5.1 This test method is necessary because of the need for rapid reliable tests for carbonaceous material in waters and sediments.

5.2 It is used for determining the concentration of organic carbon in water that comes from a variety of natural, domestic, and industrial sources. Typically, these measurements are used to monitor organic pollutants in domestic and industrial waste water.

5.3 When a sample is homogenized so that particulate, immiscible phases, and dissolved carbon from both organic and inorganic sources is determined, the measurement is called total carbon (TC). When inorganic carbon response is eliminated by removing the dissolved CO₂ prior to the analysis or the dissolved CO₂ concentration subtracted from the total carbon concentration, the measurement is called total organic carbon (TOC). When particulates and immiscible phases are removed prior to analysis the measurement is called dissolved carbon (DC), or dissolved organic carbon (DOC) if inorganic carbon response has been eliminated.

5.4 Homogenizing or sparging of a sample, or both, may cause loss of volatile organics, thus yielding a negative error. The extent and significance of such losses must be evaluated on an individual basis. If significant quantities of volatile carbonaceous materials are present or may be present in samples organic carbon should be determined by the difference between the total carbon and the inorganic carbon concentrations. When organic carbon determined both by difference and by sparging agree it is acceptable to determine organic carbon by sparging for similar samples.

5.5 The relationship of TOC to other water quality parameters such as COD and BOD is described in the literature.⁵

1.1 This test method covers the determination of total and organic carbon in water and waste water, including brackish waters and brines in the range from 2 to 20 000 mg/L. This test method has the advantages of a wide range of concentration which may be determined without sample dilution and the provision for boat or capillary introduction of samples containing sediments and particulate matter where syringe injection is inappropriate.

1.2 This procedure is applicable only to that carbonaceous matter in the sample that can be introduced into the reaction zone. When syringe injection is used to introduce samples into the combustion zone, the syringe needle opening size limits the maximum size of particles that can be present in samples. Sludge and sediment samples must be homogenized prior to sampling with a micropipetor or other appropriate sampler and ladle introduction into the combustion zone is required.

1.3 The precision and bias information reported in this test method was obtained in collaborative testing that included waters of the following types: distilled, deionized, potable, natural, brine, municipal and industrial waste, and water derived from oil shale retorting. Since the precision and bias information reported may not apply to waters of all matrices, it is the user's responsibility to ensure the validity of this test method on samples of other matrices.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 9.1 and 10.2.1.