Detection of secretion from pancreatic islets using chemically modified electrodes.

Secretion of insulin from pancreatic islets was monitored indirectly by detecting zinc. Anodic stripping voltammetric measurements of zinc were done on a bismuth-modified electrode. Comparison of the performance of bismuth-modified electrodes and mercury film electrodes showed that bismuth is an appropriate alternative for Zn detection.

Spectroelectrochemical sensing based on attenuated total internal reflectance stripping voltammetry. 3. Determination of cadmium and copper.

The optical and electrochemical properties of metallic films on ITO surfaces resulting from deposition of copper and cadmium were monitored by stripping voltammetry-attenuated internal reflectance spectroscopy. The voltammetric or optical responses of both metals were examined with respect to solution conditions such as pH and presence of dissolved oxygen. The morphologies of these films were also examined using environmental scanning electron microscopy, and the microscopic electrodeposition patterns were found to influence the optical response.

Spectroelectrochemical sensing based on attenuated total internal reflectance stripping voltammetry. 2. Determination of mercury and lead.

Detection of lead and mercury by attenuated total internal reflectance spectroscopy coupled to stripping voltammetry is demonstrated. Changes in attenuation of light passing through an indium tin oxide optically transparent electrode (ITO-OTE) accompany the electrodeposition and stripping of lead and mercury on the electrode surface. The change in absorbance during stripping of electrodeposited metal constitutes the analytical response that enables detection over a range of 2.

Spectroelectrochemical sensing based on attenuated total internal reflectance stripping voltammetry. 1. Determination of lead and cadmium.

The electrodeposition and subsequent stripping of lead and cadmium on an indium tin oxide (ITO) optically transparent electrode (OTE) were monitored by attenuated total internal reflectance. Light passing through the ITO-OTE is attenuated proportionally to the concentration of metal ion and deposition time. The wavelength dependence of the optical responses of deposited Pb and Cd was determined; optimal performance based on maximum sensor absorbance was at 750 nm for Pb and at 400 nm for Cd.

Development and characterization of simulant pancreatic islets.

Insulin is stored in pancreatic islets as a zinc-insulin complex, and stimulating the islets results in the release of insulin and zinc. Simulant pancreatic islet beads have been developed using agarose beads (50-250 micro m diameter) derivatized with iminodiacetic acid that have been loaded with zinc. A qualitative comparison of the simulant beads with pancreatic islets has been made by staining with dithizone and a zinc-binding fluorescent dye, TSQ.