The present invention discloses an optical detection cell for detecting inorganic analytes in an aquatic environment. The optical detection cell comprises a microfluidic channel defining an optical detection path. First and second transparent windows are bonded at opposite locations on the microfluidic channel. The optical detection cell is provided with a UV-LED, and light detector respectively positioned proximally to the first and second transparent windows. The UV-LED configured to be driven by a constant electrical current having a value between 2.5 mA and 50.0 mA.