Organic carbon determination

Pu distribution ratios and dissolved organic carbon determination... 

One of the best-known commercial instruments developed for organic carbon determinations is the Beckman total carbon analyser, which utilises an analysis scheme developed by Van Hall and co-workers [57,99]. This instrument works reasonably well in fresh water. It has become a standard instrument in pollution control and water treatment [103]. The Beckman instrument has not worked as satisfactorily for seawater because of the latter s high carbonate and low organic content. 

Ratio of microbial biomass to total organic carbon Calculation from individual measures Indicates enrichment of microbial biomass relative to total organic carbon determined in nonstandard laboratory with specialized equipment Rice et al. (1996)... 

Grosjean, D. Solvent extraction and organic carbon determination in atmospheric particulate matter The organic extraction-organic carbon analyzer (OE-OCA) technique. Anal. Chem. 47 797-805, 1975. 

R. Dunn, New Developments in Membrane-Selective Conductometric Instruments for Total Organic Carbon Determination in Water, Am. Lab., September 2004, p. 22. 

B. Wallace and M. Purcell, The Benefits of Nitrogen and Total Organic Carbon Determination by High-Temperature Combustion, Am. Lab. News Ed., February 2003, p. 58. 

Biogenic silicon (BSI) was determined, with minor modifications, by the method of DeMaster (17). As adapted, the technique involved time-course leaching of <20-mg samples of particulate matter in 30 mL of 1.0% Na2C03 in a water bath at 85 °C. Silica in leachates was quantified either colorimetrically (Technicon autoanalyzer procedure) or by nitrous oxide flame atomic absorption. A high-temperature catalytic-combustion technique (Perkin Elmer 240C) was used for particulate organic carbon determinations. Particulate inorganic (carbonate) carbon was measured on the same instrument by CO 2 evolution after treatment of the particles with phosphoric acid. 

Kawata et al. [ 128] have described the effects of headspace conditions on recoveries of volatile organic compounds from sediments and soils. Hewitt [129] compared three vapour partitioning headspace and three solvent extraction methods for the preparation of soil samples for volatile organic carbon determination in soils. Methanol extraction was the most efficient method of spiked volatile organic carbon recovery, which depended on the soil organic carbon content, the octanol-water partitioning coefficients of analytes and the extraction time. 

Vogl, J. and Heumann, K.G. (1998) Development of an ICP-IDMS method for dissolved organic carbon determinations and its application to chromatographic fractions of heavy metal complexes with humic substances. Anal. Chem., 70, 2038-2043. 

Hammes, F.A. and T. Egli. 2005. New method for assimilable organic carbon determination using flow-cytometric enumeration and a natural microbial consortium as inoculum. Environ. Sci. Technol. 39 3289-3294. 

Mancinelli, V., M. Rinaldi, E. Finessi, et al. 2007. An anion-exchange high-performance liquid chromatography method coupled to total organic carbon determination for the analysis of water-soluble organic aerosols./. Chromatogr. A 1149 385-389. 

Humic substances isolated from stream samples from each site fell within these common ranges, with Como Creek humic substances accounting for 55% of the DOC whereas the Suwannee River humic substances accounted for 81 % of the DOC. In contrast, foam humic substances accounted for 93% of the DOC from Como Creek foam and for 89% of the DOC from the Suwannee River foam. Organic carbon determinations were not made on the foam-extract fraction, and the percentage contribution by weight of humic substances to this material could not be determined. 

Dissolved organic carbon (determined by combustion at 680 °C on a Shi-rnadzu TOC-500 instrument) was about 3.5 mg/L and varied little in samples from different depths and times. Alkalinity (determined by Gran plot titrations) was 3-4 mmol/L, and pH varied with depth and time in the range 7.5-8.5 (21). Dissolved phosphate and silicate were measured in filtered samples by standard automated (Auto-Analyzer) methods (25). 

Total organic carbon determination of water samples is an instrumental method originally developed by the Dow Chemical Company [54] and sold commercially by Beckman under license from Dow. Either normal surface-water samples or waste streams high in organics may be analyzed, and samples of only 10—30 xL are required. The result may be used to estimate oxygen demand from the TOC reading [55]. 

Sediments were air-dried in the laboratory and lightly disaggregated. Organic carbon determinations were carried out by the method of... 

The amount of initial organic carbon then is the sum of the preserved organic carbon (measured as TOC) and the metabolized organic carbon (determined from the sulfur content with stoichiometric correction for the sulfate reduction process). Furthermore, the diffusive loss has to be taken into account. With a... 

Van Hall, C.E., Barth, D. and Stenger, V.A., 1965. Elimination of carbonates from aqueous solutions prior to organic carbon determination. Anal. Chem., 37 (6) 769— 771. 

Nitrate reduction rates have been shown to be highly correlated to soil organic matter and soluble or available organic carbon (determined as extractable organic carbon) in soils. Several studies have shown a strong relationship between nitrate reduction and available carbon in soils (Buford and Bremner, 1975 Reddy et al., 1982). Nitrate reduction in wetland soils can be coupled to organic matter mineralization (see Chapter 5), as facultative bacteria use... 

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