Concentrations of total organic carbon on vertical profiles in waters of the North Atlantic in January 1994

Not filtered water samples were taken in 10 ml ampoules (sealed immediately after being acidified with phosphoric acid to pH<2, sampling), or 40 ml screw-lid vials, and measured onboard at sampling or next days, or frozen (-20°C) until being acidified and measured in home labs. Carbon measurement was by high-temperature catalytic oxydation in a 10 cm column packed with 5% Pt on aluminum oxide beads at 900°C in a stream of oxygen, and CO2 detection by infrared extinction after the removal of moisture and SO2 by appropriate traps (cold trap, Mg-percarbonate, Na-pyrophosphate, tin, bronze or Sulfix). The apparatus was the dual channel Dimatek 2000 equipped with a Binos 200 detector.