Selective and sensitive determination of uric acid at DNA-modified graphite powder microelectrodes

DNA-modified graphite powder microelectrodes (DNA/GPMEs) were used for selective and sensitive detection of uric acid (UA) in urine samples by differential pulse voltammetry (DPV). Under optimal conditions the powder microelectrode technique combined with DNA immobilization on the surface of graphite powder can effectively eliminate the interference of ascorbic acid (AA) and greatly improve the detection sensitivity. In a citrate-phosphate buffer solution (pH 5.5) the difference in oxidation peak potentials (ΔEp) between UA and AA reached to 360 mV, and the linear response range for detection of UA was 1.0 × 10−7-5.0 × 10−5 mol/L, with a detection limit of 5.0 × 10−8 mol/L. UA in real human urine can be determined using DNA/GPMEs without any pretreatment of samples, giving satisfactory results.