1、Designation:F260516Standard 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
2、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.Scope1.1 This test method covers the determination of the molarmass(typic
3、ally expressed as grams/mole)of sodium alginateintended for use in biomedical and pharmaceutical applicationsas well as in tissue-engineered medical products(TEMPs)bysize exclusion chromatography with multi-angle laser lightscattering detection(SEC-MALS).A guide for the character-ization of alginate
4、 has been published as 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 al
5、ginate 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 this
6、standard.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.Referen
7、ced 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 P
8、harmacopeia/National Formulary:3 Chromatography2.3 National Institute of Standards and Technology:4NIST SP811 Special Publication:Guide for the Use of theInternational System of Units2.4 ISO Standards:5ISO 31-8 Quantities and units-Part 8:Physical chemistryand molecular physics3.Terminology3.1 Defin
9、itions: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
10、 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 i
11、n 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)1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surg
12、ical Materials and Devices and is the direct responsibility of SubcommitteeF04.42 on Biomaterials and Biomolecules for TEMPs.Current edition approved May 1,2016.Published June 2016.Originallyapproved in 2008.Last previous edition approved in 2008 as F2605 081.DOI:10.1520/F2605-16.2For referenced AST
13、M 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
14、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.5Available from International Organization for Standardization(ISO),ISOCentral Secretariat,BIB
15、C II,Chemin de Blandonnet 8,CP 401,1214 Vernier,Geneva,Switzerland,http:/www.iso.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 where:Ni=number of molecules having a specific molar mass Mi,andwi=mass of molecules having a specific mo
16、lar mass Mi.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-