None Which of the following statement about chromatography is CORRECT?In ion-exchange chromatography, charged substances are separated via column materials thatcarry a same charge.Using gradient elution in LC can shorten the separation time without sacrificing the resolution ofearly peaks.In normal-phase chromatography, if the order of solute polarities is A>B>C, then the order ofretention time will be C>B>A (i.e. A will be eluted out first).In size-exclusion HPLC, larger molecules will be eluted out slower than smaller molecules.

Explanation:Correct Statement:B) In gradient elution, the composition of the mobile phase is…

Answered: Which of the following statement about…

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter26: An Introduction To Chromatographic Separations

Section: Chapter Questions

Problem 26.14QAP

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A method of quantitative determination of the concentration of constituentsof a sample analyzed by gas chromatography is area normalization. Thiscomplete elution of all sample constituents is required. Thearea of each peak is measured and corrected for the detector response to the diffe- renteseluatos. This correction involves dividing the area by an empiricalcorrection factorDetermined. The concen ration of the analyte is found from the ratio between itscorrected and the total corrected area of all peaks. For a chromatogram containing threerelative areas were determined as 16.4; 45,2; and 30.2, in the order ofincreased retention time. Calculate the percentage of each compound if therelative responses from the detector are 0.65, 0.73 and 0.85, respectively.
A solvent passes through a chromatography column in 3.87 min, but the solute requires 7.60 min. What is the retention factor, k? k = What fraction of the time does the solute spend in the mobile phase in the column? t fraction in mobile phase = The volume of the stationary phase is 0.133 times the volume of the mobile phase in the column (Vs = 0.133VM). What is the distribution constant, Kp, for this system? KD = %3D
Q4 (a) Analyze the importance of dropping mercury electrode on polarography. (b) (i) Calculate the molarity of MgSO4 in a solution containing 1.5 g ofMgSO4 in a volume of 250 mL?(ii) Calculate the weight of MgSO4 in grams which is present in 100mL of 0.076 M MgSO4?(c) Evaluate the key differences between paper chromatography and gaschromatography
In a reverse-phase separation, a solute was found to have a retention time of 19.6 min, while an unretained peak had a retention time of 1.45 min when the mobile phase was 20/80 v/v% methanol/water. (b) Calculate the k’ for the solute. (c) Calculate the new k’ if the mobile phase is changed to 60/40 methanol/water assuming identical void volume. (d) Calculate a solvent composition that would bring k’ from initial value to a value of 1.20 using tetrahydrofuran/water mobile phase rather than 20/80 v/v % methanol/water.
Explain the following terms used in chromatography i) Dead time ii) Number of theoretical plates Describe the sample properties that would be suitable for; i) Gas chromatography (GC) analysis ii) High-performance liquid chromatography (HPLC) analysis
In stationary chromatography, the distribution (K) is the main criterion for the division of species in the sample between the two functions of the system, which factors depend on
4.columns with one million theoretical plates operating by slip flow. The figure shows the gradient separation of two forms of fluorescently labeled bovine serum albumin separated on a)50 x 2.1 mm UHPLC column of 1.7 µm C4 silica particles and b)10 mm x 75µm colloidal crystal column of 470 nm C4 silica nanoparticles. What are the main differences in the chromatogram? What is the reason for the difference? Why does the colloidal crystal column have such a high number of theoretical plates (N)? How is the problem of high pressures with very small particles overcome?
Researchers used gas chromatography to determine the % v/v methyl salicylate in rubbing alcohol [Van Atta, R. E.; Van Atta, R. L. J. Chem. Educ. 1980, 57, 230-231]. A set of standard additions was prepared by transferring 20.00 mL of rubbing alcohol to separate 25 - mL volumetric flasks and pipeting 0.00 mL, 0.20 mL, and 0.50 mL of methyl salicylate to the flasks. All three flasks were diluted to volume using isopropanol. Analysis of the three samples gave peak heights for methyl salicylate of 57.00 mm, 88.5 mm, and 132.5 mm, respectively. Determine the % v/v methyl salicylate in the rubbing alcohol.
Which statements are true for molecular exclusion chromatography?I Molecular exclusion chromatography separates on the basis of size.II Small molecules that freely pass through the stationary phase, Kav = 0.III Small molecules can fit in the pores of the stationary phase and effectively pass through a larger volume, and elute last.IV The pores in the stationary phase are too small for large molecules to pass through, so large molecules elute last.V Molecular exclusion chromatography with a hydrophilic stationary phase and an aqueous solvent is called gel permeation chromatography. A. II and V B. I, II, and IV C. III, IV, and V D. No correct combinations given above E. I, III, and IV F. I, II, III, and V
In chromatography, the compound that is least soluble in the mobile phase a) Travels the furthest away from the line of origin b) Stays closest to the line of origin
A chromatography column has a stationary phase volume that is 0.130 times the volume of the mobile phase. Find the retention factor, k, for a solute with each of the given distribution constants, Kp. Кр 3D 2.68 k = Kp = 19.1 k =
In molecular exclusion (size exclusion) chromatography, the molecules have the longest retention times. a) the larger molecules b) the smaller molecules

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