PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Gas Chromatography1. Introduction2. Stationary phases3. Retention in Gas-Liquid Chromatography4. Capillary gas-chromatography5. Sample preparation and injection6. Detectors(Chapter 2 and 3 in The essence of chromatography)Retention in Gas-Liquid ChromatographyA. General descriptorsB. retention and capacity factor: tR = tM(1+k) C. Solute retention in Binary stationary phase D. Temperature and Flow ProgrammingE. Problem solvingA. General descriptors(1) tR, tR’, and tM(2) VR, VR’, and VM(3) LR, LR’, and LM(4) VR = tR * F, and LR = tR * u(5) σV = σt * F, and σL = σt * u(6) k = tR’/ tM =the time of solute stay in mobile phasethe time of solute stay in stationary phase(7) K = k*β = k*VMVS(8) tR = tM(1+k) j = 32(Pi/P0)2-1(Pi/P0)3-1uavg = j u0 (Tc/T0) [(Po-Pw)/Po]Favg = j F0 (Tc/T0) [(Po-Pw)/Po](9) α = k1/k2 (10) Rs = (tR2-tR1)/[(Wb1+Wb2)/2] = [N1/2/4][(α -1)/(α)]*[k2/(1+ k2)],B. retention and capacity factor: tR = tM(1+k) 1. Modern methods: solute effects (Kamlet, Taft, and Abraham)System constants (c, m, r, s, a, b, and l): depended on chromatographic system conditions: mobile phase, stationary phase, and temperature. Solute descriptors (R2, π2, Σα2, Σβ2, logL, and Vx): depended on solute properties16Kamlet-Taft parameters2. Kovat’s Retention Index I = 100z +100*[logtR’(x)-logtR’(z)]/[logtR’(z+1)-logtR’(z)]Where tR’ is the adjusted retention time, z the carbon number of the n-alkane eluting immediately before the substance of interest denoted by x, and z+1 the retention number of the n-alkane eluting immediately after substance x. log k = c + rR2 + sπ2 + aΣα2 + b Σ β2 + llogLHHH16(Gas chromatography)Kovat’s approach is using retention of n-alkanes as standards to Index the retention of substance of interest on a certain chromatographic system. I = 100z +100*[logtR’(x)-logtR’(z)]/[logtR’(z+1)-logtR’(z)]3. McReynolds’ phase constantsΔI = I stationary phase x – I squaleneSqualene (C30H62)ΔI = aX’ +bY’ + cZ’ + dU’ +eS’McReynold’s phase constantsPhase constant: X’: Benzene; Y’: 1-butanol; Z’: 2-pentanone; U’: 1-nitropropane; S’: Pyridinea, b, c, d, e, constants for the solute of interest.Comparison to the method by Kamlet, Taft, and AbrahamIdea is same: use constants from systems and solute to describe retention Difference: Kamlet et al use solvatochromic parameters to index the constant of solute of interest. McReynolds uses properties of specific molecules to index constant of solute of interest.ΔI = aX’ +bY’ + cZ’ + dU’ +eS’McReynold’s phase constantsPhase constant: X’: Benzene; Y’: 1-butanol; Z’: 2-pentanone; U’: 1-nitropropane; S’: Pyridinea, b, c, d, e, constants for the solute of interest.(Gas chromatography)System constants (c, m, r, s, a, b, and l): depended on chromatographic system conditions: mobile phase, stationary phase, and temperature. Solute descriptors (R2, π2, Σα2, Σβ2, logL, and Vx): depended on solute properties16Kamlet-Taft parametersMethod by Kamlet, Taft, and AbrahamMethod by McReynoldslog k = c + rR2 + sπ2 + aΣα2 + b Σ β2 + llogLHHH16C. Solute retention in Binary stationary phase (combinatorial approach)1. Mixture of stationary phasesKs = ΦA KA + ΦB KB ΦA+ ΦB = 1Where: Ks is the gas-liquid partition coefficient for a solute on a mixed bed stationary phase. KA or Kb are the gas-liquid partition coefficients for a solute on a pure stationary phase A or B, respectively. α = k1/k2 = K1/K22. Coupled columnsColumn A Column BKs = ΦA KA + ΦB KB Ks = (PKA + KB) / (P+1) P = tMA/tMBThe essence of Chromatography: p128Rs = [N1/2/4][(α -1)/(α)]/[k2/(1+ k2)],Question: After two solutes achieve baseline separation in the first GC column, what is the consequence if let them go through the second column?D. Temperature and Flow Programming1. Temperature programming:2. Flow programming:Htot = A + B/u + Cu (van Deemter equation)Retention in Gas-Liquid ChromatographyA. General descriptorsB. retention and capacity factor: tR = tM(1+k) C. Solute retention in Binary stationary phase D. Temperature and Flow Programming13. A mixture of two solutes in injected into a 25 m X 0.2 mm ID capillary GC column using nitrogen as the carrier gas and a column temperature of 150 oC; the average flow rate of nitrogen through the column is 10 mL/min. The first solute in the injected mixture eluted with a retention time of 10.23 min and a baseline width of 0.15 min; the second solute in the mixture elutes at 10.41 min with a baseline width of 0.18 min. Injection of air (a non-retained solute) produces a peak at 0.08 min. The diffusion coefficient for both solute 1 and 2 under these conditions is roughly 1 X 10-1 cm2/sec. Please determine each of the following values for this system.(a) Separation factor α between solute 1 and 2. (b) the plate number for solute 1 and 2. (c) Is baseline resolution is achieved in this separation. (d) The average time it takes solute 1 to travel across the diameter of the GC capillary (i.e., 0.2