【英文标准名称】:StandardTestMethodforDeterminingtheChemicalCompositionandSequenceinAlginatebyProtonNuclearMagneticResonance(1HNMR)Spectroscopy
【原文标准名称】:质子核磁共振波谱法测定褐藻酸盐中的化学成分和序列的标准试验方法
【标准号】:ASTMF2259-2010
【标准状态】:现行
【国别】:美国
【发布日期】:2010
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:F04.42
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:Alginates;Biomedicalmaterials/applications;Chemicalanalysis--chemicals;Degradation--environmentalmaterials/applications;Monomersequence;Nuclearmagneticresonance(NMR)spectrometry;Pharmaceuticalindustry;TEMPs(tissueengineeredmedicalprodu
【摘要】:Thecompositionandsequentialstructureofalginatedeterminesthefunctionalityofalginateinanapplication.Forinstance,thegellingpropertiesofanalginatearehighlydependentuponthemonomercompositionandsequentialstructureofthepolymer.Gelstrengthwilldependupontheguluronicacidcontent(FG)andalsotheaveragenumberofconsecutiveguluronatemoietiesinG-blockstructures(NG>1).Chemicalcompositionandsequentialstructureofalginatecanbedeterminedby1H-and13C-nuclearmagneticresonancespectroscopy(NMR).AgeneraldescriptionofNMRcanbefoundinx003C;761>oftheUSP24-NF19.TheNMRmethodologyandassignmentsarebasedondatapublishedbyGrasdalenetal.(1979,1981,1983).,,TheNMRtechniquehasmadeitpossibletodeterminethemonadfrequenciesFM(fractionofmannuronateunits)andFG(fractionofguluronateunits),thefournearestneighboring(diad)frequenciesFGG,FMG,FGM,FMM,andtheeightnextnearestneighboring(triad)frequenciesFGGG,FGGM,FMGG,FMGM,FMMM,FMMG,FGMM,FGMG.Knowledgeofthesefrequenciesenablesnumberaveragesofblocklengthstobecalculated.NGisthenumberaveragelengthofG-blocks,andNG>1isthenumberaveragelengthofG-blocksfromwhichsinglets(-MGM-)havebeenexcluded.Similarly,NMisthenumberaveragelengthofM-blocks,andNM>1isthenumberaveragelengthofM-blocksfromwhichsinglets(-GMG-)havebeenexcluded.13CNMRmustbeusedtodeterminetheM-centeredtriadsandNM>1.Thistestmethoddescribesonlythe1HNMRanalysisofalginate.AlginatecanbewellcharacterizedbydeterminingFGandNG>1.Inordertoobtainwell-resolvedNMRspectra,itisnecessarytoreducetheviscosityandincreasethemobilityofthemoleculesbydepolymerizationofalginatetoadegreeofpolymerizationofabout20to50.Acidhydrolysisisusedtodepolymerizethealginatesamples.Freeze-drying,followedbydissolutionin99%D2O,andanotherfreeze-dryingbeforedissolutionin99.9%D2Oyieldssampleswithlow1H2Ocontent.TTHAisusedasachelatortopreventtracesofdivalentcationstointeractwithalginate.WhileTTHAisamoreeffectivechelator,otheragentssuchasEDTAandcitratemaybeused.Suchinteractionsmayleadtolinebroadeningandselectivelossofsignalintensity.Samplesareanalyzedatatemperatureof80x00B1;1x00B0;C.Elevatedsampletemperaturecontributestoreducingsampleviscosityandrepositionstheprotonsignalofresidualwatertoanareaoutsidethatofinterest.1.1ThistestmethodcoversthedeterminationofthecompositionandmonomersequenceofalginateintendedforuseinbiomedicalandpharmaceuticalapplicationsaswellasinTissueEngineeredMedicalProducts(TEMPs)byhigh-resolutionprotonNMR(1HNMR).AguideforthecharacterizationofalginatehasbeenpublishedasGuideF2064.1.2Alginate,alinearpolymercomposedofx03B2;-D-mannuronate(M)anditsC-5epimerx03B1;-L-guluronate(G)linkedbyx03B2;-(1>4)glycosidicbonds,ischaracterizedbycalculatingparameterssuchasmannuronate/guluronate(M/G)ratio,guluronicacidcontent(G-content),andaveragelengthofblocksofconsecutiveGmonomers(thatis,NG>1