Rapid Determination of Dissolved Organic Carbon by Persulfate Oxidation Vial and Uv/vis Spectrophotometer

Abstract

Dissolved organic carbon (DOC) has long been studied to determine and characterize natural organic matter (NOM). The goal of this thesis is to test a simplified ultraviolet-visible (UV/VIS) spectrophotometric procedure for determination and characterization of dissolved organic carbon (DOC) in water using the TOC direct method (HACH Company). Laboratory tests of known samples were analyzed by this technique to ascertain the performance (precision and accuracy) and its applicability as an alternative to traditional measurements. The detection limitation of the method has been determined through a laboratory method detection limits guide from an EPA certification program, and the method detection limit was calculated to be 1.00 mg/L. The value of this concentration is slightly larger than the given lower limits of 0.3 mg/L expected. For most of the organic matter, the resulting data indicated that the TOC direct method is easy to use, accurate and effective for determining the carbon content. However, for large, complex organic particles, such as humic acid, their DOC may be underestimated due to incomplete persulfate oxidation. Careful handling and practice is very necessary to achieve the optimal of the method performance. The method is easily prepared and portable compared with the traditional DOC analyzer, while the reagent solution and equipment is minimal.