Principles of Instrumental Analysis
7th Edition
ISBN: 9781305577213
Author: Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher: Cengage Learning
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Chapter 27, Problem 27.20QAP
The same polar compound is gas chromatographed on an SE-30 (very nonpolar) column and then on a Carbowax 20M (very polar column). I low will K=cS/cM vary between the two columns?
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A gas chromatogram of a mixture of toluene and ethyl
(a) Measure w1/2 for each peak to the nearest 0.1 mm. When the thickness of the pen trace is significant relative to the length being measured, it is important to take the pen width into account. It is best to measure from the edge of one trace to the corresponding edge of the other trace, as shown at the bottom of the left column.
(b) Find the number of theoretical plates and the plate height for each peak.
Internal standard. A mixture containing 12.8 mM analyte (X) and 44.4 mM standard (S) gave chromatographic peak areas of 306 for X and 511 for S. A second solution containing an unknown quantity of X plus 55.5 mM S had peak areas of 251 for X and 563 for S. Find [X] in the second solution.
Chapter 27 Solutions
Principles of Instrumental Analysis
Ch. 27 - Prob. 27.1QAPCh. 27 - Prob. 27.2QAPCh. 27 - Prob. 27.3QAPCh. 27 - Prob. 27.4QAPCh. 27 - Prob. 27.5QAPCh. 27 - Prob. 27.6QAPCh. 27 - Prob. 27.7QAPCh. 27 - Prob. 27.8QAPCh. 27 - Prob. 27.9QAPCh. 27 - What are hyphenated GC methods? Briefly describe...
Ch. 27 - Prob. 27.11QAPCh. 27 - Prob. 27.12QAPCh. 27 - Prob. 27.13QAPCh. 27 - Prob. 27.14QAPCh. 27 - Prob. 27.15QAPCh. 27 - Prob. 27.16QAPCh. 27 - Prob. 27.17QAPCh. 27 - Prob. 27.18QAPCh. 27 - Prob. 27.19QAPCh. 27 - The same polar compound is gas chromatographed on...Ch. 27 - Prob. 27.21QAPCh. 27 - Prob. 27.22QAPCh. 27 - Prob. 27.23QAPCh. 27 - Prob. 27.24QAPCh. 27 - Prob. 27.25QAPCh. 27 - Prob. 27.26QAPCh. 27 - Prob. 27.27QAPCh. 27 - Prob. 27.28QAPCh. 27 - Why is GSC not used nearly as extensively as GLC?Ch. 27 - Prob. 27.30QAP
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- C23-7arrow_forwardThe options are larger or smaller.arrow_forwardConsider the peaks for heptane (14.56 min) and p-difluorobenzene (14.77 min) in the chromatogram. The column is 30.0 m long. (a) Measure w1/2 for each peak and calculate the number of plates and the plate height for each. (b) From w1/2, compute w for each peak and find the resolution between the two peaks.arrow_forward
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- two chromatograms after LC separation. Which chromatogram is better to proceed for MS analysis? What mobile phase condition/composition (LC separation) was used?arrow_forwardA student analyzes sample 1, and sample 2 chromatograms of a mixture containing two compounds (A + B). The following data is obtained: Sample 1: Retention time Area Height % Area 0.210 19.20 15.68 5.57 0.650 243.62 89.37 70.74 1.74 81.57 13.42 23.68 Sample 2: 0.290 64.81 49.90 12.17 0.69 11.61 4.19 2.18 1.95 456.31 43.46 85.66 Using the data from the four compounds below, answer the following questions: Compound (b.p. °C) Retention time Area Height % Area Air 0.280 14.29 8.85 2.81 Hexane (69) 0.666 93.40 33.76 18.34 Cyclohexane (80.7) 0.980 124.66 30.48 24.48 Pentane (98.4) 1.216 112.27 24.18 22.05 Toluene (110.6) 1.830 164.59 21.64 32.32arrow_forwardInternal standard (As , Cs ), analyte with known concentration (Ax , Cx ) In a chromatographic equipment, a solution containing 0.006727 X and 0.008331 M S give peak area of Ax= 2316 and As= 207. To analyze an unknown sample, 5.0mL of 0.008331M S was added to 5.0mL of X, and the mixture was diluted to 50.0mL. This mixture gave a chromatography spectrum with area Ax= 3206 and As= 200. Find Cx.arrow_forward
- A young researcher set out to develop a method for quantifying the polycyclic aromatic hydrocarbon (PAH) content in a contaminated soil sample using open tubular gas chromatography. During the initial stages of method development, the researcher was unable to separate the early eluting compounds, anthracene and naphthalene, with baseline resolution. Select the possible modifications the researcher could make to improve the resolution. use a column with a smaller inner diameter decrease the column length increase the stationary phase thickness increase the temperature choose a different stationary phasearrow_forwardWhich of the following are characteristics of normal-phase chromatography? I - The stationary phase is polar. II - The mobile phase is more polar than the stationary phase. III - The eluent strength increases as the mobile phase becomes less polar. IV - The eluent strength increases as the mobile phase becomes more polar. V - the stationary phase is nonpolar. Answers to choose from: I and IV I, IV and V I and III II and IV II and V ...and why?arrow_forwardInternal standard. A solution containing 3.47 mM X (analyte) and 1.72 mM S (standard) gave peak areas of 3 473 and 10 222, respectively, in a chromatographic analysis. Then 1.00 mL of 8.47 mM S was added to 5.00 mL of unknown X, and the mixed solution was diluted to 10.0 mL. This solution gave peak areas of 5 428 and 4 431 for X and S, respectively. (a) Find the response factor for X relative to S in Equation 5-9. (b) Find [S] (mM) in the 10.0 mL of mixed solution. (c) Find [X] (mM) in the 10.0 mL of mixed solution.(d) Find [X] in the original unknown.arrow_forward
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