The table contains data for a liquid chromatography separation of four compounds, A, B, C, and D, on a 25.0 cm column. Retention Width at the Compound time (min) base (min) A 5.14 0.448 13.0 1.08 C 14.0 1.15 D 23.6 1.89 Calculate the number of theoretical plates, N, for each peak. NA = NB = Nc = Np = What is the average number of theoretical plates, Nave , for the column? Navg

The table contains data for a liquid chromatography separation of four compounds, A, B, C, and D, on a 25.0 cm column. Retention Width at the Compound time (min) base (min) A 5.14 0.448 13.0 1.08 C 14.0 1.15 D 23.6 1.89 Calculate the number of theoretical plates, N, for each peak. NA = NB = Nc = Np = What is the average number of theoretical plates, Nave , for the column? Navg

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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An analyst was measuring the performance of a HPLC column. The test solute was Toluene (5 µL). The column was a 4.6 mm i.d. column, 150 mm in length and packed with 5 µm C18 particles. The mobile phase was 40/60 water/methanol and the flow rate was 0.80 mL/min. The void time (to) was 1.86 minutes The retention time of the toluene sample was 14.50 min. The standard deviation of the peak was 7.0542 (s). 2a. The mobile phase velocity was? 0.0806 mm/s 0.1344 mm/s 1.344 mm/s 1.344 x 10³ mm/s (i) (ii) (iv) 2b. The number of theoretical plates was? (i) (ii) (iii) (iv) 2c. The height equivalent to a theoretical plate was? 1.041x10³ m 1.015x105 m 9.862x10-6 m 1.186x10¹² m (i) (ii) (iii) (iv) 4802 15210 24705 9848 2d. The reduced plate height was? (i) 2.03 (ii) 1.97 (iii) 7.55 (iv) 2.08 2e. The column was? (i) (ii) Extremely well packed Well packed Poorly packed (iii) (iv) Insufficient information to decide about the quality of the column
An unknown compound was analyzed by GC with octane (C3H18) and decane (C10H22). The adjusted retention times were 14.6 min for octane, and 31.6 min for decane. Calculate the retention index for the unknown if its adjusted retention time was 21.2 min.
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A new method is proposed to simultaneously detectand separatefour foodadditives by reversed-phase liquid chromatography. The data were obtained using theliquid chromatographic column with a flow rate of 0.5 mL per min and with the followingparameters: Pore size 100 A Particle Size 3.5 Internal diameter 4.6 mm Length 150 mm The food additives found in the sample resulted in the following data: ( see image for table) a.Calculate the number of plates from each peak. b.Calculate the plate height for the column. c.Retention factor for each peak.
Chromatographic analysis using gas-liquid chromatography with a 40-cm packed column gave the following data: retention time, Compound width, min min Air 1.9 C7H14 (a 10.0 0.76 cycloalkane) C7H12 (a 10.9 0.82 cycloalkene) Toluene 13.4 1.00 Determine the average number of plates. 2014.678 2718.045 3098.354 None of the above
A chromatographic column was found to have the following constants: A= 0.01 cm, B= 0.30 cmis and C=0.015s. What are the optimum flow rate? A none of the choices Bp-15 cmis p-45 cm/s D u-3.6 cmis E-26 cm/s
The write-up says “A C18-silica column is used in this experiment, a 0.46 x 15 cm column with 5-µm particles. Equilibrate the column with 20 empty column volumes of 0.010 M phosphate buffer (pH 7.2) at a flow rate of 1.2 mL/min before beginning chromatography.” Show the calculation for how much mobile phase you would use (volume) and how long it will take to equilibrate the column.
A mixture of three components is separated using paper chromatography, and each component is analyzed using absorption. With standards containing 100 ppm of each component run simultaneously, the following data were obtained: cmpd A, 0.72 absorbance; B, 0.55; C, 0.80. For the unknown mixture, the data obtined when run under identical conditions were as follows: cmpd A, .0.15 absorbance, B, 0.84; C, 0.75. a) Calculate the relative percentage composition of the unknown mixture. b) The distances traveled by the three components were 8.5, 6.3, and 5.5 cm, respectively. Sketch the appearance of the paper chromatogram. Label each spot. c) Calculate the Rf values if the solvent front is 18 cm.
A 20-cm long packed column was used to perform the separation of A and B by LC. TRA=16.28 min, TR,B=17.50 min, WA=1.11 min, WB=1.19 min, tм=1.30 min. (a) Calculate the retention factor (k') for A and B. (b) Calculate the average number of theoretical plates and plate height.
Consider the following chromatographic data for the separation of methylparaben from ethylparaben in a sunscreen sample. Compound Methylparaben Retention time, tr (min). Width at base of peak, Wb (min) 3.2 4.2 0.55 0.60 Ethylparaben A compound not retained by the column in this analysis had a tm of 0.75 minutes. The column used was a C18 column with a mobile phase mixture of 75% methanol and 25% water. Calculate the number of theoretical plates for ethylparaben.
The figure below shows a portion of a GC chromatogram for a mixture of two aromatic compounds labeled A and B. The separation employed a 2.50 meter packed column under isothermal conditions (90 °C) and a flow rate of 10 mL/min. in (c) Detector Signal 300.0 250.0 200.0 150.0 100.0 50.0 0.0 1.0 Unretained 1.2 1.3 1.4 1.5 time (min) Calculate the retention factors for each peak. 1.5
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