渦流擴(kuò)散項(xiàng)課件

1、Mobile phase & Stationary phase（流動(dòng)相與固定相): 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

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

3、量計(jì)轉(zhuǎn)字流量計(jì)調(diào)整儀，標(biāo)準(zhǔn)儀Setup of Gas ChromatographGCinert gases wothout interaction with analytes or stationary phase管狀的Thermal conductivity detectorElectron capture detector, IR, FPDFlame photometric detectorHydrogen flame ionization detectorChromatogram of xylene isomers on a polar column GCYGC0124Peak widt

4、h at a half heightPeak width at peak baseAdjusted retention timeRotention timeDeadtimeAir peak0.607h1/2h2sY1/2YtRtRtMInjectiontResponse signalChromatogramTime(arbitrary units)Nomenclature of Chromatographic separationChromatographic Curve & Chromatogram The chart of output detector response (concent

5、ration) versus time The protuberance in the curve is called chromatographic peak 如果進(jìn)樣量很小，濃度很低，在吸附等溫線（氣固吸附色譜）或分配等溫線（氣液分配色譜）的線性范圍內(nèi)，則色譜峰是對(duì)稱的。Baseline(基線) Chromatographic curve under the experimental operation conditions, no components of materials flow out after the column(在實(shí)驗(yàn)操作條件下，色譜柱后沒(méi)有樣品組分流出時(shí)的流出曲線稱為

6、基線，反映檢測(cè)器系統(tǒng)噪聲（Noise) 隨時(shí)間的變化情況。穩(wěn)定的基線應(yīng)該是一條水平直線。)Nomenclature of Chromatographic separationBaseline drift(基線漂移）refer to 基線隨時(shí)間定向的緩慢變化Peak height refer to Vertical distance from the vertex of chromatographic peak to baseline 色譜峰頂點(diǎn)與基線之間的垂直距離，以（h）表示。Nomenclature of Chromatographic separationChromatogram and

7、 chromatographic peak Baseline（a） Peak height（h）信號(hào)進(jìn)樣空氣峰色譜峰ha色譜流出曲線Retention value 表示試樣中各組分在色譜柱中滯留時(shí)間的數(shù)值。通常用時(shí)間或用將組分帶出色譜柱所需載氣的體積來(lái)表示。 Rely on component partition on two phases (or absorption) Thermodynamic controlled (Properties of stationary phase & operation conditions) Qualitative BaseNomenclature of

8、 Chromatographic separation Dead Time tM 不被固定相吸附或溶解的物質(zhì)(如空氣，甲烷等）進(jìn)入色譜柱時(shí)，從進(jìn)樣到出現(xiàn)峰極大值（濃度）所需的時(shí)間稱為死時(shí)間，它正比于色譜柱的空隙體積。見(jiàn)圖Rotention time tR The time at which the maximum of the peak appears after sample injection 見(jiàn)圖Nomenclature of Chromatographic separation 因?yàn)檫@種物質(zhì)不被固定相吸附或溶解，故其流動(dòng)速度將與流動(dòng)相流動(dòng)速度相近。測(cè)定流動(dòng)相平均線速時(shí)，可用柱長(zhǎng)L與tM

9、的比值計(jì)算，即 = L/tMNomenclature of Chromatographic separationAdjusted rotention time(tR) The difference between the rotention time and dead time 某組分的保留時(shí)間扣除死時(shí)間后，稱為該組分的調(diào)整保留時(shí)間，即 tR= tR tMMore time the component spends due to dissolution in (or adsorption on) the stationary phase than inert components withou

10、t interaction.保留時(shí)間是色譜法定性的基本依據(jù)，但同一組分的保留時(shí)間常受到流動(dòng)相流速的影響，因此色譜工作者有時(shí)用保留體積來(lái)表示保留值。Dead Volume VM 指色譜柱在填充后，柱管內(nèi)固定相顆粒間所剩留的空間、色譜儀中管路和連接頭間的空間以及檢測(cè)器的空間的總和。當(dāng)后兩相很小可忽略不計(jì)時(shí)，死體積可由死時(shí)間與色譜柱出口的載氣流速F0（cm3min-1）計(jì)算。 VM = tMF0 式中 F0為扣除飽和水蒸氣壓并經(jīng)溫度校正的流速。僅適用于氣相色譜，不適用于液相色譜Nomenclature of Chromatographic separationRotention volume VR

11、指從進(jìn)樣開(kāi)始到被測(cè)組分在柱后出現(xiàn)濃度極大點(diǎn)時(shí)所通過(guò)的流動(dòng)相的體積。保留時(shí)間與保留體積關(guān)系： VR= tR F0 = tM F0 Nomenclature of Chromatographic separationVR， VR do not depend on velocity of the carrier gas.Adjusted rotention volume VR 某組分的保留體積扣除死體積后，稱為該組分的調(diào)整保留體積。 VR = VR VM = tR F0 The ratio of adjusted rotention value of the second component to

12、that of the first component r21= tR(2) / tR(1)= VR(2) / VR(1) tR(2) / tR(1) VR(2) / VR(1) 由于相對(duì)保留值只與柱溫及固定相性質(zhì)有關(guān)，而與柱徑、柱長(zhǎng)、填充情況及流動(dòng)相流速無(wú)關(guān)，因此，它在色譜法中，特別是在氣相色譜法中，廣泛用作定性的依據(jù)。Nomenclature of Chromatographic separation The higher r21 , the bigger difference between the adjusted rotention values of adjacent compon

13、ents , the better the separation. When r21=1, the two components can not separate at all.Relative rotention value r21 在定性分析中，通常固定一個(gè)色譜峰作為標(biāo)準(zhǔn)（s），然后再求其它峰（i）對(duì)這個(gè)峰的相對(duì)保留值，此時(shí)可用符號(hào)表示，即 = tR (i) / tR (s) 式中tR (i)為后出峰的調(diào)整保留時(shí)間，所以總是大于1的。相對(duì)保留值往往可作為衡量固定相選擇性的指標(biāo)，又稱選擇因子。Nomenclature of Chromatographic separation Peak wi

14、dth(區(qū)域?qū)挾? 色譜峰的區(qū)域?qū)挾仁巧V流出曲線的重要參數(shù)之一，用于衡量柱效率及反映色譜操作條件的動(dòng)力學(xué)因素。表示色譜峰區(qū)域?qū)挾韧ǔＳ腥N方法。 Standard deviation Half width of chromatographic peak at 0.607 times peak height (0.607倍峰高處色譜峰寬的一半)Nomenclature of Chromatographic separationDue to easiness to measure, Y1/2 is always used to denote peak width. Peak width at h

15、alf-height(半峰寬度、半峰寬、區(qū)域?qū)挾龋℡1/2 即峰高一半處對(duì)應(yīng)的峰寬。它與標(biāo)準(zhǔn)偏差的關(guān)系為 Y1/2=2s SQR(2ln2)=2.354Peak width at peak base(峰底寬度) Y 即色譜峰兩側(cè)拐點(diǎn)上的切線在基線上的截距。它與標(biāo)準(zhǔn)偏差的關(guān)系是 Y = 4 從色譜流出曲線中，可以得到許多重要信息：Nomenclature of Chromatographic separationJudge the number of the components included a mixture based on the number of peaksQualitative

16、 analysis based on the rotention value of chromatographic peakQuantitative analysis based on areas or heights of chromatographic peaks Rotention value and peak width of chromatographic peaks is the basic to evaluate separation efficiency of chromatographic column 色譜峰兩峰間的距離，是評(píng)價(jià)固定相（或流動(dòng)相）選擇是否合適的依據(jù)。2.2

17、Theoretical foundation of gas chromatographic analysis2.2.1Gas solid or Gas liquid chromatographyCapillary column（毛細(xì)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）: Pack

