Hian
Kee Lee
Department
of Chemistry
National University of Singapore
The demand for easy-to-handle, fast,
and efficient sample preparation methods is very high for many analytical
applications. In particular, there is a necessity for the efficient extraction
of ultratrace quantities of persistent organic pollutants (POPs) in complex
environmental samples; this is a challenging task. In response to the need
for a simple, cost-effective and rapid means to process various aqueous samples
in relation to POP analysis, we have been developing novel sample preparation
techniques. An example of this is polymer-coated hollow fiber microextraction
(PC-HFME), in which an adsorbent is coated onto polypropylene hollow fibre
membrane, and used for extraction of POPs from aqueous samples. We have also developed what we term functionalized
carbon nanotube-supported micro-solid phase extraction (µ-SPE) in which small amounts
of multiwalled carbon nanotubes are used as adsorbents. Both techniques exhibit
good analytical sensitivity and low detection limits (in the parts-per-trillion
range) for POPs in seawater and bovine milk samples, respectively. The potential
for field (on-site) sample preparation of POPs in seawater samples by PC-HFME
is being investigated, and compared to classical methods which are time-consuming
and involves multiple steps and dedicated apparatus, is very promising. µ-SPE gives very high sample enrichment and clean-up (without any pretreatment)
compared to solid-phase microextraction, an established commercially available
procedure. In addition to POP extraction, this paper also describes the preliminary
results of the extraction of phenols by an organic solvent-free liquid-phase
microextraction approach.