into the liquid sample or
headspace, and organic analytes adsorb in the phase and establish equilibrium.
The analytes are then desorbed from the fiber to a capillary GC column in the
heated injection port. SPME has also been coupled with HPLC, expanding the
application to nonvolatile compounds such as surfactants and pharmaceutical
chemicals. SPME is relatively a new sample preparation technique, but its
applications have been promising for the analysis of SVOCs as well as VOCs. The

m