18、ed stationary usually made from metal materials (copper or stainless steel) or glass, with a height of 0.5-10m and inside diameter of 2-6mm. U-shape or screwy(螺旋形）Stationary phaseGas-solid chromatography（氣-固色譜）: porous solid materials or adsorptive particles with higher surface areaMechanism: Adsorp

19、tion & Elution (desorption) Gas-liquid chromatography（氣-液色譜）: Chemical inert solid particles(擔(dān)體, support) coated with a film of organic chemical of high-boiling point（Stationary liquid,固定液）Mechanism: Dissolution & volatilization2.2 Theoretical foundation of gas chromatographic analysisPartition Coef

20、ficient(K): Concentration ratio of the component in stationary phase and mobile phase when 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 base

21、d on the difference of the partition coefficients of different substancesPartition Process: 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 fac

22、tor, capacity ratio, k): Mass ratio of the component in two phases when partition process arrives 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

23、 k and KK = cS/cM= (mS/VS) / (mM / VM) =k VM/ VS = kbVM refers to mobile phase volume in column, that is,柱內(nèi)固定相顆粒間的空隙 (lacuna）體積 。VS Stationary phase volume in column (在氣-液色譜中為固定液體積，氣-固色譜中為吸附劑的表面容量。Phase ratio(相比，b): VM / VS, 反映各種色譜柱柱型及其結(jié)構(gòu)特征Packing column: 6-35, Capillary column: 50-1500Stationary li

24、quidCapillary wallStationary phaseRelationship of K and k K refers to concentration ratio and k mass ratioK and k depends on thermodynamic properties of the components and stationary phase, Tc(柱溫），Pc(柱壓） K only relys on properties of the component and double phases, but not phase ratio. But k relys

25、on not only properties of the component and double phases, but also phase ratio( amount of stationary phase) With a given chromatographic 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 lon

26、ger rotention time, the easier separation. k =0 corresponds to dead time tM.Ratio of the velocity of carrier gas and the component 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 c

27、olumn, w mass fraction.Retardation factor(滯留因子, Rs）：Defining L as column length, following formula are vivid:tR = L / uStR = L /uS = tMu /uS = tM u / uS = tM(1+k)k = (tR-tM) / tM = tR / tMtM = L / uAbove equation can be employed to evaluate k value.2.2.1Basic theory of chromatographic separationPart

28、ition of different components in double phasesDepending on partition coefficient, molecular structure and properties of the components, stationary phase, mobile phase. Characterized by rotention value (rotention time or rotention volume), thermodynamic controlled.Movement of different components in

29、columnDepending on mass transfer(傳質(zhì)) resistance of different components in stationary phase and mobile phase.Characterized by peak width at half-height, kinetic controlledTheoriesTwo approaches can be taken to explain the separation processPlate theory proposed in 1941 by Martin and Synge. Based on

30、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 theory(塔板理論)借用傳統(tǒng)的蒸餾過(guò)程處理色譜過(guò)程 將色譜柱比作一個(gè)分餾塔，色譜柱由許多假想的塔板組成（即將色譜柱分成許多各小段），在每一個(gè)塔板內(nèi)，一部分空間被涂在擔(dān)體上的液相占據(jù)，另一部分空間則充滿氣相（載氣），載氣占據(jù)空間稱為板體積D

31、V.當(dāng)欲分離的組分隨載氣進(jìn)入色譜柱后，就在兩相間進(jìn)行分配。由于流動(dòng)相在不停地移動(dòng)，組分就在這些塔板間隔的氣液兩相間不斷地達(dá)到分配平衡。 Plate theory assumes:在一小段間隔（塔板）內(nèi)，氣相平均組成與液相平均組成能很快達(dá)到分配平衡。達(dá)到分配平衡的一小段柱長(zhǎng)稱為理論塔板高度H（Height equivalent to theoretical plate)載氣進(jìn)入色譜柱，不是連續(xù)的，而是脈動(dòng)式的，每次進(jìn)氣為一個(gè)板體積試樣開(kāi)始時(shí)都加在第0號(hào)塔板上，且試樣沿色譜柱方向的擴(kuò)散（縱向擴(kuò)散）可忽略不計(jì)分配系數(shù)在各塔板上是常數(shù)Assuming the column consists of 5

32、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, partition in each plate is shown as follows: Mass in mobile phaseMass in stationary phase原塔板1固定相中組分的質(zhì)量（0.125+0.1

33、25=0.25)與隨載氣帶入的原塔板0流動(dòng)相中組分質(zhì)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 of the solute in 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 to

34、o 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 enough, chromatogram approaches normal distribution curve, following relationship between concentration C and time t is obtained:Where C0

35、is injection concentration(進(jìn)樣濃度）, C concentration at outlet（出口） of the column at time t流出曲線方程式Relationship of n to peak width:Where L is length of chromatographic column, tR, Y1/2, Y in the same units, n theoretical plate number, H theoretical plate height.為了扣除死時(shí)間或死體積的影響，實(shí)際工作中常用有效塔板數(shù)（Effective plate

36、 number) 和有效塔板高度（Effective plate height)作為柱效能指標(biāo)：n = 1+k k2 n有效色譜柱的柱效能還與物質(zhì)的性質(zhì)有關(guān)，同一色譜柱的柱性能對(duì)不同物質(zhì)是不同的。色譜柱的理論塔板數(shù)越大，表示組分在色譜柱中達(dá)到分配平 衡的次數(shù)越多，固定相的作用越顯著，因而對(duì)分離越有利。但不 能預(yù)言并確定各組分是否有被分離的可能，因?yàn)榉蛛x的可能性決定于試樣混合物在固定相中分配系數(shù)的差別，而不決定于分配 次數(shù)的多少。n有效不能作為有無(wú)實(shí)現(xiàn)分離可能的依據(jù)，而只是在一定條件下柱分離能力發(fā)揮程度的標(biāo)志。塔板理論沒(méi)有考慮動(dòng)力學(xué)因素的影響，因而不能解決塔板高度受什么因素影響以及流速對(duì)理論塔板

37、數(shù)的影響等問(wèn)題。（擴(kuò)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 separation process.23H = A + +CuBu0.01k2 dp2(1+k)2 Dgu+（填充的不均勻性）（彎曲因子）（組分在載氣流中的分子擴(kuò)散系數(shù)）（固定相的液膜厚度）(渦流擴(kuò)散項(xiàng)）（分子擴(kuò)散項(xiàng)）（液相傳質(zhì)過(guò)程）0.01k2 dp2(1+k)2 D

38、guGas term(氣相傳質(zhì)過(guò)程）(渦流擴(kuò)散項(xiàng)）（分子擴(kuò)散項(xiàng)）（傳質(zhì)項(xiàng)）渦流擴(kuò)散項(xiàng)（vortex diffusion term)由于填充物顆粒的阻礙作用，當(dāng)氣體通過(guò)時(shí)，會(huì)不 斷改變流動(dòng)方向，使樣品組分在氣相中形成類似“渦流”的流動(dòng)，引起色譜峰的擴(kuò)張。渦流擴(kuò)散項(xiàng)的大小與填充物的平均顆粒直徑dp(單位未cm)大小及填充的不均勻性有關(guān)，而與載氣性質(zhì)，線速度和組分無(wú)關(guān)。空心毛細(xì)管柱，渦流擴(kuò)散項(xiàng)A為零。使用細(xì)粒度和粒度分布均勻的顆粒作為擔(dān)體，且填充均勻，可以減少渦流擴(kuò)散，提高柱效能。返回分子擴(kuò)散項(xiàng)B/u(縱向擴(kuò)散項(xiàng))(Longitudinal diffusion term)試樣組分被載氣帶入色譜柱后，

39、以“塞子”的形式存在于柱內(nèi)很小一端空間中，在“塞子”的前后（縱向）存在著濃差而形成濃度梯度，使運(yùn)動(dòng)著的分子產(chǎn)生縱向擴(kuò)散?？v向擴(kuò)散項(xiàng)的大小B為：B=2gDgg 為彎曲因子，表示因載體填充在柱內(nèi)而引起氣體擴(kuò)散路徑彎曲的因素。Dg 為組分在氣相中的擴(kuò)散系數(shù)（cm2.s-1)B的影響因素： g 與填充物有關(guān)：由于固定相顆粒的存在，使分子不能自由擴(kuò)散，從而使擴(kuò)散程度降低。 空心毛細(xì)管柱：沒(méi)有填充物的阻礙，擴(kuò)散程度最大，g = 1 填充柱：由于填充物的阻礙，擴(kuò)散路徑彎曲，擴(kuò)散程度降低，g 10時(shí)，對(duì)R的增加不明顯，也會(huì)顯著增加分析時(shí)間k的最佳范圍：1 10與柱選擇性的關(guān)系a 越大，柱選擇性越好，分離效果越

40、好。如果兩個(gè)相鄰峰的選擇因子足夠大，則即使色譜柱的理論塔板數(shù)較小，也可以實(shí)現(xiàn)分離。 分離度、柱效、柱選擇性的關(guān)系通過(guò)上式可以計(jì)算相關(guān)指標(biāo)的值L = 16R2H有效 aa-12= n有效 H有效例：設(shè)有一對(duì)物質(zhì)，其a=1.15,要求在某填充柱上得到完全分離，試計(jì)算至少需要多長(zhǎng)的色譜柱？解：要實(shí)現(xiàn)完全分離，R1.5,故所需有效理論塔板數(shù)為：使用普通色譜柱，一般有效理論塔板高度為0.1cm,故所需柱長(zhǎng)應(yīng)為：Selection of separation conditions (分離操作條件的選擇)Selection of carrier gas and its flow rateSelection

41、of column temperature(自學(xué)）Properties and amount of mixed liquid（自學(xué)）Properties and size of supports（自學(xué)）Injection time and injection amount（自學(xué)）Selection of carrier gas and its flow rateAccording to Van Deemter equation:Following equation can be obtained by differentiating above equation: 實(shí)際工作中，為了縮短分析時(shí)間

42、，常使流速稍高與最佳流速。andCombining above equation and Van Deemter 當(dāng)流速較小時(shí)，HB/u,分子擴(kuò)散項(xiàng)(B項(xiàng)) 就成為色譜峰擴(kuò)張的主要因素，此時(shí)應(yīng)采用分子量較大的載氣 (N2、Ar)，使組分在載氣中有較小的擴(kuò)散系數(shù)。而當(dāng)流速較大隊(duì) HC u,傳質(zhì)項(xiàng)(C項(xiàng))為控制因素，宜采用低分子量的載氣(H2、He)，此 時(shí)組分在載氣中有較大的擴(kuò)散系數(shù)，可減小氣相傳質(zhì)阻力，提高柱 效。選擇載氣時(shí)還應(yīng)考慮對(duì)不同檢測(cè)器的適應(yīng)性。 對(duì)于填充柱，N2的最佳實(shí)用線速為1012cms, H2為15 20cms, 通常載氣的流速習(xí)慣上用柱前的體積流速(mLmin) 來(lái)表示，也可

43、通過(guò)皂膜流量計(jì)在柱后進(jìn)行測(cè)定。若色譜柱內(nèi)徑 為3mm，N2的流通一般為4060mLmin，H2的流速為6090 mLmin。 Selection of column temperature(自學(xué)） Understand how to select column temperatureProperties and amount of stationary liquid（自學(xué)）What influence does stationary liquid have, How to select?Requirement for mixed liquids, separation characteriza

44、tionProperties and size of supports（自學(xué)）Definition of support, requirement for support, how to select it?Injection time and injection amount（自學(xué)）How do they affect peak shape? How to select them?2-5 Detectors of GC (Concentration sensitive detector & mass flow rate sensitive detector)Thermal conductiv

45、ity detector(熱導(dǎo)池檢測(cè)器，TCD)Self-study & Exam: 熱導(dǎo)池的構(gòu)造，工作原理及影響檢測(cè)靈敏度的因素。Hydrogen flame ionization detector(氫火焰離子化檢測(cè)器,FID)氫火焰電離化檢測(cè)器，簡(jiǎn)稱氫焰檢測(cè)器。對(duì)大多數(shù)有機(jī)化合物有很高的靈敏度，一般比熱導(dǎo)池檢測(cè)器的靈敏度高幾個(gè)數(shù)量 級(jí)，能檢測(cè)至ppb級(jí)(10-12g.s-1)的痕量物質(zhì)，故適宜于痕量有機(jī)物的分析。結(jié)構(gòu)簡(jiǎn)單，靈敏度高，響應(yīng)快， 穩(wěn)定性好，線形范圍寬（10-6）. Self-study & Exam: 結(jié)構(gòu)、作用原理、操作條件Electron capture detector(

46、電子俘獲檢測(cè)器，ECD)ECDFlame photometric detector(火焰光度檢測(cè)器，F(xiàn)PD)FPD is highly sensitive and highly selective to the compounds containing sulphur, phosphor, etc.檢測(cè)器檢測(cè)器的性能指標(biāo)Self-study & Exam檢測(cè)器的靈敏度、檢出限，最小檢出量、響應(yīng)時(shí)間、線形范圍等的概念，物理意義，計(jì)算公式等。2-6 Qualitative analytical methods for GCQualitative analysis based on chromato

47、graphic rotention value直接根據(jù)色譜保留值進(jìn)行定性各種物質(zhì)在一定的色譜條件下（固定相、操作條件）均有確定的保留值，可以作為定性指標(biāo)。適合于已知混合物及已確定存在范圍或類型的化合物的鑒定對(duì)于完全未知的化合物鑒定，可靠性較差。方法的可靠性與色譜柱的分離效率（柱效）有密切關(guān)系常采用僅與柱溫有關(guān)，而與操作條件（柱長(zhǎng)、固定液含量、載氣流速等）無(wú)關(guān)，重現(xiàn)性較好的相對(duì)保留值r21作為定性指標(biāo)。與文獻(xiàn)值比較與標(biāo)準(zhǔn)樣對(duì)照混合進(jìn)樣: 將標(biāo)準(zhǔn)樣與未知物混合進(jìn)樣，通過(guò)觀察是否有新峰出現(xiàn)，或未知峰上是否出現(xiàn)分叉等現(xiàn)象，判斷未知物與標(biāo)準(zhǔn)樣是否屬同一物質(zhì)。多柱法：通過(guò)多根不同性質(zhì)的色譜柱分離實(shí)驗(yàn)，確定

48、標(biāo)準(zhǔn)樣與未知樣是否屬同一物質(zhì)。不同物質(zhì)在同一根色譜柱上可能具有相同的保留值。保留指數(shù)法（rotention index, Kovats index)Seen in next page保留指數(shù)I：用兩個(gè)緊靠近待測(cè)物質(zhì)的標(biāo)準(zhǔn)物（一般選用兩個(gè)相鄰的正構(gòu)烷烴）標(biāo)定被測(cè)物質(zhì)，并使用均一標(biāo)度（即不用對(duì)數(shù)），用下式定義：I = 100 lgXi lgXZlgXZ+1 lg XZ + ZX為保留值（tR, VR,或相應(yīng)的記錄紙距離），下腳標(biāo)i為被測(cè)物質(zhì)，Z, Z+1為正構(gòu)烷烴的碳原子數(shù)，XZ Xi XZ+1，IZ = Z 100EXAMPLEFigure Sketch map for determinatio

49、n 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 GCUnder given chromatographic conditions, mass( or concentration in carrier gas) of analyte is directly proportion

50、al to response signal of the detector (chromatographic peak area or height):mi = fi Ai firefers to quantitative calibration factorPeak area measurements1. Peak area equals to product of peak height and peak width at half heightA = h Y1/2上式計(jì)算得到的峰面積僅為實(shí)際面積的0.94倍，實(shí)際峰面積應(yīng)為：A = 1.065h Y1/2不過(guò)，在相對(duì)計(jì)算時(shí)，1.065?？?/p>

51、以忽略特點(diǎn)：快速、簡(jiǎn)便，但不適合于不對(duì)稱峰、窄峰、極弱峰。2. Product of peak height and peak width at peak base A h Y用本方法測(cè)得的峰面積約為真實(shí)面積的0.98倍。本方法適用于矮寬峰。3.Average peak width method(平均峰寬法)A = h YY = (Y0.15 + Y0.85) /2本方法適用于不對(duì)稱峰（asymmetrical)4.Product of peak height and rotention timeUnder given operation conditions, peak width at h

52、alf-height of 同系物 is proportional to rotention time:Y1/2 tRY1/2 =btRA = hY1/2 = bhtR相對(duì)計(jì)算時(shí)，常數(shù)b可以省略。特點(diǎn)：簡(jiǎn)便、快速，適用于狹窄峰，工廠控制分析。5.積分儀（integral meter)Simple、convenient、fast、exact（precision ranges 0.2% 2%)，and linear range wideQuantitative calibration factormi = fi Aifi = mi / Aifi 為絕對(duì)質(zhì)量校正因子，表征單位面積所代表的物質(zhì)質(zhì)量，由

53、儀器的靈敏度決定，一般不易準(zhǔn)確測(cè)定。實(shí)際工作中常用相對(duì)校正因子。通常，同一檢測(cè)器對(duì)不同物質(zhì)的響應(yīng)值不同，相同質(zhì)量的不同物質(zhì)往往具有不同的峰面積，因而不能直接用峰面積來(lái)計(jì)算被測(cè)物質(zhì)含量。因此需要對(duì)儀器響應(yīng)值進(jìn)行校正。Relative calibration factorRatio of absolute calibration factors of the analyte and standard substanceFor TCD, benzene employed as standardFor FID, n-heptane as standard Based on sought-out com

54、ponents 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 factor fMfM =fi(M)fs(M)AsmiMsAimSMi= fmMSM

55、i各物質(zhì)的量以摩爾數(shù)計(jì)，MS,Mi分別表示被測(cè)物與標(biāo)準(zhǔn)物質(zhì)的相對(duì)分子質(zhì)量（摩爾質(zhì)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 properties of test sample, sta

56、ndard 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 corres-ponding pea

57、k area, and then calculate calibration factors using above equations.Quantitative calculation methods in common use歸一化法 （Normalization method)內(nèi)標(biāo)法 （Internal standard method)內(nèi)標(biāo)標(biāo)準(zhǔn)曲線法（Internal standard curve method)外標(biāo)法（定量進(jìn)樣-標(biāo)準(zhǔn)曲線法） （External standard method) 歸一化法(Normalization method)When all of the comp

58、onents 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 fraction wi of

59、 component i can be calculated by following expression: wi= mim100% mi m1+m2+mn100%= Ai fi A1fi + A2f2 + + Anfn 100% mimii100%=wi= mim100% mi m1+m2+mn100%= Ai fi A1fi + A2f2 + + Anfn 100% mimii100%=If fi is mass calibration factor, then wi stands for mass fraction, and if fi is molar calibration factor, then wi molar fraction or volume fraction (for gas sample).Back內(nèi)標(biāo)法（Internal standard method)所以特點(diǎn)：適用于僅需測(cè)定部分組分或試樣中其它組分不能全部出峰的情況可消除由于操作條件變化而引起的誤差，準(zhǔn)確度高內(nèi)標(biāo)物質(zhì)的選擇：Back每次分析均需準(zhǔn)確測(cè)量，故不適合快速控制分析內(nèi)標(biāo)標(biāo)準(zhǔn)曲線法（Internal standard curve method)如果經(jīng)常需要測(cè)定同一物質(zhì)，可