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Um eletrodo de carbono vítreo modificado com poli(safranina T) foi utilizado para a determinação simultânea de epinefrina (EP) e ácido úrico (AU) na presença de ácido ascórbico (AA). Correntes eletrocatalíticas aumentadas e potenciais bem separados para EP e AU foram observados. As correntes de pico anódico de EP e AU foram lineares em função das concentrações correspondentes, na faixa de 6,0×10. Além disso, o eletrodo modificado mostrou boa sensitividade e estabilidade. Resultados satisfatórios foram alcançados para a determinação de EP e AU em soluções de injeção de EP bem como em amostras de urina humana.A poly(safranine T) modified glassy carbon electrode was used for the simultaneous determination of epinephrine (EP) and uric acid (UA) in the presence of ascorbic acid (AA). Enhanced electrocatalytic currents and well-separated potentials for EP and UA were observed. The anodic peak currents of EP and UA were linear to the corresponding concentrations in the range of 6.0×10 . In addition, the modified electrode showed good sensitivity and stability. Satisfactory results were achieved for the determination of EP and UA in injection solutions of EP and in human urine samples.

Herein, a dual-mode aptasensor for subnanomolar detection of lead ions Pb 2+ based on electrochemiluminescence (ECL) and fast scan voltammetry (FSV) was developed. It could be one-step fabricated using an all-in-one probe Fe 3 O 4 @Au-ssDNA&Ru-NH 2 which has multiple functions: Fe 3 O 4 core achieves one-step preparation of the aptasensor; Au shell provides a place for assembly and electrochemical reactions; ssDNA can selectively recognize and capture target Pb 2+ , and ferrocene labeled on it could provide fast scan voltammetric signal and participate in changes of ECL signals; and Ru-NH 2 is a signal marker for ECL detection. In presence of target Pb 2+ , ssDNA folds to form G-quadruplex, and ferrocene labeled on its end approaches to the Au shell surface resulting in easier electron transfer. So the electrochemical signal is enhanced, and ECL quenching occurs. Electrochemical peak current increased about 1000 times at 100 V s −1 using FSV, making its sensitivity compatible with that of ECL to obtain highly sensitive dual-mode detection. Pb 2+ could be detected in the concentration range from 10 −10 mol l −1 to 10 −6 mol l −1 with a limit of quantitation (LOQ) 10 −10 mol l −1 . Selectivity, stability, reproducibility, accuracy and practicality are good. This extremely simple method provides a valuable idea for developing biosensors for field detection applications.

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