【国外标准】 Standard Practice for Micro-Extraction of Water for Analysis of Volatile and Semi-Volatile Organic Compounds in Water

4.1 This practice provides a general procedure for the solvent extraction of volatile and semi-volatile organic compounds from a water matrix. Solvent extraction is used as the initial step in the solvent extraction of organic constituents for the purpose of quantifying extractable organic compounds.4.2 Typical detection limits that can be achieved using micro-extraction techniques with gas chromatography (GC) with flame ionization detector (FID), electron capture detector (ECD), or with a mass spectrometer (GC/MS) range from milligrams per litre (mg/L) to nanograms per litre (ng/L). The detection limit, linear concentration range, and sensitivity of the test method for a specific organic compound will depend upon the sample clean-up, injection volume, solvent to sample ratio, solvent concentration methods used, and the determinative technique employed.4.3 Micro-extraction has the advantage of speed, simple extraction devices, and the use of small amounts of sample and solvents.4.3.1 Selectivity can be improved by the choice of solvent (usually hexane or pentane) or mixed solvents, extraction time and temperature, and ionic strength of the solution.4.3.2 Extraction devices can vary from the sample container itself to commercial devices specifically designed for micro-extraction. See 7.1 and 7.2.4.3.3 A list of chlorinated organic compounds that can be determined by this practice includes both high and low boiling compounds or chemicals (see Table 1).(A) Based on the injection of chlorinated compounds in pentane solution, taking into consideration the 100:1 concentration of a water sample by the microextraction technique.1.1 This practice covers standard procedures for extraction of volatile and semi-volatile organic compounds from water using small volumes of solvents.1.2 The compounds of interest must have a greater solubility in the organic solvent than the water phase.1.3 Not all of the solvents that can be used in micro extraction are addressed in this practice. The applicability of a solvent to extract the compound(s) of interest must be demonstrated before use.1.4 This practice provides sample extracts suitable for any technique amenable to solvent injection such as gas chromatography or high performance liquid chromatography (HPLC).1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 91.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.