PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Gas Chromatography1. Introduction2. Stationary phases3. Retention in Gas-Liquid Chromatography4. Capillary gas-liquid chromatography5. Sample preparation and injection6. Detectors(Chapter 2 and 3 in The essence of chromatography)Capillary Gas-Liquid ChromatographyA. Separation efficiency and rate theoryB. Preparation of Capillary ColumnC. Evaluation of Capillary ColumncapillarypackedPacked-bed and capillary GCCapillary GC has much higher separation efficiency than packed-bed GC!Rate theory-- Van Deemter Equation(1+εp/εe)2Dmu2λ dp + qs k(1+k)2df2Dsu++dp2Dmf(k)u1. Packed-bed systemH = A + B/u + (CS + CM)uλ:column packing factor (0.5~1.5)dp: average size of the filling particlesεp: intraparticle porosityεe: interparticle porosityDm: solute diffusion coefficient in mobile phase. k: capacity factor k = K (Vs/Vm)Ds: solute diffusion coefficient in stationary phase.qs:shape factor for the stationary phase coating coating (2/3 for a thin layer). df: thickness of stationary phase2. Capillary system—open tubular system 2Dmu2k3(1+k)2df2Dsu+d2DmuH = B/u + (CS + CM)u1+6k+11k296(1+k)2+No eddy diffusion!Hmin = 2*(BC)1/2uopt = (B/C)1/2H = B/u + Cud2Dm1+6k+11k296(1+k)2Cm =2k3(1+k)2df2Dsd2Dm1+6k+11k296(1+k)2+CS + CM =H = B/u + (CS + CM)uThe ratio of CS and Cm contributions to the term of resistance to mass transfer is determined by the phase ration. (Vm/Vs) = d/4df , when, d>>dfHmin = 2*(BC)1/2uopt = (B/C)1/2The Effect of Carrier Gas H = B/u + (CS + CM)uDAB =1.00 x 10-3 T1.75P[(sum vi)A1/2 + (sum vi)B1/2] ( )MWA1MWB1DAB = kT/(6πηBrA)gasliquid2Dmu2k3(1+k)2df2Dsu+d2DmuH = B/u + (CS + CM)u1+6k+11k296(1+k)2+TudfdkParameters affecting plate heightPolymer coatingFused silica tubeCoated stationary phasePreparation of Capillary Column1. Materials a. glass: soda-lime (soft) alkalineSiO2 67.7%, Na2O 15.6%, CaO 5.7%, MgO 3.9%, Al2O3 2.8%, BaO 0.8%, and K2O 0.6% borosilicate (hard), acidic SiO2 67.7%, B2O3 13 %, Na2O 3.0%, Al2O3 2.0%, and K2O 1.% b. fused silicaSiCl4 + O2 SiO2Surface: Si—OH, O--SiH-O Silanol Siloxane2. Film Formation on Inner Surface of Tubes(A) Uniform stationary film is essential for high-efficiency separationThin, smooth, and homogeneous film(1) Surface tension (wettability): the surface tension of stationary phase should be smaller than that of glass or fused silica.(2) The stability of the film depends on the viscosity of liquid and thickness of film (surface tension). (B) Surface modification(1) Improvement of wettability of glass surface: HCl (gas)(2) Deactivation: silylation (C) Coating TechniquesDynamic coating, and Static coatingEvaluation of Column Quality1. Activity test for uncoated columns2. Grob test for coated columnsGrob TestEssence of Chromatography, Page 154Old columnNew column(1) The height of the peaks(2) The shape of the peaks3. Columns Thermal StabilityThe bleed products from stationary phase consist primarily of low molecular weight impurities. Fused silica columns show very low levels of thermally induced catalytic phase decompositionCapillary Gas-Liquid ChromatographyA. Separation efficiency and rate theoryB. Preparation of Capillary ColumnC. Evaluation of Capillary