DETERMINATION OF TOTAL ORGANIC-CARBON IN WATER BY THERMAL COMBUSTION-ION CHROMATOGRAPHY

sensitive method for determining total organic carbon at microgram per liter levels in industrial, environmental, and drinking waters by the rmal combustion ion chromatography was developed using tube furnace an d readily accessable HPLC equipment. To achieve complete oxidation, pe rsulfate (0.25%) was added to oxidize nonvolatile organic compounds in solution and cupric oxide heated at 900 degrees C to convert volatile organic compounds to CO2, which was scrubbed in a 20 mt solution of 5 0 mM KOH with 10 drops of butanol added. The carbonate anion obtained was determined by nonsuppressed ion chromatography using 0.6 mM potass ium hydrogen phthalate (KHP) as the eluent. Both surfactants and volat ile and nonvolatile organic compounds commonly found in environmental waters give highly repeatable recoveries close to 100%. The detection limit (S/N = 2) and linear range for a 1 L water sample are 2 mu g of C L(-1) and 10-2500 mu g of C L-l, respectively, and they can be adjus ted using samples ranging from 100 mt to 2 L. Good repeatablity (RSD l ess than 10%) and close to 100% recoveries were obtained for IMP added to real samples such as deionized, mineral, tap, and river water and seawater, Compared with the ASTM D2579 method, the method developed is 3 orders of magnitude more sensitive, more accurate, and reliable in determining samples with low total organic carbon values and more flex ible in adjusting the linear range and sensitivity using variable samp le sizes.