ASTM_F_2605_-_08e1.pdf

Designation:F2605081Standard Test Method forDetermining the Molar Mass of Sodium Alginate by SizeExclusion Chromatography with Multi-angle Light ScatteringDetection(SEC-MALS)1This standard is issued under the fixed designation F2605;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.1NOTESubsection 6.1.5 was editorially corrected in September 2008.1.Scope1.1 This test method covers the determination of the molarmass of sodium alginate intended for use in biomedical andpharmaceutical applications as well as in tissue engineeredmedical products(TEMPs)by size exclusion chromatographywith multi-angle laser light scattering detection(SEC-MALS).A guide for the characterization of alginate has been publishedas Guide F2064.1.2 Alginate used in TEMPs should be well characterized,including the molar mass and polydispersity(molar massdistribution)in order to ensure uniformity and correct func-tionality in the final product.This test method will assist endusers in choosing the correct alginate for their particularapplication.Alginate may have utility as a scaffold or matrixmaterial for TEMPs,in cell and tissue encapsulationapplications,and in drug delivery formulations.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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:2F2064 Guide for Characterization and Testing of Alginatesas Starting Materials Intended for Use in Biomedical andTissue Engineered Medical Product ApplicationsF2315 Guide for Immobilization or Encapsulation of LivingCells or Tissue in Alginate Gels2.2 United States Pharmacopeia/National Formulary:3 Chromatography2.3 National Institute of Standards and Technology:4NIST SP811 Special Publication:Guide for the Use of theInternational System of Units3.Terminology3.1 Definitions:3.1.1 alginate,na polysaccharide substance extractedfrom brown algae,mainly occurring in the cell walls andintercellular spaces of brown seaweed and kelp.Its mainfunction is to contribute to the strength and flexibility of theseaweed plant.Sodium alginate,and in particular calciumcross-linked alginate gels are used in tissue engineered medicalproducts(TEMPs)as biomedical scaffolds and matrices,forimmobilizing living cells(see Guide F2315)and in drugdelivery systems.3.1.2 molar mass average,nthe given molar mass(Mw)of an alginate will always represent an average of all of themolecules in the population.The most common ways toexpress the molar mass are as the number average(Mn)and themass average(Mw).The two averages are defined by thefollowing equations:Mn5(iNiMi(iNiandMw5(iwiMi(iwi5(iNiMi2(iNiMi(1)where:Ni=number of molecules having a specific molar mass Mi,andwi=mass of molecules having a specific molar mass Mi.1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.42 on Biomaterials and Biomolecules for TEMPs.Current edition approved Feb.1,2008.Published May 2008.DOI:10.1520/F2605-08E01.2For 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.3Available from United States Pharmacopeia and National Formulary,U.S.Pharmaceutical Convention,Inc.(USPC),Rockville,MD.4Available from National Institute of Standards and Technology(NIST),100Bureau Dr.,Stop 1070,Gaithersburg,MD 20899-1070,http:/physics.nist.gov/cuu/Units/bibliography.html.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.2.1 DiscussionIn a polydisperse molecular populationthe relation Mw Mnis always valid.The coefficient Mw/Mnisreferred to as the polydispersity index,and will typically be inthe range 1.5 to 3.0 for commercial alginates.NOTE1The term molecular weight(abbreviated MW)is obsolete andshould be replaced by the SI(Systme Internationale)equivalent of eitherrelative molecular mass(Mr),which reflects the dimensionless ratio of themass of a single molecule to an atomic mass unit(see ISO 31-8),or molarmass(M),which refers to the mass of a mole of a substance and istypicallyexpressedasgrams/mole.Forpolymersandothermacromolecules,use of the symbols Mw,Mn,and Mzcontinue,referringto mass-average molar mass,number-average molar mass,and z-averagemolar mass,respectively.For more information regarding proper uti