涡流扩散项课件

《涡流扩散项课件》由会员分享，可在线阅读，更多相关《涡流扩散项课件（104页珍藏版）》请在装配图网上搜索。

1、Mobile phase&Stationary phase（流动相与固定相（流动相与固定相):Chromatographic separation involving partition of different species in a mixture in two phases,among which one phase(solid or liquid)does not move(stationary phase),the other phase(gas or liquid)takes the sample mixture to pass through the stationary ph

2、ase packed in the column(mobile phase)Separations are affected due to the differences of substances affinities for a mobile phase and a stationary phase(分离原理）.GCGas supplyFlow controllerOvenColumnTo wasteDetectorFlow meter(In one of these positions)InjectionsystemAmplifierIntegratorRecorderGC皂膜流量计转字

3、流量计调整仪，标准仪Setup of Gas ChromatographGCinert gases wothout interaction with analytes or stationary phase管状的Thermal conductivity detectorElectron capture detector,IR,FPDFlame photometric detectorHydrogen flame ionization detectorChromatogram of xylene isomers on a polar column GCYGC0124Peak width at a

4、 half heightPeak width at peak baseAdjusted retention timeRotention timeDeadtimeAir peak0.607h1/2h2Y1/2YtRtRtMInjectiontResponse signalChromatogramTime(arbitrary units)Nomenclature of Chromatographic separationChromatographic Curve&ChromatogramChromatographic Curve&Chromatogram The chart of output d

5、etector response(concentration)versus time The protuberance in the curve is called chromatographic peak 如果进样量很小，浓度很低，在吸附等温线（气固吸附色谱）或分配等温线（气液分配色谱）的线性范围内，则色谱峰是对称的。Baseline(Baseline(基线基线)Chromatographic curve under the experimental operation conditions,no components of materials flow out after the colu

6、mn(在实验操作条件下，色谱柱后没有样品组分流出时的流出曲线称为基线，反映检测器系统噪声（Noise)随时间的变化情况。稳定的基线应该是一条水平直线。)Nomenclature of Chromatographic separationBaseline drift(基线漂移）基线漂移）refer to 基线随时间定向的缓慢变化Peak height refer to Vertical distance from the vertex of chromatographic peak to baseline 色谱峰顶点与基线之间的垂直距离，以（h）表示。Nomenclature of Chroma

7、tographic separationChromatogram and chromatographic peak Baseline（a）Peak height（h）信号进样空气峰色谱峰ha色谱流出曲线Retention valueRetention value 表示试样中各组分在色谱柱中滞留时间的数值。通常用时间或用将组分带出色谱柱所需载气的体积来表示。Rely on component partition on two phases(or Rely on component partition on two phases(or absorption)absorption)Thermodyn

8、amic controlled(Properties of Thermodynamic controlled(Properties of stationary phase&operation conditions)stationary phase&operation conditions)Qualitative BaseQualitative BaseNomenclature of Chromatographic separation Dead Time tM 不被固定相吸附或溶解的物质(如空气，甲烷等）进入色谱柱时，从进样到出现峰极大值（浓度）所需的时间称为死时间，它正比于色谱柱的空隙体积。

9、见图Rotention time tRotention time tR R The time at which the maximum of the peak appears after sample injection 见图Nomenclature of Chromatographic separation 因为这种物质不被固定相吸附或溶解，故其流动速度将与流动相流动速度相近。测定流动相平均线速时，可用柱长L与tM的比值计算，即 =L/tMNomenclature of Chromatographic separationAdjusted rotention time(tR)The diff

10、erence between the rotention time and dead time 某组分的保留时间扣除死时间后，称为该组分的调整保留时间，即 tR=tR tMMore time the component spends due to dissolution in(or adsorption on)the stationary phase than inert components without interaction.保留时间是色谱法定性的基本依据，但同一组分的保留时间常受到流动相流速的影响，因此色谱工作者有时用保留体积保留体积来表示保留值。Dead Volume Dead V

