محمد رضا حاج محمدی

A novel design of hollow fiber liquid phase microextraction containing multi-walled carbon nanotubes as a solid sorbent, which is immobilized in the pore and lumen of hollow fiber via sol-gel technique was developed for pre-concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples. Proposed method utilized both solid and liquid phase microextraction mediums. Affecting parameters on the extraction of polycyclic aromatic hydrocarbons were optimized in two successive steps as follows. Firstly, a methodology based on a quarter factorial design was used to choose the significant variables. Then, these significant factors were optimized utilizing central composite design. Under the optimized condition (extraction time= 25 min, amount of multi-walled carbon nanotubes =78mg, sample volume=8 ml, and desorption time=5 min), the calibration curves showed high linearity (R2=0.99) in the range of 0.01-500 ng/ml and the limit of detections were in the range of 0.007-1.47 ng/ml. The obtained extraction recoveries for 10 ng/ml of polycyclic aromatic hydrocarbons standard solution were in the range of 85-92%. Replicating the experiment in above condition for five times, gave the relative standard deviations lower than 6%. Finally, the method was successfully applied for pre-concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples.