Extraction and determination of group of volatile organic compounds by headspace - solid phase microextraction - gas chromatography in tea and vegetable samples

In this study, a composite coating of polypyrrole/modified multiwalled carbon nanotubes/modified activated carbon prepared from hazelnut shells (PPy/MWCNTs/AC), was electrochemically synthesized and used for analyzing a group of volatile aromatic hydrocarbons in tea and vegetable samples. In order to obtain an adherent and stable composite coating, the effective parameters on electrodeposition process were optimized using the one-variable-at-a-time procedure, as well as the effective parameters in the desorption step of analytes was performed by this method. Based on the results, the deposition potential of 1 V, the deposition time of 1000 seconds, the desorption temperature of 280 ° C and the desorption time of 5 minutes were considered as the optimal values. To optimize the effective parameters in the extraction stage, the experimental design was used. Finally, the extraction temperature was 25 ° C, the extraction time was 30 minutes and the amount of salt was 10%. The calibration curve for each analyte in a range was linear as follows: 2 ̶ 15 µg ̸ L (fluorene and phenanthrene), 2 ̶ 10 µg ̸ L (anthracene and pyrene) and 0.5 ̶ 8 µg ̸ L (naphthalene). Under the optimized conditions, the amounts of the detection limits (LODs) calculated at S ̸ N proportion of 3, were varied from 0.06 to 0.9 µg ̸ L. The RSDs% of the peak areas ranged between 0.5 and 8.6%.