11、olume VM 指色谱柱在填充后，柱管内固定相颗粒间所剩留的空间、色谱仪中管路和连接头间的空间以及检测器的空间的总和。当后两相很小可忽略不计时，死体积可由死时间与色谱柱出口的载气流速F0（cm3min-1）计算。VM =tMF0 式中 F0为扣除饱和水蒸气压并经温度校正的流速。仅适用于气相色谱，不适用于液相色谱Nomenclature of Chromatographic separationRotention volume VR 指从进样开始到被测组分在柱后出现浓度极大点时所通过的流动相的体积。保留时间与保留体积关系：VR=tR F0 =tM F0 Nomenclature of Chro

12、matographic separationVR，VR do not depend on velocity of the carrier gas.Adjusted rotention volume VR 某组分的保留体积扣除死体积后，称为该组分的调整保留体积。VR =VR VM =tR F0 The ratio of adjusted rotention value of the second component to that of the first component r21=tR(2)/tR(1)=VR(2)/VR(1)tR(2)/tR(1)VR(2)/VR(1)由于相对保留值只与柱温

13、及固定相性质有关，而与柱径、柱长、填充情况及流动相流速无关，因此，它在色谱法中，特别是在气相色谱法中，广泛用作定性的依据。Nomenclature of Chromatographic separation The higher r21,the bigger difference between the adjusted rotention values of adjacent components,the better the separation.When r21=1,the two components can not separate at all.Relative rotention

14、 value r21 在定性分析中，通常固定一个色谱峰作为标准（s），然后再求其它峰（i）对这个峰的相对保留值，此时可用符号表示，即 =tR(i)/tR (s)式中tR(i)为后出峰的调整保留时间，所以总是大于1的。相对保留值往往可作为衡量固定相选择性的指标，又称选择因子选择因子。Nomenclature of Chromatographic separation Peak width(区域宽度区域宽度)色谱峰的区域宽度是色谱流出曲线的重要参数之一，用于衡量柱效率及反映色谱操作条件的动力学因素。表示色谱峰区域宽度通常有三种方法。Standard deviation Half width of

15、chromatographic peak at 0.607 times peak height(0.607倍峰高处色谱峰宽的一半)Nomenclature of Chromatographic separationDue to easiness to measure,Y1/2 is always used to denote peak width.Peak width at half-height(半峰宽度、半峰宽度、半峰宽、半峰宽、区域宽度）区域宽度）Y1/2 即峰高一半处对应的峰宽。它与标准偏差的关系为 Y1/2=2 SQR(2ln2)=2.354 Peak width at peak b

16、ase(峰底宽度峰底宽度)Y 即色谱峰两侧拐点上的切线在基线上的截距。它与标准偏差的关系是 Y=4 从色谱流出曲线中，可以得到许多重要信息：Nomenclature of Chromatographic separationJudge the number of the components included a mixture based on the number of peaksQualitative analysis based on the rotention value of chromatographic peakQuantitative analysis based on ar

17、eas or heights of chromatographic peaks Rotention value and peak width of chromatographic peaks is the basic to evaluate separation efficiency of chromatographic column 色谱峰两峰间的距离，是评价固定相（或流动相）选择是否合适的依据。2.2 Theoretical foundation of gas chromatographic analysis2.2.1Gas solid or Gas liquid chromatograp

18、hyCapillary column（毛细管柱）（毛细管柱）:The column has internal diameter of less than one mm,and inner wall of the column is usually coated with a film of stationary liquidChromatographic columnPacked column(填充柱）填充柱）:Packed stationary usually made from metal materials(copper or stainless steel)or glass,with

19、a height of 0.5-10m and inside diameter of 2-6mm.U-shape or screwy(螺旋形）Stationary phaseGas-solid chromatography（气（气-固色谱）固色谱）:porous solid materials or adsorptive particles with higher surface areaMechanism:Adsorption&Elution(desorption)Gas-liquid chromatography（气（气-液色谱）液色谱）:Chemical inert solid part

20、icles(担体担体,support)coated with a film of organic chemical of high-boiling point（Stationary liquid,固定液）固定液）Mechanism:Dissolution&volatilization2.2 Theoretical foundation of gas chromatographic analysisPartition Coefficient(K):Concentration ratio of the component in stationary phase and mobile phase w

