Carbon measurements in aqueous samples using oxidation at elevated temperatures and pressures created by resistive heating

A method for treating a liquid sample containing organic material utilizing a liquid sample treatment apparatus, the method comprising the steps of:

• providing a liquid sample treatment apparatus comprising the following features:
• a reactor having reactor inlet and reactor outlet ports and a reactor interior for containing the liquid sample under above-ambient temperature and pressure conditions;
• high-pressure fluid reactor valve members at said reactor inlet and reactor outlet ports, said reactor valve members configured to allow a fluid to flow respectively into or out of the reactor interior when in an open-valve mode or, alternatively, configured to seal the reactor interior when in a closed-valve mode;
• a reactor heating system comprising an electrical current source operably connected to the reactor, the electrical current source configured to pass an electrical current through the reactor to rapidly and cyclically heat the reactor interior and the liquid sample sealed in the reactor interior to a temperature of about 150° C. to 650° C. or higher, while the reactor interior and the reactor valve members maintain the liquid sample under sealed conditions;
• and
• a reactor cooling system adapted for rapidly and cyclically cooling the reactor interior and a reactor product sealed in the reactor interior following a heating cycle;
• mixing a known volume of the liquid sample with one or more other liquids selected from oxidizer, acid and dilution water to form a sample mixture;
• flowing at least a portion of the sample mixture into the interior of the reactor using the high-pressure fluid reactor valve members at said reactor inlet and reactor outlet ports, said reactor being adapted to be alternately and repeatedly opened and sealed at the reactor inlet and reactor outlet ports, said sample mixture containing the organic material;
• sealing the portion of sample mixture in the interior of the reactor by closing the valve members at the reactor inlet and reactor outlet ports;
• passing the electrical current through the reactor for a time sufficient substantially to heat and oxidize the organic material contained in the sample mixture and form the reactor product;
• stopping the heating step and then rapidly cooling the interior of the reactor and the reactor product inside to substantially ambient conditions to form cooled liquid and gaseous reactor products;
• and
• opening the reactor and removing the cooled liquid and gaseous reactor products form the reactor interior.