NB = HA = HB 1.5199 ×104 4.8796 x10 -4 1.973 x10-3 The number of theoretical plates for the column is calculated as N = N. X NB A Using NĄ and NB, calculate the expected resolution for this separation. resolution: mm mm Consider a separation performed on a 30.0 mm long open tubular column with a 0.50 mm diameter and a 2.0 µm thick stationary phase. Compound A eluted at 12.63 min, compound B eluted at 13.24 min, and the unretained solvent eluted at 1.205 min. What are the adjusted retention times, t, and retention factors, k, for compounds A and B? TRA tR.B KA KB = = α = 11.425 12.035 NA = 9.481 What is the separation factor (relative retention), a, for this separation? 9.987 1.053 The widths at half-height, w₁/2, of the peaks for compounds A and B are 0.120 min and 0.253 min, respectively. Find the number of theoretical plates, N, and plate height, H, for each compound. 6.1480 x104 min min

NB = HA = HB 1.5199 ×104 4.8796 x10 -4 1.973 x10-3 The number of theoretical plates for the column is calculated as N = N. X NB A Using NĄ and NB, calculate the expected resolution for this separation. resolution: mm mm Consider a separation performed on a 30.0 mm long open tubular column with a 0.50 mm diameter and a 2.0 µm thick stationary phase. Compound A eluted at 12.63 min, compound B eluted at 13.24 min, and the unretained solvent eluted at 1.205 min. What are the adjusted retention times, t, and retention factors, k, for compounds A and B? TRA tR.B KA KB = = α = 11.425 12.035 NA = 9.481 What is the separation factor (relative retention), a, for this separation? 9.987 1.053 The widths at half-height, w₁/2, of the peaks for compounds A and B are 0.120 min and 0.253 min, respectively. Find the number of theoretical plates, N, and plate height, H, for each compound. 6.1480 x104 min min

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter15: Electrophoresis And Other Separation Methods

Section: Chapter Questions

Problem 5P

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Consider a separation performed on a 30.0 mm long open tubular column with a 0.50 mm diameter and a 2.0 µm thick stationary phase. Compound A eluted at 12.63 min, compound B eluted at 13.24 min, and the unretained solvent eluted at 1.205 min. What are the adjusted retention times, t, and retention factors, k, for compounds A and B? TRA KA = || TRB = KB = = min min
Consider a separation performed on a 50.0 mm long open tubular column with a 0.50 mm diameter and a 2.0 μm thick stationary phase. Compound A eluted at 12.44 min, compound B eluted at 13.43 min, and the unretained solvent eluted at 1.205 min. What are the adjusted retention times, t, and retention factors, k, for compounds A and B? TRA t'R,B KA = = = min min
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Methanol and Ethanol are separated in a capillary gas chromatography column with retention times of 370s and 385s, respectively and base width of 16.0s and 17.0s on a column 12.0 m long. An unretained air peak occurs at 10.0 s. (a) Calculate number of theoretical plate and plate height of the column using ethanol peak. Calculate the relative retention. Calculate retention factor for each analyte. (b) (c) (Show your Calculation)
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Substances A, B, C and D were found to have retention times of 8.3 min (A), 10.6 min (B), 12.4 min (C) and 13.5 min (D), respectively on an 15.0 cm long column. There was also an unretained species which appeared at 1.5 min. The widths of the peak bases were 0.90 min (A), 1.1 min (B), 1.3 min (C) and 0.80 min (D). Given this information listed above, please choose the most appropriate answer for the six questions listed below for the list of possible answers. Part A Calculate the capacity factor (k') for peak B and peak D. Part B. Calculate the resolution (R) between peaks B and D. Part C. What do the capacity factor and resolution tell you about the separation of peaks B and D on this column? Part D What are the theoretical plate number (N) for peaks Band D? Part E. What is the average plate height (H), based on the information in Part D and the column length listed above? Part F What would be the required length of a column to achieve a Rs of 2.07
A student researcher performed a chromatographic separation of caffeine and aspartame. The retention time for caffeine, tc, was found to be 209.6 s with a baseline peak width, w., of 14.4 s. The retention time for aspartame, ta, was 260.0 s with a baseline peak width, wa, of 21.2 s. The retention time for the unretained solvent methanol was 49.2 s. Calculate the average plate height, H, in micrometers for this separation, given that it was performed on a 22.1 cm long column. H = um %3D Calculate the resolution, R, for this separation using the widths of the peaks. R = Calculate the resolution if the number of theoretical plates were to increase by a factor of 2. R2N =
1. Methanol and ethanol are separated in a capillary GC column with retention times of 370 and 385 s, respectively, and half widths (W₁/2) of 9.42 and 10.0 s. An unretained butane peak occurs at 10.0 s. Calculate the separation factor and the resolution.
A solution of volume 1 mL, containing an equal parts mixture (by weight) of aspirin and paracetamol (acetaminophen), was analysed by HPLC, displaying peaks at retention times 1.5 mins (area integration 1500) and 2.0 mins (area integration 2500). An unknown solution, also volume 1 mL, was analysed under the same conditions and, among a number of other peaks, there was one at 2.0 mins (area integration 4000). (i) How can the 2.0 min peak in the unknown sample be confirmed as paracetamol? (ii) In a subsequent analysis, 5.0 mg of aspirin was dissolved in the unknown solution and an extra peak appeared in the HPLC at 1.5 mins (area integration 2000). Assuming the 2.0 min peak confirmed as paracetamol, determine its concentration (g L-¹) in the unknown sample and estimate the error in the determination.
4.Consider the peaks for pentafluorobenzene and benzene in the gas chromatogram shown here. The elution time for unretained solute is 1.06 min. The open tubular column is 30.0 m in length and 0.530 mm in diameter, with a layer of stationary phase 3.0 μm thick on the inner wall. a) Measruing the width, w, at the baseline on the chromatogram, find the number of plates for these two compounds b) Use your answer to (a) to find the resolution between the two peaks c) Using the number of plates N=sqrtN1*N2 with the values from (a) calcuate what the resolution should be and compare your answer with the measured resolution in b
9. Consider the chromatogram shown below (used with permission from the Honors Thesis of Mark Bickley, TU Chemistry alumnus). The chromatography column used to separate the three analytes (A, B, and C) is 17.0 cm in length. The elution time for an unretained solute is 2.05 min. 25 T0 7.5 100 Time (min) a) Calculate the adjusted retention time for compound B. b) Calculate the retention factor for compound B. c) What is the width (in minutes) at half-height of the peak associated with compound B? d) Based on your results from part c, how many plates are experienced by compound B? e) Based on your results from part d, what is the plate height (in um)? f) Calculate the unadjusted relative retention associated with compounds B and C. g) Calculate the relative retention associated with compounds B and C. h) Calculate the resolution associated with compounds B and C.