21、hen the partition process arrives at equilibrium under given temperature.K=Concentration of the component in stationary phaseConcentration of the component in mobile phase=cS/cMGas chromatographic analysis based on the difference of the partition coefficients of different substancesPartition Process

22、:Adsorption,elution,and dissolution,volatilization process of the substances between stationary phase and mobile phase.2.2 Theoretical foundation of gas chromatographic analysisPartition ratio(capacity factor,capacity ratio,k):Mass ratio of the component in two phases when partition process arrives

23、at equilibrium under given temperature and pressurek=mS/mMmS refers to mass of the component distributed in stationary phase,mS mass of the component distributed in mobile phaseRelationship between k and KK=cS/cM=(mS/VS)/(mM/VM)=k VM/VS=kb bVM refers to mobile phase volume in column,that is,柱内固定相颗粒间

24、的空隙(lacuna）体积。VS Stationary phase volume in column(在气-液色谱中为固定液体积，气-固色谱中为吸附剂的表面容量。Phase ratio(相比，相比，b b):VM/VS,反映各种色谱柱柱型及其结构特征Packing column:6-35,Capillary column:50-1500Stationary liquidCapillary wallStationary phaseRelationship of K and k K refers to concentration ratio and k mass ratioK and k depe

25、nds on thermodynamic properties of the components and stationary phase,Tc(柱温），Pc(柱压）K only relys on properties of the component and double phases,but not phase ratio.But k relys on not only properties of the component and double phases,but also phase ratio(amount of stationary phase)With a given chr

26、omatographic system,separation of the components is determined by relative amount of the components in both phases,but not relative concentration.The bigger k value,the longer rotention time,the easier separation.k=0 corresponds to dead time tM.Ratio of the velocity of carrier gas and the component

27、in column:Rs=uS/u=w=mM /(mS+mM)=1/(1+mS/mM)=1/(1+k)Where u refers to velocity of carrier gas in column in unit of cm.s-1,u velocity of the component in column,w mass fraction.Retardation factor(滞留因子滞留因子,Rs）：）：Defining L as column length,following formula are vivid:tR=L/uStR=L/uS=tMu/uS=tM u/uS=tM(1+

28、k)k=(tR-tM)/tM=tR/tMtM=L/uAbove equation can be employed to evaluate k value.2.2.1Basic theory of chromatographic separationPartition of different components in double phasesDepending on partition coefficient,molecular structure and properties of the components,stationary phase,mobile phase.Characte

29、rized by rotention value(rotention time or rotention volume),thermodynamic controlled.Movement of different components in columnDepending on mass transfer(传质)resistance of different components in stationary phase and mobile phase.Characterized by peak width at half-height,kinetic controlledTheoriesT

30、wo approaches can be taken to explain the separation processPlate theory proposed in 1941 by Martin and Synge.Based on an analogy with distillation and counter current extractionRate theory accounts for the dynamics of a separation 1956,J.J.Van Deemter.Each has advantages and limitations.Plate theor

31、y(塔板理论塔板理论)借用传统的蒸馏过程处理色谱过程 将色谱柱比作一个分馏塔，色谱柱由许多假想的塔板组成（即将色谱柱分成许多各小段），在每一个塔板内，一部分空间被涂在担体上的液相占据，另一部分空间则充满气相（载气），载气占据空间称为板体积DV.当欲分离的组分随载气进入色谱柱后，就在两相间进行分配。由于流动相在不停地移动，组分就在这些塔板间隔的气液两相间不断地达到分配平衡。Plate theory assumes:在一小段间隔（塔板）内，气相平均组成与液相平均组成能很快达到分配平衡。达到分配平衡的一小段柱长称为理论塔板高度H（Height equivalent to theoretical pl

32、ate)载气进入色谱柱，不是连续的，而是脉动式的，每次进气为一个板体积试样开始时都加在第0号塔板上，且试样沿色谱柱方向的扩散（纵向扩散）可忽略不计分配系数在各塔板上是常数Assuming the column consists of 5 plates,n=5(number of theoretical plates),r is defined as number of plate,r=0,1,2,n-1.With m=1,k=1,w=1/2,when carrier gas of one more plate volume enters the column pulsantly,partiti

