基本信息
标准名称: | 食品安全国家标准 食品中水分的测定 |
英文名称: | National food safety standard Determination of moisture in foods |
中标分类: |
食品 >>
食品综合 >>
基础标准与通用方法 |
替代情况: | 替代GB/T 5009.3-2003;GB/T 14769-1993 |
发布部门: | 中华人民共和国卫生部 |
发布日期: | 2010-03-26 |
实施日期: | 2010-06-01 |
首发日期: | |
作废日期: | |
出版社: | 中国标准出版社 |
出版日期: | |
页数: | 12页 |
适用范围
本标准规定了食品中水分的测定方法。
本标准中直接干燥法适用于在101℃~105℃下,不含或含其他挥发性物质甚微的谷物及其制品、水产品、豆制品、乳制品、肉制品及卤菜制品等食品中水分的测定,不适用于水分含量小于0.5 g/100 g的样品。
减压干燥法适用于糖、味精等易分解的食品中水分的测定,不适用于添加了其它原料的糖果,如奶糖、软糖等试样测定,同时该法不适用于水分含量小于0.5 g/100g的样品。
蒸馏法适用于含较多挥发性物质的食品如油脂、香辛料等水分的测定,不适用于水分含量小于1g/100g的样品。
卡尔.费休法适用于食品中水分的测定,卡尔.费休容量法适用于水分含量大于1.0×10-3 g/100g的样品,卡尔.费休库伦法适用于水分含量大于1.0×10-5 g/100g的样品。
前言
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目录
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引用标准
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所属分类: 食品 食品综合 基础标准与通用方法
【英文标准名称】:StandardTestMethodforDeterminationofWeight-AverageMolecularWeightofPolymersByLightScattering
【原文标准名称】:用低扩散法测定聚合物分子量和平均分子量的标准试验方法
【标准号】:ASTMD4001-1993(2006)
【标准状态】:现行
【国别】:
【发布日期】:1993
【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】:D20.70
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:高聚物;塑料;测定;工艺;分子量
【英文主题词】:lightscattering;polymers;weight-averagemolecularweight
【摘要】:Theweight-averagemolecularweightisafundamentalstructureparameterofpolymers,whichisrelatedtomanyphysicalpropertiesofthebulkmaterial,suchasitsrheologicalbehavior.Inaddition,knowledgeoftheweight-averagemolecularweight,togetherwithknowledgeofthenumber-averagemolecularweightfromosmometry,providesausefulmeasureofthebreadthofthemolecular-weightdistribution.Otherimportantusesofinformationontheweight-averagemolecularweightarecorrelationwithdilute-solutionormelt-viscositymeasurementsandcalibrationofmolecular-weightstandardsforuseinliquid-exclusion(gel-permeation)chromatography.Totheextentthatthelight-scatteringphotometerisappropriatelycalibrated,lightscatteringisanabsolutemethodandmaythereforebeappliedtononionichomopolymersthathavenotpreviouslybeensynthesizedorstudied.1.1Thistestmethoddescribesthetestproceduresfordeterminingtheweight-averagemolecularweightMwofpolymersbylightscattering.Itisapplicabletoallnonionichomopolymers(linearorbranched)thatdissolvecompletelywithoutreactionordegradationtoformstablesolutions.Copolymersandpolyelectrolytesarenotwithinitsscope.Theprocedurealsoallowsthedeterminationofthesecondvirialcoefficient,A2,whichisameasureofpolymer-solventinteractions,andtheroot-mean-squareradiusofgyration(s2)1/2,whichisameasureofthedimensionsofthepolymerchain.1.2Themolecular-weightrangeforlightscatteringis,tosomeextent,determinedbythesizeofthedissolvedpolymermoleculesandtherefractiveindicesofsolventandpolymer.Arangefrequentlystatedis10,000to10,000,000,butthismaybeextendedineitherdirectionwithsuitablesystemsandbytheuseofspecialtechniques.1.2.1Thelowerlimittomolecularweightresultsfromlowlevelsofexcesssolutionscatteringoverthatofthesolvent.Thegreaterthespecificrefractiveincrementdn/dc(differenceinrefractiveindicesofsolutionandsolventperunitconcentration),thegreaterthelevelofsolutionscatteringandthelowerthemolecularweightthatcanbedeterminedwithagivenprecision.1.2.2Theupperlimittomolecularweightresultsfromtheangulardependenceofthesolutionscattering,whichisdeterminedbythemolecularsize.Forsufficientlylargemolecules,measurementsmustbemadeatsmallscatteringangles,whichareultimatelyoutsidetherangeofthephotometerused.1.3ThevaluesstatedinSIunitsaretoberegardedasstandard.Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.TherearenosimilarorequivalentISOstandards.
【中国标准分类号】:G31
【国际标准分类号】:83_080_01
【页数】:12P.;A4
【正文语种】: