Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
38, Number 12, December 2000, pp. 528-534
Solid-Phase
Microextraction and Headspace Solid-Phase Microextraction for the Determination
of High Molecular-Weight Polycyclic Aromatic Hydrocarbons in Water and Soil
Samples
Ruey-an
Doong[1], Sue-min Chang[1], and Yuh-chang Sun[2]
[1]Department of Atomic Science and
[2]Nuclear Science and Technology Development Center, National Tsing Hua University,
Hsinchu,
30013, Taiwan
The
feasibility of direct-immersion (DI) solid-phase microextraction (SPME) and
headspace (HS) SPME for the determination of high-ring polycyclic aromatic hydrocarbons
(PAHs) (4- to 6-ring PAHs) in water and soil samples is studied. Three SPME
fibers—100- and 30-µm polydimethylsiloxane (PDMS) and 85-µm
polyacrylate (PA) fibers—are compared for the effective extraction of PAHs.
Parameters affecting the sorption of PAHs into the fiber such as sampling time,
sampling volume, and temperature are also evaluated. The extracted amounts of
high-ring PAHs decrease with the decreasing of film thickness, and the 100-µm
PDMS has the highest extraction efficiency than 85-µm PA and 30-µm
PDMS fibers. Also, the extraction efficiency decreases with the increasing molecular
weights of PAHs. Of the 10 high-ring PAHs, only fluoranthene and pyrene can
reach equilibrium within 120 min at 25°C for DI-SPME in a water sample.
Increasing the temperature to 60°C can increase the sensitivity of PAHs
and shorten the equilibrium time. A 0.7- to 25-fold increase in peak area is
obtained for DI-SPME when the working temperature is increased to 60°C.
For HS-SPME, the extraction efficiency of PAHs decrease when the headspace volume
of the sampling system increases. All high-ring PAHs can be detected in a water
sample by increasing the temperature to 80°C. However, only 4- and 5-ring
PAHs can be quantitated in a CRM soil sample when HS-SPME is used. The addition
of a surfactant with high hydrophilic property can effectively enhance the sensitivity
of high-ring PAHs. HS-SPME as well as DI-SPME with 100-µm PDMS or 85-µm
PA fibers are shown to be suitable methods for analyzing high-ring PAHs in a
water sample; however, this technique can only apply in a soil sample for PAHs
having up to 5 rings.
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