Abstract:

A micro-luteolin carbon fiber acidity microelectrode(Lu/CFME) was made with luteolin as a pH sensitive substance, carbon fiber as conductive matrix and solid paraffin as a binder. An all solid state acidity microelectrode set was combinated by Lu/CFME as working electrode, a self-made conductive gel type all-solid micro Ag/AgCl as reference electrode and a platinum wire microelectrode as auxiliary electrode. The response of the electrode set to the effective acidity was studied in the solution of phosphate buffer solution at pH 2.00~10.00 by cyclic voltammetry. The results show that there is a pair of reversible redox peaks on the cyclic voltammetry curve. Their peak potentials(E_pa) were all linear with pH. Based on this, a method for determining the acidity of solution was established by square wave voltammetry, and the linear regression equation for peak potential of oxidation peak and pH is E_pa(V)=-0.0567pH+0.603(r=0.999). The electrode set is micro, non-toxic and anti-interference. It is applied to acidity measurement of trace saliva and sweat on the skin surface, and satisfactory results have been obtained. Therefore, this result provides a technical basis for real-time, in-vivo detection of body fluids.

Key words: luteolin modified acidity microelectrode, micro Ag/AgCl reference electrode, all solid, square wave voltammetry