Paper disk on screen printed electrode for one-step sensing with an internal standard.

A point-of-care device, an ideal application is to provide a direct answer for an analysis with only a simple sample introduction. In order to meet the requirements, reagents storage, and self-calibration must be integrated on the portable device. This study describes a device with a paper disk impregnated with reagents including an internal standard and buffer on a screen printed electrode leading to accurate result in a single-step assay. We demonstrated on the applicability of this device by detection of trace lead (ppb level) in 10 μL solution based on the simultaneous (in situ) plating of bismuth and heavy metals onto electrode, which formed alloys followed by anodic stripping, Zn(II) was employed as an internal standard. We believe this approach is attractive for use in field based portable devices.