Researchers used gas chromatography to determine the % v/v methyl salicylate in rubbingalcohol [Van Atta, R. E.; Van Atta, R. L. J. Chem. Educ. 1980, 57, 230-231]. A set ofstandard 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 theflasks. All three flasks were diluted to volume using isopropanol. Analysis of the three samplesgave 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.

### Step 1: Understand the Principle of Standard AdditionsThe standard additions method involves…

Answered: Researchers used gas chromatography to…

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

Chapter33: Automated Methods Of Analysis

Section: Chapter Questions

Problem 33.8QAP

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in HPLC, what does it mean to equilibrate the system. Let us assume that the system is currently running 100%B. You have told them to run the first standard of caffeine using Reverse Phase chromatography with a C18 column, 30% A (Water/0.1%TFA) and 70% B (MeOH/0.1%TFA).What should I equilibrate the system to and for how long?
A scientist wishes to measure the concentration of methyl benzoate in a plant stream by gas chromatography. He prepares a sample of butyl benzoate to use as an internal standard. The results of a preliminary run, which used a solution known to contain 1.37 mg/mL of methyl benzoate (peak A) and 1.51 mg/mL of butyl benzoate (peak B), are shown. The area of peak A is determined to be 3.40×102 and the area of peak B is determined to be 398 measured in arbitrary units by the computer. To measure the sample, 1.00 mL of a standard sample of butyl benzoate containing 2.49 mg/mL is mixed with 1.00 mL of the plant stream material. Analysis of the mixture gave a peak area of 437 for peak A and 415 for peak B. What is the concentration of methyl benzoate in the plant stream?
hree components in a mixture have varying distribution constants between the mobile phase and the stationary phass One of the components has a very low distribution constant, Would this component likely elute first or last and how would you design an experiment or modify the components of the separation to make it perform in the opposite manner?
Describe briefly how liquid-liquid extraction can be used to separate (not necessarily 100% separation) an analyte, A, from a potential inference, B in a liquid sample. What must be the most important difference between A and B for the separation to succeed?
In ion-exclusion chromatography, ions are separated from nonelectrolytes (uncharged molecules) by an ion-exchange column. Nonelectrolytes penetrate the stationary phase, whereas ions with charge of the same sign as that of the stationary phase are repelled by the stationary phase. Because electrolytes have access to less of the column volume, they are eluted before nonelectrolytes. A mixture of trichloroacetic acid (TCA, pKa 5 20.5), dichloroacetic acid (DCA, pKa 5 1.1), and monochloroacetic acid (MCA, pKa 5 2.86) was separated by passage through a cation-exchange resin eluted with 0.01 M HCl. The order of elution was TCA , DCA , MCA. Explain why the three acids are separated and the order of elution.
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Does KMNO4 oxidize or reduce an analyte during permanganimetry?
5) Retention factors for three solutes separated on a C8 nonpolar stationary phase at pH = 3 are given. Eluant was a 70:30 vol/vol mixture of 50 mM citrate buffer and methanol. a)Draw the dominant chemical structure of each of the substances at pH = 3. b)The retention factor for acetophenone is 4.21, for salicylic acid is 2.97, and for nicotine is zero. Explain the different retention factors.
1. Calculate the capacity factor, k' for methyl paraben and propyl paraben. 2. Calculate the selectivity factor, a for the two-component mixture.
Arrange in INCREASING Rf if the mixture underwent paper chromatography with the same solvent system. Explain how you get the answer I. 2-chloropentaneII. pentanoic acidIII. cyclopentaneIV. pentanal a. II = IV < III < I b.II < IV < I < III c.I < II < III < IV d.III < I < IV < II

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