ASTM_E_1024_-_97.pdf

Designation:E 1024 97Standard Guide forChemical Analysis of Metals and Metal Bearing Ores byFlame Atomic Absorption Spectrophotometry1This standard is issued under the fixed designation E 1024;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 guide covers general recommendations for the useof atomic absorption spectrophotometers in the flame mode forthe chemical analysis of Metals and metal bearing ores byASTM methods.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.2.Referenced Documents2.1 ASTM Standards:E 50 Practice 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 Analysis3E 1812 Practice for Optimization of Flame Atomic Absorp-tion Spectrometric Equipment33.Significance and Use3.1 The precision and accuracy of atomic absorption analy-ses are influenced by many factors.Most important of thesefactors are the proper preparation of the test solutions,theproper selection and preparation of calibration solutions,andinstrument-related factors,such as proper setting of instrumentparameters,the proper sequence of calibration and test solutionmeasurements,and correct interpretation of the instrumentsresponse.An ASTM method that refers to this guide specifiesthe procedures for preparation of test and calibration solutions.This guide gives the instrument-related procedures for usingthe atomic absorption spectrophotometer in the flame modeand calculating the results.3.2 Because atomic absorption spectrophotometers varygreatly in their sensitivity for any specific element,the con-centration ranges for test and calibration solutions given ineach method must be considered only a guide for analysts whoare not familiar with the response of their instruments for theelement to be determined.Those who know the optimumconcentration range of their instrument should prepare calibra-tion solutions based upon that knowledge.3.3 This guide is based upon simple graphical or mathemati-cal ratio interpolations of instrument response between calibra-tion points.For this reason,the criterion for“curve linearity”isconservative in order to minimize the error introduced by alinear approximation to,or manual graphing of,a markedlycurvilinear response.Other methods of relating concentrationto instrument response(such as,microprocessor curve-fittingtechniques)may be valid for concentrations higher than thelimit posed by the“curve linearity”test in this guide.None ofthese methods have been universally adopted and each methodthat has been proposed achieves its highest precision only indealing with certain cases.The methods given in this guide areuniversally applicable.If employed carefully,they will providesatisfactory precision and accuracy.4.Interferences4.1 Chemical and spectral interferences from sample matrixelements and solvent medium anions are common.The stan-dard method that references this guide will have provided theappropriate remedy:prechemical isolation of the analyte spe-cies,the addition of matrix-modifying reagents,or the speci-fication of special calibration procedures.4.2 Ionization of the analyte element in the flame is afrequent problem since only ground-state atoms are measured.If this effect is significant,the standard method that referencesthis guide will have specified the addition of ionizationsuppressant or other means to minimize it.5.Concentration Range5.1 Prepare the reference and calibration solution as di-rected in 7.1 and 7.2 and in accordance with Practice E 1452,using as a guide the concentrations suggested in the standardmethod.5.2 Prepare the instrument and perform the instrumentperformance checks according to Practice E 1812.5.3 If the criteria for readability and linearity are met,theinitial concentration range may be considered acceptable.Proceed as directed in 6.1.5.1This guide 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 Nov.10,1997.Published June 1998.Originallypublished as E 1024 84.Last previous edition E 1024 84(1994)e1.2Annual 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.5.4 If adequate instrument response is not obtained,prepare