Amperometric biosensor for determining lead and cadmium

A method for the determination of lead and cadmiun in plant leaves and the semiquantitative determination of these metals in soils using an amperometr ic tissue biosensor based on cucumber leaves is proposed. The effect of lea d and cadmium ions on the enzymatic hydrolysis of cysteine has been studied in the presence of L-cysteine desulfhydrolase from cucumber leaves. It has been found that ions of these metals have an inhibiting effect on the enzy me of cysteine metabolism. This effect is proportional to the metal concent ration and the time of treating the biosensitive part of the biosensor with the salts of these metals. The detection limits for cadmium and lead attai ned with the proposed sensor are 1 x 10(-8) and 3 x 10(-8) M, respectively.