ASTM_E_1507_-_98_2003.pdf

Designation:E 1507 98(Reapproved 2003)Standard Guide forDescribing and Specifying the Spectrometer of an OpticalEmission Direct-Reading Instrument1This standard is issued under the fixed designation E 1507;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 features of a spectrometer or poly-chromator used for optical emission,direct-reading,spectro-chemical analysis.A polychromator in this sense consists of aspectrometer with an extended and fixed wavelength range andan array of fixed exit slits to isolate the spectral lines of theelements to be measured.1.1.1 This guide does not apply to direct-reading systemsthat employ echelle spectrometers and vidicon or other detec-tors where the design parameters are quite different.1.2 This guide covers only the optical portion of theinstrument,from excitation stand to photomultipliers.1.2.1 Only general statements are made about source units.1.2.2 Photomultipliers are included to the extent that theyare mounted within the spectrometer to convert optical inten-sities to electrical signals,and establish the instrumentalprecision of each channel as a light measuring device.Readoutsystems are not included.1.3 It is not the purpose of this guide to establish bindingspecifications or tolerances,but rather,to call attention toimportant parameters that manufacturers should include intheir literature,to provide methods for measuring those param-eters,and to assign values that are indicative of acceptablygood performance.Because of the great variety of demandsimposed by spectrochemical techniques,rigid performancecriteria are not feasible.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafety problems,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.1.6 Apartial listing of the information in this guide includesthe following:SectionTerminology3Background Equivalent Concentration(BEC)3.2.1Channel3.2.2Readability3.2.3Scattered Radiation3.2.4Shot Noise3.2.5White Light Precision3.2.6Working Resolution3.2.7Fundamental Spectrochemical Objectives5Accuracy5.2Precise Photometry5.2.1Bias in Photometry5.2.2Detection and Determination Limits5.3Minimization of Interference5.4Parameters of Spectrometer and Associated Components6Dispersion,Reciprocal Linear6.2Working Resolution6.3Speed or Radiation Throughput6.4White Light Precision6.5Scattered Light6.6Slits6.7Accuracy of Positioning Exit Slits6.7.3Wavelength Coverage and Focal Curve Length6.8Secondary Optics6.9Optical Stability6.10Spectrometer Illumination6.11Astigmatic Image6.12Excitation Stands6.13Vacuum Systems6.14Flushing With Transparent Gas(Nitrogen)6.15Other,Including Maintenance Features6.16-6.18Measuring Specified Polychromator Parameters7Working Resolution7.1-7.4Line Interference7.5White Light Precision7.6Scattered Light7.7Optical Alignment and Focus7.8Optical Stability7.9Precision and Accuracy7.10Describing the Spectrometer in Analytical Methods8Wavelength Coverage and Reciprocal Dispersion8.2.1Working Resolution8.2.2Entrance and Exit Slit Widths8.2.3Low Concentrations8.2.4High Concentrations8.2.5Varying Parameters on Working Resolution and ThroughputAppendix X1DispersionX1.2Size of SpectrometerX1.3Effects of Slit WidthsX1.4Recommended Spectral Lines for Measuring Working Reso-utionAppendix X2Photographic Speed Versus Photoelectric ThroughputAppendix X3Photographic SpeedX3.1Polychromator Radiation ThroughputX3.2Calculation of Radiation ThroughputX3.31This guide is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals,Ores,and Related Materials and is the direct responsibility ofSubcommittee E01.20 on Fundamental Practices.Current edition approved June 10,2003.Published September 2003.Originallyapproved in 1993.Last previous edition approved in 1998 as E 1507-98.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.Typical Radiation ThroughputsX3.42.Referenced Documents2.1 ASTM Standards:E 135 Terminology Relating to Analytical Chemistry forMetals,Ores,and Related Materials2E 172 Practice for Describing and Specifying the ExcitationSource in Emission Spectrochemical Analysis3E 356 Practices for Describing and Specifying the Spec-trograph4E 380 Practice for Use of the International System of Units(SI)(The Modernized Metric System)5E 520 Practice for Describing Photomultiplier Detectors inEmission and Absorption Spectroscopy2E 876 Practice for Use of Statistics in the Evaluation ofSpectrometric Data23.Terminology3.1 DefinitionsFor definitions of terms us