33、on in each plate is shown as follows:Mass in mobile phaseMass in stationary phase原塔板1固定相中组分的质量（0.125+0.125=0.25)与随载气带入的原塔板0流动相中组分质量(0.125)重新分配:(0.25+0.125)/2=0.188Partition table of the component in any plate in a column with n=5,k=1 and w=1/2Total amount Total amount of the solute of the solute in

34、a platein a plateChromatogram of the component in a column with n=5,N is number of plate volume of carrier gas Peak asymmetry since n is too small Concentration maximum at N=8-9 Peak symmetry near normal distribution when n 50 n=103 106 for gas chromatographyWhen number of theoretical plates is big

35、enough,chromatogram approaches normal distribution curve,following relationship between concentration C and time t is obtained:Where C0 is injection concentration(进样浓度）,C concentration at outlet（出口）of the column at time t流出曲线方程式Relationship of n to peak width:Where L is length of chromatographic col

36、umn,tR,Y1/2,Y in the same units,n theoretical plate number,H theoretical plate height.为了扣除死时间或死体积的影响，实际工作中常用有效塔板数（Effective plate number)和有效塔板高度（Effective plate height)作为柱效能指标：n=1+k k2 n有效有效色谱柱的柱效能还与物质的性质有关，同一色谱柱的柱性能对不同物质是不同的。色谱柱的理论塔板数越大，表示组分在色谱柱中达到分配平 衡的次数越多，固定相的作用越显著，因而对分离越有利。但不 能预言并确定各组分是否有被分离的可能

37、，因为分离的可能性决定于试样混合物在固定相中分配系数的差别，而不决定于分配 次数的多少。n有效不能作为有无实现分离可能的依据，而只是在一定条件下柱分离能力发挥程度的标志。塔板理论没有考虑动力学因素的影响，因而不能解决塔板高度受什么因素影响以及流速对理论塔板数的影响等问题。（扩散）（扩散）Rate theory of chromatographyIt is based on a Gaussian distribution similar to that of plate theoryHe was attempting to account for the dynamics of the sepa

38、ration process.23H=A+CuBu0.01k2 dp2(1+k)2 Dgu+（填充的不均匀性）（填充的不均匀性）（弯曲因子）（弯曲因子）（组分在载气流中的分子扩散系数）（组分在载气流中的分子扩散系数）（固定相的液膜厚度）（固定相的液膜厚度）(涡流扩散项涡流扩散项）（分子扩散项分子扩散项）（液相传质过程液相传质过程）0.01k2 dp2(1+k)2 DguGas term(气相传质过程气相传质过程）(涡流扩散项涡流扩散项）（分子扩散项分子扩散项）（传质项传质项）涡流扩散项（涡流扩散项（vortex diffusion term)由于填充物颗粒的阻碍作用，当气体通过时，会不 断改变

39、流动方向，使样品组分在气相中形成类似“涡流”的流动，引起色谱峰的扩张。涡流扩散项的大小与填充物的平均颗粒直径dp(单位未cm)大小及填充的不均匀性有关，而与载气性质，线速度和组分无关。空心毛细管柱，涡流扩散项A为零。使用细粒度和粒度分布均匀的颗粒作为担体，且填充均匀，可以减少涡流扩散，提高柱效能。返回分子扩散项分子扩散项B/u(纵向扩散项纵向扩散项)(Longitudinal diffusion term)试样组分被载气带入色谱柱后，以“塞子”的形式存在于柱内很小一端空间中，在“塞子”的前后（纵向）存在着浓差而形成浓度梯度，使运动着的分子产生纵向扩散。纵向扩散项的大小B为：B=2g gDgg

