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| Determination of oxidation induction time of oil by N-doped graphene modified screen printed electrode |
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| KeyWord:N-doped graphene screen printed electrode oil oxidation induction time AC impedance method |
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| Abstract: |
| A novel measurement system for the determination of oxidation induction time of oil by nitrogen-doped graphene （NRG） modified screen printed electrodes with AC impedance spectroscopy (EIS) was constructed. The electrode composition and the conditions of impedance measurement were optimized, and the relation between impedance and peroxide value with time was studied. The results showed that the optimal conditions were obtained as follows: formula for conductive carbon paste of mass ratio of graphene oxide to carbon nano-tube to foliate graphite to Tetraetho-xysiloxane (TEOS) 0.1∶?0.1∶?1∶?2, NRG modification 3 μL, phosphate buffer liquid(pH=7.0) as the supporting electrolyte, acetonitrile and phosphate buffer liquid (pH=7.0) with volume ratio of 1∶?2 as extractant,volume ratio of oil to extractant 1∶?1, flow rate 1.5 mL/min and measurement frequency （5-8）×105 Hz. Under these conditions, the extractant could rapidly and efficiently extract the polar and weak polar oxidation products produced in the process of oil oxidation.The established measurement system could sensitively detect the impedance and its changes of the extracted phase. Moreover, the relative deviation between the oxidation induction time obtained from the impedance-time curve and from the national standard method was less than 5%. F-test and t-test revealed that there was no systematic error between the two methods. |
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