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<br />3.4 If the analyte is not completely volatilized and removed from the <br />~ furnace during atomization, memory effects will occur. If this situation is <br />i detected, the tube should be cleaned by operating the furnace at full power at <br />regular intervals in the analytical scheme. <br />3.5 Selenium analysis suffers interference from chlorides (>800 mg/ U and <br />sulfate (>200 mg/L). The addition of nickel nitrate such that the final <br />concentration is 1% nickel will lessen this interference. <br />4.0 APPARATUS ANO MATERIALS <br />4.1 250-mL Griffin beaker. <br />4.2 10 mL volumetric flasks. <br />4.3 Atomic absorption s~ectroohotometer; Single- or dual-channel, <br />', single- or double beam instrument with a grating monochromator, photomultiplier <br />detector, adjustable slits, a wavelength range of 190-800 nm, and provisions for <br />simultaneous background correction and interfacing with a strip-chart recorder. <br />4.4 Selenium hollow cathode lamp or electrodeless discharge lamp (EDU <br />EDLs provide better sensitivity for the analysis of Se. <br />4.5 Graphite furnace: Any graphite furnace device with the appropriate <br />temperature and timing controls. <br />4.6 Strip-chart recorder: A recorder is strongly recommended for furnace <br />work so that there will be a permanent record and so that any problems with the <br />analysis, such as drift, incomplete atomization, losses during charring, changes <br />in sensitivity, etc., can easily be recognized. <br />4.7 Pipets: Microliter with disposable tips. Sizes can range from <br />5 to 1,000 uL, as required. <br />5.0 REAGENTS <br />5.1 ASTM Tvpe II water (ASTM D1193): Water should be monitored for <br />impurities. <br />5.2 Concentrated nitric acid (HNO,): Acid should be analyzed to <br />determine levels of impurities. If a method blank made with the acid is <MDL. <br />the acid can be used. <br />5.3. ~drogen peroxide (30%): Oxidant should be analyzed to determine <br />levels of impurities. If a method blank made with the oxidant is <MDL, the <br />oxidant can be used. <br />7740 - 2 <br />CD-ROM Revision 0 <br />Date S~,ptember 1986 <br />