40、为弯曲因子，表示因载体填充在柱内而引起气体扩散路径弯曲的因素。Dg 为组分在气相中的扩散系数（cm2.s-1)B B的影响因素：的影响因素：g 与填充物有关：由于固定相颗粒的存在，使分子不能自由扩散，从而使扩散程度降低。空心毛细管柱：没有填充物的阻碍，扩散程度最大，g=1 填充柱：由于填充物的阻碍，扩散路径弯曲，扩散程度降低，g 10时，对R的增加不明显，也会显著增加分析时间k的最佳范围：1 10与柱选择性的关系 越大，柱选择性越好，分离效果越好。如果两个相邻峰的选择因子足够大，则即使色谱柱的理论塔板数较小，也可以实现分离。分离度、柱效、柱选择性的关系通过上式可以计算相关指标的值L=16R2H

41、有效有效 a aa a-12=n有效有效 H有效有效例：例：设有一对物质，其=1.15,要求在某填充柱上得到完全分离，试计算至少需要多长的色谱柱？解：要实现完全分离，R1.5,故所需有效理论塔板数为：使用普通色谱柱，一般有效理论塔板高度为0.1cm,故所需柱长应为：Selection of separation conditionsSelection of separation conditions (分离操作条件的选择分离操作条件的选择)Selection of carrier gas and its flow rateSelection of column temperature(自学）P

42、roperties and amount of mixed liquid（自学）Properties and size of supports（自学）Injection time and injection amount（自学）Selection of carrier gas and its flow rateAccording to Van Deemter equation:Following equation can be obtained by differentiating above equation:实际工作中，为了缩短分析时间，常使流速稍高与最佳流速。andCombining a

43、bove equation and Van Deemter 当流速较小时，HB/u,分子扩散项(B项)就成为色谱峰扩张的主要因素，此时应采用分子量较大的载气(N2、Ar)，使组分在载气中有较小的扩散系数。而当流速较大队 HC u,传质项(C项)为控制因素，宜采用低分子量的载气(H2、He)，此 时组分在载气中有较大的扩散系数，可减小气相传质阻力，提高柱 效。选择载气时还应考虑对不同检测器的适应性。对于填充柱，N2的最佳实用线速为1012cms,H2为15 20cms,通常载气的流速习惯上用柱前的体积流速(mLmin)来表示，也可通过皂膜流量计在柱后进行测定。若色谱柱内径 为3mm，N2的流通一

44、般为4060mLmin，H2的流速为6090 mLmin。Selection of column temperature(自学）Understand how to select column temperatureProperties and amount of stationary liquid（自学）What influence does stationary liquid have,How to select?Requirement for mixed liquids,separation characterizationProperties and size of supports（自

45、学）Definition of support,requirement for support,how to select it?Injection time and injection amount（自学）How do they affect peak shape?How to select them?2-5 Detectors of GC2-5 Detectors of GC (Concentration sensitive detector&mass flow rate sensitive detector)Thermal conductivity detector(热导池检测器，热导池

46、检测器，TCD)Self-study&Exam:热导池的构造，工作原理及影响检测灵敏度的因素。Hydrogen flame ionization detector(氢火焰离子化检测器氢火焰离子化检测器,FID)氢火焰电离化检测器，简称氢焰检测器。对大多数有机化合物有很高的灵敏度，一般比热导池检测器的灵敏度高几个数量 级，能检测至ppb级(10-12g.s-1)的痕量物质，故适宜于痕量有机物的分析。结构简单，灵敏度高，响应快，稳定性好，线形范围宽（10-6）.Self-study&Exam:结构、作用原理、操作条件Electron capture detector(电子俘获检测器，电子俘获检测器

47、，ECD)ECDFlame photometric detector(火焰光度检测器，火焰光度检测器，FPD)FPD is highly sensitive and highly selective to the compounds containing sulphur,phosphor,etc.检测器检测器的性能指标检测器的性能指标Self-study&Exam检测器的灵敏度、检出限，最小检出量、响应时间、线形范围等的概念，物理意义，计算公式等。2-6 Qualitative analytical methods for GCQualitative analysis based on chr

