(6.10)--5.10分离操作条件的选择.ppt

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1、Chapter 5 Gas Chromatography5.10 Selection of separation operating conditionsThe separation degree R is the total separation efficiency index of chromatographic column.The longer the distance between the two peaks is,the narrower the separation degree R is.The larger the R value,the more complete th

2、e separation of the two adjacent components.R=1.5,the separation degree of the two adjacent components was 99.7%.R=1.0,the separation degree of the two adjacent components was 98%.R 1.5 is usually used as an index for the complete separation of adjacent two peaks.1、Separation degreeFeeding samplesTy

3、pe of carrier gas and flow rateTCD,hydrogen gas as carrier gas;FID,nitrogen gas as carrier gas;Packed columnThe best practical linear velocity is 10 14 cmcms s-1-1(nitrogen is carrier gas)15 25 cmcms s-1-1(hydrogen is carrier gas)Capillary column:The best practical linear velocity is 20 30 cmcms s-1

4、-1(nitrogen is carrier gas)30 40 cmcms s-1-1(hydrogen is carrier gas)2.Selection of separation operating conditionsAdsorbent Selection of stationary phase(solid adsorbent)Used for separation of permanent gases and small molecular hydrocarbons.Molecular sieve(polarity),silica gel(polarity),alumina(we

5、ak polarity),activated carbon(non-polarity),polymer porous spheres(non-polarity to strong polarity)2.Selection of separation operating conditions Selection of stationary phase(stationary fluid)Low melting point and high boiling point organic matter(Dinonyl phthalate,analysis of benzene,toluene,xylen

6、e mixture)Carrier bearing fixative2.Selection of separation operating conditionsClassification of fixative:It is generally classified according to the relative polarity of the fixed solutionIt is generally classified according to the relative polarity of the fixed solution The The relative relative

7、polarity polarity P P was was specified specified as as P=P=0 0 for for squalane squalane and and P=100 P=100 for for,-oxydipropionitrile,-oxydipropionitrile,and the relative polarity P was measured for the other fixatives as the standard.and the relative polarity P was measured for the other fixati

8、ves as the standard.P P is is between between 0 0 and and 100100,each each 20 20 units units are are first first order,order,the the polarity polarity is is divided divided into into 5 5 levels:levels:0,+10,+1(non-(non-polarity);polarity);+2,+3+2,+3(middle polarity);+(middle polarity);+4,+54,+5(stro

9、ng polarity).(strong polarity).Carrier(stretcher)Diatomaceous earthRed diatomaceous earthHigh-temperature calcination（Fe2O3）Analyze non-polar or weakly polar substancesWhite diatomaceous earthCalcined with Na2CO3(sodium iron silicate)Analyze polar substancesNon-diatomaceous earthFluorine carrierAnal

10、yze corrosive gasesGlass microspheresAnalysis of high boiling point substancesPolymer porous microspheres（GDX）Analyze trace water in organic matter Selection of column temperatureCannot be higher than the maximum use temperature of the fixative to prevent the loss of the fixative.It should not be lo

11、wer than the lowest operating temperature to prevent sample from condensing in the chromatographic column.The selection principle of column temperature is to make the most difficult separation of the substance on the premise of complete separation,to take lower column temperature.In the analysis,the

12、 initial column temperature was selected according to the empirical value for different samples,and then adjusted according to the experimental results.2.Selection of separation operating conditions Vapor chamber temperature and detector temperatureThe temperature of the gasifier is 50100,higher tha

13、n that of the columnThe detector temperature is generally 50,higher than the highest boiling point2.Selection of separation operating conditionsBroadening of peaks due to large injection volumeThe sample volume is too small for low content components to be detectedFor column length 2 m internal diam

14、eter 3 mm fixed liquid 15%filled column Liquid sample size is usually 0.15 L Gas injection volume 0.110 mL.Sample volume and injection technique2.Selection of separation operating conditionsMicroinjectorFig.5-45 injection position of micro injectorInjection PortComplete the Complete the explanationexplanationThank you.Thank you.