Sensing performance, amperometric sensor

Sensing performance for H-,. Sensing performance of the amperometric sensor was examined for the detection of H2 in air. Figure 3 shows the response curve for 2000 ppm H2 in air at room temperature. The response was studied by changing the atmosphere of the sensing electrode from an air flow to the sample gas flow. With air the short circuit current between two electrodes was zero. On contact with the sample gas flow, the current increased rapidly. The 90% response time was about 10 seconds and the stationary current value was 10yUA. When the air flow was resumed, the current returned to zero within about 20 seconds. 

Long Term Performance of Sensors. The sensors showed excellent long term stability stored in buffer at 4 °C. Table 1 shows the long term performance of four typical biosensors. The usual current response to 6 mM glucose for a new biosensor is about 2 fiA. The precision of the absolute current response to 6 mM glucose remains within 15 % for up to four months. This level of precision is unusual for amperometric biosensors. Normally, variations in current are compensated by calibration. The sensitivity of the biosensors, as indicated by the slope of the response, is also stable. This stability is due to the film which maintains the ferrocene within the sensing layer. Biosensors with adsorbed mediator and immobilized enzyme but without film are not stable for any period of... 

Ozoemena [125] performed the anodic oxidation and amperometric sensing of hydrazine using a glassy carbon electrode modified with a cobalt(ll) phthalocya-nine-cobalt(n) tetraphenylporphyrin (CoPc-(CoTPP)4) supramolecular complex. This amperometric sensor displayed excellent characteristics for the determination of hydrazine in 0.2 M NaOH at low overpotential (+100 mV vs. Ag/AgCl), with very fast amperometric response time (1 s), linear range of 10-230 pmol LT, limit of detection of 1 pmol L and sensitivity of 0.0157 pA L pmol . ... 

N. Barsan, J.R. Stetter, M. Findlay, and W. Gopel. High performance gas sensing of CO Comparative tests for semiconducting (Sn02-based) and for amperometric gas sensors . Analytical Chemistry 71 (1999), 2512-2517. 

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