48、omatographic rotention value直接根据色谱保留值进行定性直接根据色谱保留值进行定性各种物质在一定的色谱条件下（固定相、操作条件）均有确定的保留值，可以作为定性指标。适合于已知混合物及已确定存在范围或类型的化合物的鉴定对于完全未知的化合物鉴定，可靠性较差。方法的可靠性与色谱柱的分离效率（柱效）有密切关系常采用仅与柱温有关，而与操作条件（柱长、固定液含量、载气流速等）无关，重现性较好的相对保留值r21作为定性指标。与文献值比较与标准样对照混合进样:将标准样与未知物混合进样，通过观察是否有新峰出现，或未知峰上是否出现分叉等现象，判断未知物与标准样是否属同一物质。多柱法：通过

49、多根不同性质的色谱柱分离实验，确定标准样与未知样是否属同一物质。不同物质在同一根色谱柱上可能具有相同的保留值。保留指数法（rotention index,Kovats index)Seen in next page保留指数保留指数I：用两个紧靠近待测物质的标准物（一般选用两个相邻的正构烷烃）标定被测物质，并使用均一标度（即不用对数），用下式定义：I=100 lgXi lgXZlgXZ+1 lg XZ +ZX为保留值（tR,VR,或相应的记录纸距离），下脚标i为被测物质，Z,Z+1为正构烷烃的碳原子数，XZ Xi XZ+1，IZ=Z 100EXAMPLEFigure Sketch map for

50、 determination of rotention indexFrom the right figure,following data can be gottenZ=7n-heptane:Butyl ester acetate:n-octane:GC-MS,GC-IR,GC-chemical analysisITCABX1X22-7 Quantitative analysis of GC2-7 Quantitative analysis of GCUnder given chromatographic conditions,mass(or concentration in carrier

51、gas)of analyte is directly proportional to response signal of the detector(chromatographic peak area or height):mi=fi Ai firefers to quantitative calibration factorPeak area measurementsPeak area measurements1.Peak area equals to product of peak height and peak width at half heightA=h Y1/2上式计算得到的峰面积

52、仅为实际面积的0.94倍，实际峰面积应为：A=1.065h Y1/2不过，在相对计算时，1.065常可以忽略特点：特点：快速、简便，但不适合于不对称峰、窄峰、极弱峰。2.Product of peak height and peak width at peak base A h Y用本方法测得的峰面积约为真实面积的0.98倍。本方法适用于矮宽峰。3.Average peak width method(平均峰宽法平均峰宽法)A=h YY=(Y0.15+Y0.85)/2本方法适用于不对称峰（asymmetrical)4.Product of peak height and rotention ti

53、meUnder given operation conditions,peak width at half-height of 同系物 is proportional to rotention time:Y1/2 tRY1/2=btRA=hY1/2=bhtR相对计算时，常数b可以省略。特点：简便、快速，适用于狭窄峰，工厂控制分析。5.积分仪（积分仪（integral meter)Simple、convenient、fast、exact（precision ranges 0.2%2%)，and linear range wideQuantitative calibration factormi=

54、fi Aifi=mi/Aifi 为绝对质量校正因子，表征单位面积所代表的物质质量，由仪器的灵敏度决定，一般不易准确测定。实际工作中常用相对校正因子。通常，同一检测器对不同物质的响应值不同，相同质量的不同物质往往具有不同的峰面积，因而不能直接用峰面积来计算被测物质含量。因此需要对仪器响应值进行校正。Relative calibration factorRatio of absolute calibration factors of the analyte and standard substanceFor TCD,benzene employed as standardFor FID,n-hep

55、tane as standard Based on sought-out components units,following concepts are employed:Mass calibration factorMolar calibration factorVolume calibration factor1.Mass calibration factor fmfm=fi(m)fs(m)AsmiAims=Where I,s respectively refers to sought-out and standard substances2.Molar calibration facto

56、r fMfM=fi(M)fs(M)AsmiMsAimSMi=fmMSMi各物质的量以摩尔数计，MS,Mi分别表示被测物与标准物质的相对分子质量（摩尔质量）3.Volume calibration factor fV4.Relative response value sRatio of response values(sensitivity)of the substance i and standard sample s.When same unit is used,it is reciprocal of calibration factor.s=1/fs,f only rely on prop

