Lab-on-a-Cable for electrochemical monitoring of phenolic contaminants

The "Lab-on-a-Cable" concept, based on scaling down an electrochemical flow system to a cable platform, is described. The system integrates the analyte collection and the sample handling, with the electrochemical detection of the reaction product in a sealed cylindrical unit, connected to a long shielded cable. An enzymatic assay, involving collection of a phenolic substrate, its mixing with an internally delivered tyrosinase solution, and amperometric detection of the liberated quinone product, is used for illustrating the operation of the flow probe and demonstrating its advantages over remote phenol sensors. The internal buffer solution ensures independence of sample conditions such as pH, ionic strength, or natural conditions, that commonly influences the performance of remote sensors. The "built-in" flow pulsation of the integrated micropump is exploited for a sensitive hydrodynamic-modulation voltammetric detection of hydrazine and peroxide pollutants.