Determination of Total Organic Carbon in Water by Thermal Combustion-Ion Chromatography

Abstract

A sensitive method for determining total organic carbon at microgram per liter levels in industrial, environmental, and drinking waters by thermal combustion ion chromatography was developed using tube furnace and readily accessable HPLC equipment. To achieve complete oxidation, persulfate (0.25%) was added to oxidize nonvolatile organic compounds in solution and cupric oxide heated at 900 °C to convert volatile organic compounds to CO(2), which was scrubbed in a 20 mL solution of 50 mM KOH with 10 drops of butanol added. The carbonate anion obtained was determined by nonsuppressed ion chromatography using 0.6 mM potassium hydrogen phthalate (KHP) as the eluent. Both surfactants and volatile 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 μg of C L(-)(1) and 10-2500 μg of C L(-)(1), respectively, and they can be adjusted using samples ranging from 100 mL to 2 L. Good repeatablity (RSD less than 10%) and close to 100% recoveries were obtained for KHP 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 flexible in adjusting the linear range and sensitivity using variable sample sizes.

Determination of Carbetamide in Water by Micro Liquid-Liquid Extraction Followed by HPLC

“…Other methods to overcome these difficulties have also been used, such as noise/signal ratio (S/N = 2 or S/N = 3), with the DL defined as that amount required to give a signal 2 or 3 times the background noise (11)(12)(13). In previous papers, we have been using criteria according to IUPAC recommendations applying it to transient techniques, such as Gas Chromatography (GC) (14), High Performance Capillary Electrophoresis (HPCE) (15), and Differential Pulse Voltammetry (DPV) (16).…”

Chemical Processes in Marine Environments

“…As recommended by Gershey et al (1979), a regression analysis would provide important insights on the importance of blanks. The WCO system proposed by Fung et al (1996) mentioned above would overcome this effect. In a similar manner, the slope of the fitted line gives information about the relative oxidation efficiency.…”

Flow-injection analysis for the determination of total inorganic carbon and total organic carbon in water using the H2O2–luminol–uranine chemiluminescent reaction

“…This leads to great interest in monitoring low levels of organic matter (TOC<1 mg L −1 carbon). In addition, high technology industries such as semiconductor, computer, and laboratory applications also need purer water [6]. Therefore, a sensitive, convenient analytical method for the determination of TIC and TOC is needed.…”

“…For TIC analysis the carbonate is decomposed in samples with acid and for TOC analysis the organic carbon is mineralized via wet or dry combustion, or chemical oxidation [3][4][5][6][7][8]. High-temperature catalytic combustion (HTC) is often employed and has advantages of greater oxidation efficiency and rapid determination.…”

“…High-temperature catalytic combustion (HTC) is often employed and has advantages of greater oxidation efficiency and rapid determination. However, memory effects may arise because of carbon residues depositing on the wall of the HTC column, which may adversely affect the reproducibility and accuracy [3,6,7]. Moreover, the instrumentation is rather expensive.…”