57、erties of test sample,standard substance and type of detector,but not operation condition,cloumn temperature,flow rate of carrier gas,property of stationary liquid.Measurement of calibration factorAccurately weigh sought-out component and standard substance,after mixing,inject,analyze and determine

58、corres-ponding peak area,and then calculate calibration factors using above equations.Quantitative calculation methods in common use归一化法 （Normalization method)内标法 （Internal standard method)内标标准曲线法（Internal standard curve method)外标法（定量进样-标准曲线法）（External standard method)归一化法归一化法(Normalization method)W

59、hen all of the components can flow out the column and and show chromatographic peaks,the contents of all of the components could be determined by normalization method.If the sample consists of n components,and mass of each component is respectively m1,m2,mn,sum of all components m is 100%,then mass

60、fraction wi of component i can be calculated by following expression:wi=mim100%mi m1+m2+mn100%=Ai fi A1fi+A2f2+Anfn 100%mi mii100%=wi=mim100%mi m1+m2+mn100%=Ai fi A1fi+A2f2+Anfn 100%mi mii100%=If fi is mass calibration factor,then wi stands for mass fraction,and if fi is molar calibration factor,the

61、n wi molar fraction or volume fraction(for gas sample).Back内标法（内标法（Internal standard method)所以所以特点：特点：适用于仅需测定部分组分或试样中其它组分不能全部出峰的情况可消除由于操作条件变化而引起的误差，准确度高内标物质的选择：内标物质的选择：Back每次分析均需准确测量，故不适合快速控制分析内标标准曲线法（内标标准曲线法（Internal standard curve method)如果经常需要测定同一物质，可固定试样的称取量，并加入恒定量的内标物，此时fimS/fsm为一常数故：wi Ai/AS(o

62、r w)Figure Internal working graph适合于液体试样的常规分析Back外标法（定量进样外标法（定量进样-标准曲线法，标准曲线法，External standard method)所谓外标法就是应用欲测组分的纯物质来制作标准曲线。此时用欲测组分的 纯物质加稀释剂(对液体样品用溶剂稀释、气体样品用载气或空气 稀释)配成不同含量()标准溶液，取固定量标准溶液进样分析，从所得色谱图上测出响应讯号(峰面积或峰高等)、然后绘制响应 汛号(纵坐标)对百分含量(横坐标）的标准曲线。分析试样时，取和制作标淮曲线时同样量的试样(固定量进样)，测得该试样的响应讯号，由标准曲线即可查出其百

63、分含量。SignalwiAiwi当被测试样中各组分浓度变化范围不大时，可不必绘制标准曲线，而用单点校正法。即配 制一个和被测组分含量十分接近的标准溶液，定量进样，由被测组 分和外标组分峰面积比或峰高比来求被测组分的含量：wi Aws As=wi =wsAiAs由于S为标样，wS 和AS和均为已知故，令Ki=wS/AS,则：wi=Ki AiKi为组分i的单位面积质量分数校正值。单点校正法（单点校正法（Single dot calibration method)2-8 Capillary column gas chromatographySelf-studyProblems:Differences

64、 between capillary column GC and packing column GC毛细管色谱柱分为哪几种类型？毛细管柱有那些特点？2-9 2-9 characteristics and applications of GCHigh analytical efficiencyHigh selectivityHigh sensitivitySimple operationWide applicationsHigh analytical efficiency&SelevtivityBased on partition of the components on double phas

65、es time after timePacking column of 12m,n 103 Capillary column,n 106For example,simultaneously separating and analyzing a mixture including more than 100 components at one time using a a hollow capillary column.返回High sensitivityFor GC,mass sensitivity:10-11 10-13g10-6 10-10(mass fraction)of impurit

66、ies in ultra-pure gas,in monomer of polymer,and ultra-pure reagents can be detected.10-6 10-9(mass fraction)of pollutants in atmosphere can be directly detected.10-6 10-9(mass fraction)of halide,sulfide,phosphide in foods,water sample and so on.BackSimple and fast operationSeveral minutes to tens of minutes each testEasy to automationbackWide applicationsPracticable for analyzing all kinds of gas samples,volatile(or able to be transformed into volatile compound)liquid or solid samplesIncluding:O