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METALS (Atomic Absorption Methods) 1 Scope and ApplIcatIOn 11 Metals m solutIOn may be readl1y determmed by atomIC absorptIOn spectroscopy The method IS sImple, rapId, and applIcable to a large number ofmetals m dnnkmg, surface, and salme waters, and domestIc and mdustnal wastes Whl1e dnnkmg waters free of particulate matter may be analyzed dIrectly, domestIc and mdustnal wastes reqUlre processmg to solubIlIze suspended matenal Sludges, sedIments and other solId type samples may also be analyzed after proper pretreatment 12 DetectIOn lImIts, sensItIvIty and optImum ranges of the metals w111 vary wIth the vanous makes and models of satIsfactory atomIc absorptIOn spectrophotometers The data shown m Table 1, however, prOVIde some mdlcatIOn of the actual concentratIOn ranges measurable by dIrect aSpIratIOn and usmg furnace techmques In the ma]onty of mstances the concentratIOn range shown m the table by dIrect aspIratIOn may be extended much lower wIth scale expansIOn and conversely extended upwards by usmg a less sensItive wavelength or by rotatmg the burner head Detection lImIts by dIrect aspIratIOn may also be extended through concentratIOn of the sample and/or through solvent extractIOn techmques Lower concentratIOns may also be determmed usmg the furnace technIques The concentratIOn ranges gIven m Table 1 are somewhat dependent on eqUlpment such as the type of spectrophotometer and furnace accessory, the energy source and the degree of electncal expanSIOn of the output SIgnal When usmg furnace techmques, however, the analyst should be cautIOned as to pOSSIble chemlCal reactIOns occurrmg at elevated temperatures WhICh may result m eIther suppressIOn or enhancement of the analysIs element To msure valId data wIth furnace techmques, the analyst must examme each matnx for mterference effects (see 5 2 1) and Ifdetected, treat accordmgly usmg eIther succeSSIve dl1utIOn, matnx modIficatIOn or method of standard addItions (see 8 5) 13 Where dIrect aspIratIOn atomlC absorptIOn techmques do not prOVIde adequate sensItIvIty, m addItion to the furnace procedure, reference IS made to specIalIzed procedures such as the gaseous hydnde method for arsemc and selemum, the cold vapor techmque for mercury, and the chelatIOn-extractIOn procedure for selected metals Reference to approved colonmetnc methods IS also made 14 AtomlC absorptIOn procedures are prOVIded as the methods of chOlce, however, other mstrumental methods have also been shown to be capable of producmg precIse and accurate analytIcal data These mstrumental techmques mc1ude emIssIon spectroscopy, X-ray fluorescence, spark source mass spectroscopy, and anodIc stnppmg to name but a few The analyst should be cautIOned that these methods are hIghly speclahzed techmques requmng a hIgh degree of SkIll to mterpret results and obtam valId data Approved for NPDES and SDWA Issued 1969 Edltonal reVISIOn 1974 and 1978 METALS-lPDF Image | Methods for Chemical Analysis of Water and Wastes
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