EPA Method 8440 Total Recoverable Petroleum Hydrocarbons by Infrared Spectrophotometry - Revision 0
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FBE7219FA36A4BE0A32793EDA58E5584 |
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0.04 |
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页数： |
8 |
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日期： |
2003-1-16 |
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CD-ROM 8440 - 1 Revision 0,December 1996,METHOD 8440,TOTAL RECOVERABLE PETROLEUM HYDROCARBONS BY INFRARED,SPECTROPHOTOMETRY,1.0 SCOPE AND APPLICATION,1.1 Method 8440 (formerly Draft Method 9073) is used for the measurement of total,recoverable petroleum hydrocarbons (TRPHs) extracted with supercritical carbon dioxide from,sediment, soil and sludge samples using Method 3560.,1.2 Method 8440 is not applicable to the measurement of gasoline and other volatile,petroleum fractions, because of evaporative losses.,1.3 Method 8440 can detect TRPHs at concentrations of 10 mg/L in extracts. This translates,to 10 mg/Kg in soils when a 3 g sample is extracted by SFE (assuming 100 percent extraction,efficiency), and the final extract volume is 3 mL.,1.4 This method is restricted to use by or under the supervision of trained analysts. Each,analyst must demonstrate the ability to generate acceptable results with this method.,2.0 SUMMARY OF METHOD,2.1 Soil samples are extracted with supercritical carbon dioxide using Method 3560.,Interferences are removed with silica gel, either by shaking the extract with loose silica gel, or by,passing it through a silica gel solid-phase extraction cartridge. After infrared (IR) analysis of the,extract, TRPHs are quantitated by direct comparison with standards.,3.0 INTERFERENCES,3.1 The analyte class being measured (TRPHs) is defined within the context of this method.,The measurement may be subject to interferences, and the results should be interpreted accordingly.,3.2 Determination of TRPHs is a measure of mineral oils only, and does not include the,biodegradable animal greases and vegetable oils captured in oil and grease measurements. These,non-mineral-oil contaminants may cause positive interferences with IR analysis, if they are not,completely removed by the silica gel cleanup.,3.3 Method 8440 is not appropriate for use in the analysis of gasoline and other volatile,petroleum fractions because these fractions evaporate during sample preparation.,4.0 APPARATUS AND MATERIALS,4.1 Infrared spectrophotometer - Scanning or fixed wavelength, for measurement around,2950 cm-1.,4.2 IR cells - 10 mm, 50 mm, and 100 mm pathlength, sodium chloride or IR-grade glass.,CD-ROM 8440 - 2 Revision 0,December 1996,4.3 Magnetic stirrer with polytetrafluoroethylene (PTFE)-coated stirring bars.,4.4 Optional - A vacuum manifold consisting of glass vacuum basin, collection rack and,funnel, collection vials, replaceable stainless steel delivery tips, built-in vacuum bleed valve and,gauge is recommended for use when silica gel cartridges are used. The system is connected to a,vacuum pump or water aspirator through a vacuum trap made from a 500 mL sidearm flask fitted,with a one-hole stopper and glass tubing.,5.0 REAGENTS,5.1 Reagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is,intended that all reagents shall conform to the specifications of the Committee on Analytical,Reagents of the American Chemical Society, where such specifications are available. Other grades,may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its,use without lessening the accuracy of the determination.,5.2 Tetrachloroethylene, C Cl - spectrophotometric grade, or equivalent. 2 4,5.3 Raw materials for reference oil mixture - spectrophotometric grade, or equivalent.,5.3.1 n-Hexadecane, CH (CH ) CH 3 2 14 3,5.3.2 Isooctane, (CH ) CCH CH(CH ) 3 3 2 3 2,5.3.3 Chlorobenzene, C H Cl 6 5,5.4 Silica gel.,5.4.1 Silica gel solid-phase extraction cartridges (40 μm particles, 60 A pores), 0.5 g,Supelco, J.T. Baker, or equivalent.,5.4.2 Silica gel, 60 to 200 mesh, Davidson Grade 950 or equivalent (deactivated with,1 to 2 percent water).,5.5 Calibration mixtures:,5.5.1 The material of interest, if available, or the same type of petroleum fraction, if it,is known and original sample is unavailable, shall be used for preparation of calibration,standards. Reference oil is to be used only for unknowns. Whenever possible, a GC,fingerprint should be run on unknowns to determine the petroleum fraction type.,5.5.2 Reference oil - Pipet 15.0 mL n-hexadecane, 15.0 mL isooctane, and 10.0 mL,chlorobenzene into a 50 mL glass-stoppered bottle. Maintain the integrity of the mixture by,keeping stoppered except when withdrawing aliquots. Refrigerate at 4EC when not in use.,5.5.3 Stock standard - Pipet 0.5 mL calibration standard (Section 5.5.1 or 5.5.2) into,a tared 100 mL volumetric flask and stopper immediately. Weigh and dilute to volume with,tetrachloroethylene.,5.5.4 Working standards - Pipet appropriate volumes of stock standard (Sec. 5.5.3) into……
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