April 7, 2011 – FARS News Agency — Iranian researchers at Mashhad’s Ferdowsi University improved the quality of microextraction by incorporating carbon nanotubes (CNTs).
"We studied trace measurements of environmental samples by gas-liquid chromatography method and applying a new pre-concentration method," Dr. Sarafraz Yazdi, professor at Ferdowsi University, told INIC.
Pre-concentration (extraction) methods demand high consumption of organic solvents, which are expensive and pollute the environment. Scientists have been working on microextraction methods that need no or little amounts of solvent since the 1990s. "One of the non-solvent methods is solid phase microextraction (SPME) in which some solid phase adsorbent (of micrograms) is placed on a capillary fiber of melted silica. This fiber is exposed to the sample and adsorbs it. Afterwards, desorption process takes place in measurement device," Yazdi said.
"In the present study, we placed different adsorbents on fiber through chemical bonding by means of sol-gel methods, which have many advantages over its initial formation. We deposited polyethylene glycol (PEG), a polar compound, on the fiber by sol-gel method. We also managed to introduce functionalized [multiwall carbon nanotubes] MWCNTs to PEG and deposited it on fiber through the aforementioned method. The presence of CNTs resulted in an increase in the effective adsorbent surface and performance of the method."
It is possible to use this method for pre-concentration and measurement of trace environmental samples without using toxic organic solvents.