ASTM_E_1812_-_96.pdf

Designation:E 1812 96Standard Practice forOptimization of Flame Atomic Absorption SpectrometricEquipment1This standard is issued under the fixed designation E 1812;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the optimization of flame atomicabsorption spectrometers and the checking of spectrometerperformance criteria.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For specific hazardsassociated with the use of this practice see Practices E 50 andwarning statement included in this practice.2.Referenced Documents2.1 ASTM Standards:E 50 Practices for Apparatus,Reagents,and Safety Precau-tions for Chemical Analysis of Metals2E 863 Practice for Describing Flame Atomic AbsorptionSpectroscopy Equipment3E 1452 Practice for Preparation of Calibration Solutions forSpectrophotometric and Spectroscopic Atomic Analysis33.Significance and Use3.1 This practice is used for optimizing the parameters inthe analysis of metals and alloys by flame atomic absorptionspectrometry and also describes the practice of checking thespectrometer performance.The work is expected to be per-formed in a properly equipped laboratory,and appropriatedisposal procedures are to be followed.4.Apparatus4.1 Atomic Absorption Spectrometer,equipped with anappropriate background corrector,a signal output device(suchas a video display screen,or VDS),a digital computer,a printeror strip chart recorder,and an optional autosampler.4.2 Radiation SourceHollow cathode lamp or electrode-less discharge lamp for the analyte(s).4.3 For a general discussion of the instrumental require-ments for flame atomic absorption see Practice E 863.4.4 For a general discussion of apparatus requirements seePractices E 50.5.Reagents5.1 Purity and Concentration of ReagentsThe purity andconcentration of common chemical reagents shall conform toPractices E 50.The reagents should be free of or containminimal amounts(0.1 g/g)of the analyte of interest.5.2 Calibration SolutionsRefer to the preparation of cali-bration solutions in the relevant analytical method and 7.1.1 ofthis practice.Also refer to Practice E 1452.6.Instrument Adjustments6.1 Determine the flame type(air-acetylene or nitrousoxide/acetylene)to be used by the relevant analytical proce-dure.Set up the atomic absorption spectrometer to operate withthe appropriate single slot laminar flow burner head in accor-dance with the manufacturers instructions.NOTE1Warning:A“flashback”may occur if a nitrous oxide/acetylene flame is used with burners not specifically designed for a nitrousoxide/acetylene flame,particularly on older or more basic instruments.6.2 Use a single-element radiation source(hollow cathodeor electrodeless discharge lamp)as the light source under test.Operate the lamp as directed by the manufacturer.NOTE2The use of multielement lamps is not generally recom-mended,especially if one of the elements contained in them is iron.However,some binary alloy lamps give a more stable emission thansingle-element lamps.6.3 Light the burner and aspirate water until a thermalequilibrium is reached.Pass a cleaning wire through thenebulizer.Check the burner slot for any buildup which mayclog the burner.6.4 Aspirate a mid-range calibration solution of the elementbeing tested and adjust the instrument to give optimumabsorption.Use the wavelength setting specified in the relevantanalytical method.Use the slit setting or bandpass recom-mended by the instrument manufacturer for the element beingtested and the wavelength specified.Adjust the burner heightsand alignment for optimum absorption.The use of scaleexpansion may be necessary.6.5 Adjust the nebulizer for maximum absorption.6.6 Flush the burner system with HCl(1+19),HNO3(1+19),or deionized water and zero the instrument.Proceed1This practice is under the jurisdiction of ASTM Committee E-1 on AnalyticalChemistry for Metals,Ores,and Related Materials and is the direct responsibility ofSubcommittee E01.20 on Fundamental Practices.Current edition approved May 10,1996.Published July 1996.2Annual Book of ASTM Standards,Vol 03.05.3Annual Book of ASTM Standards,Vol 03.06.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.with the instrument performance checks.7.Instrument Performance Checks7.1 The calibration solutions are prepared as described inthe relevant analytical method.Normally five calibration solu-tions are used,including the one containing no analyte(S0).7.1.1 Two pairs of calibration solutions are required for theinstrument performance