Solid-phase microextraction of methadone by using a chitosan nanocomposite incorporated with Polyoxomolibdate nanocluster/Graphene oxide.

In the present study, we report on the simple sol-gel preparation of a nanocomposite composed of chitosan/ polyoxometalate /graphene oxide, and its application in the headspace solid-phase microextraction combined with the ion mobility spectrometry for the analysis of methadone in biological matrices. The developed nanocomposite was characterized through the infrared spectroscopy and thermogravimetric analyses. The ternary nanocomposite coating offers good mechanical and thermal stability and high extraction efficiency thanks to its large specific surface. A central composite statistical design was used to study the main variables affecting the extraction efficiency. Afterward, to study the relationship between different input and output variables as well as to identify the optimal operating conditions, response surface methodology was used, whereby a second-order polynomial equation was fit to the experimental data. The optimized extraction conditions were as follows: temperature, 70°C; extraction time, 15 min; and concentration of NaCl, 5%w/v. The detection limit of 0.12 ng/mL was obtained at the optimized extraction conditions, and the calibration plot was linear in the concentration range of 0.30-200 ng/mL. With relatively low limit of detection and good precisions, the proposed method has the potential for the extraction and determination of methadone in biological samples.