ASTM_D_2008_-_12.pdf

Designation:D200812Standard Test Method forUltraviolet Absorbance and Absorptivity of PetroleumProducts1This standard is issued under the fixed designation D2008;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()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers the measurement of the ultra-violet absorption of a variety of petroleum products.It coversthe absorbance of liquids or the absorptivity of liquids andsolids,or both,at wavelengths in the region from 220 to400 nm of the spectrum.1.2 The use of this test method implies that the conditions ofmeasurementwavelength,solvent(if any),sample pathlength,and sample concentrationare specified by referenceto one of the examples of the application of this test method inthe annexes or by a statement of other conditions of measure-ment.1.3 Examples of the application of this test method are theabsorptivity of refined petroleum wax,and the absorptivity ofUSP petrolatum.1.4 The values stated in SI units are to be regarded as thestandard.The values stated in Fahrenheit,feet,and inches,indicated in parentheses,are for information only.1.5 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system,kidney,and liver damage.Mercury,orits vapor,may be hazardous to health and corrosive tomaterials.Caution should be taken when handling mercury andmercury-containing products.See the applicable product Ma-terial Safety Data Sheet(MSDS)for details and EPAs website(http:/www.epa.gov/mercury/faq.htm)for additional informa-tion.Users should be aware that selling mercury or mercury-containing products,or both,in your state may be prohibited bystate law.1.6 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 specificwarning statements,see 7.3.1,7.3.3,and 13.4.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE131 Terminology Relating to Molecular SpectroscopyE169 Practices for General Techniques of Ultraviolet-VisibleQuantitative AnalysisE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers3.Terminology3.1 Definitions of terms and symbols relating to absorptionspectroscopy in this test method shall conform to TerminologyE131.Terms of particular significance are the following:3.2 Definitions:3.2.1 radiant energy,nenergy transmitted as electromag-netic waves.3.2.2 radiant power,P,nthe rate at which energy istransported in a beam of radiant energy.3.2.3 transmittance,T,nthe molecular property of a sub-stance that determines its transportability of radiant power,expressed by:T 5PPo(1)where:P=the radiant power passing through the sample andPo=the radiant power incident upon the sample.3.2.4 absorbance,A,nthe molecular property of a sub-stance that determines its ability to take up radiant power,expressed by:A 5 log101/T!5 2log10T(2)where T is the transmittance as defined in 3.2.3.3.2.4.1 DiscussionAbsorbance expresses the excess ab-sorption over that of a specified reference or standard.It isimplied that compensation has been affected for reflectance1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0F on Absorption Spectroscopic Methods.Current edition approved June 1,2012.Published October 2012.Originallyapproved in 1962.Last previous edition approved in 2009 as D200809.DOI:10.1520/D2008-12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 losses,solvent absorption losses,and refractive effects,ifpresent,and that attenuation by scattering is small comparedwith attenuation by absorption.3.2.5 dilution factor,f,nthe proportion of solvent increasemade to reduce the concentration and thus the absorbance of asolute,expressed by the ratio of the volume of the dilutedsolution to the volume of original solution containing the samequantity of solute as the diluted solution.3.2.6 absorptivity,a,nthe specific property of a substanceto absorb radiant power per unit sample concentration and pathlength,expressed by:a 5 Af/bc(3)where:A=the absorbance defined in 3.2.4,f=the dilution factor defined in 3.2.5,b=sample cell path length,andc=the quantity of abso