Development of Integrated In Situ Analyzer for Manganese (IISA-Mn) in Deep Sea Environment

Manganese is a metal ion that can be found at ultra trace level in the ocean. Mainly, manganese comes into the ocean through hydrothermal vents. Usually, determination of manganese concentration is done by sampling seawater in bottles and measuring afterward onboard a ship or in a lab on the ground. Major drawbacks of that method are that only a few samples can be taken at a time and that there is always a risk of contaminations. The use of microfabrication techniques to produce an in situ microanalyzer that can be installed in Autonomous Underwater Vehicles (AUVs) or Remotely Operated Vehicles (ROVs) can overcome these issues. Miniaturization is an asset for mounting an analyzer in AUVs or ROVs due to low total volume (less reagents) and electrical consumption, and for increasing spatial and temporal resolution (higher rate of sampling) to make 3D manganese cartography possible. Here we show the development of an integrated in-situ analyzer for manganese based on chemiluminescence detection. Manganese catalyzes the decomposition of H₂O₂ into radicals OHldr that react with luminol to produce light, which intensity is proportional to Mn²⁺ concentration. Reagents are brought by syringe pumps or pressure-proof mieropumps to a reaction chamber made of polydimethylsiloxane (PDMS) material.