The present invention provides an apparatus and method for measuring carbon (any one or all of TC, TOC, or TIC) in a sample matrix. In an embodiment, a method for measuring carbon in a sample composition is provided. The method comprises providing an apparatus comprising a reaction chamber and a diamond coated electrode, wherein the diamond coated electrode is doped with boron. The apparatus further comprises a detector. In addition, the method comprises contacting the sample composition with the electrode. The method further comprises applying an alternating current to the electrode at a sufficient voltage to produce carbon dioxide. Moreover, the method comprises measuring the amount of carbon dioxide produced.