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Quantitative analysis by selected ion monitoring. Caffeine in beverages and urine can be

Quantitative Chemical Analysis | 8th Edition | ISBN: 9781429218153 | Authors: Daniel C. Harris ISBN: 9781429218153 475

Solution for problem 21-H Chapter 21

Quantitative Chemical Analysis | 8th Edition

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Quantitative Chemical Analysis | 8th Edition | ISBN: 9781429218153 | Authors: Daniel C. Harris

Quantitative Chemical Analysis | 8th Edition

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Problem 21-H

Quantitative analysis by selected ion monitoring. Caffeine in beverages and urine can be measured by adding caffeine-D3 as an internal standard and using selected ion monitoring to measure each compound by gas chromatography. The figure shows mass chromatograms of caffeine (m/z 194) and caffeine-D3 (m/z 197), which have nearly the same retention time. Selected ion monitoring mass chromatogram showing caffeine and caffeine-D3 eluted from a capillary gas chromatography column. [From D. W. Hill, B. T. McSharry, and L. S. Trzupek, Quantitative Analysis by Isotopic Dilution Using Mass Spectrometry, J. Chem. Ed. 1988, 65, 907.] Ion counts 2 106 1 106 7.0 7.5 8.0 Time (min) Caffeine (680 mg/L) m/z = 194 Caffeine-D3 (370 mg/L) m/z = 197 1 000 600 800 150 M MM M (a) (b) (c) (d) 533 Suppose that the following data were obtained for standard mixtures: Caffeine Caffeine-D3 Caffeine Caffeine-D3 (mg/L) (mg/L) peak area peak area 13.60 102 3.70 102 11 438 2 992 6.80 102 3.70 102 6 068 3 237 3.40 102 3.70 102 2 755 2 819 NOTE: Injected volume was different in all three runs. (a) Compute the mean response factor in the equation (b) For analysis of a cola beverage, 1.000 mL of beverage was treated with 50.0 L of standard solution containing 1.11 g/L caffeine-D3 in methanol. The combined solution was passed through a solid-phase extraction cartridge that retains caffeine. Polar solutes were washed off with water. Then the caffeine was washed off the cartridge with an organic solvent and the solvent was evaporated to dryness. The residue was dissolved in 50 L of methanol for gas chromatography. Peak areas were 1 144 for m/z 197 and 1 733 for m/z 194. Find the concentration of caffeine (mg/L) in the beverage. A

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1 Chapter 2 Elements, Compounds, and The Periodic Table Objectives: ­Periodic Table ­Chemical Equations ­Writing and naming chemical compounds Periodic Table: ­The rows in the table are called periods. ­The columns are called groups or families. ­The table is arranged in order of increasing atomic number (# e's, or # p's). ­The elements in a group have the same chemical properties. For example, Li, Na, and K react with water and release hydrogen gas. ­Ten elements in the center (Groups IIIB, IIB) are referred to as transition elements. ­Elements in Group IA are called alkali metals. ­Elements in Group IIA are called alkali earth metals. ­Elements in Group VIIA are called halogen

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Chapter 21, Problem 21-H is Solved
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Textbook: Quantitative Chemical Analysis
Edition: 8
Author: Daniel C. Harris
ISBN: 9781429218153

This textbook survival guide was created for the textbook: Quantitative Chemical Analysis, edition: 8. The answer to “Quantitative analysis by selected ion monitoring. Caffeine in beverages and urine can be measured by adding caffeine-D3 as an internal standard and using selected ion monitoring to measure each compound by gas chromatography. The figure shows mass chromatograms of caffeine (m/z 194) and caffeine-D3 (m/z 197), which have nearly the same retention time. Selected ion monitoring mass chromatogram showing caffeine and caffeine-D3 eluted from a capillary gas chromatography column. [From D. W. Hill, B. T. McSharry, and L. S. Trzupek, Quantitative Analysis by Isotopic Dilution Using Mass Spectrometry, J. Chem. Ed. 1988, 65, 907.] Ion counts 2 106 1 106 7.0 7.5 8.0 Time (min) Caffeine (680 mg/L) m/z = 194 Caffeine-D3 (370 mg/L) m/z = 197 1 000 600 800 150 M MM M (a) (b) (c) (d) 533 Suppose that the following data were obtained for standard mixtures: Caffeine Caffeine-D3 Caffeine Caffeine-D3 (mg/L) (mg/L) peak area peak area 13.60 102 3.70 102 11 438 2 992 6.80 102 3.70 102 6 068 3 237 3.40 102 3.70 102 2 755 2 819 NOTE: Injected volume was different in all three runs. (a) Compute the mean response factor in the equation (b) For analysis of a cola beverage, 1.000 mL of beverage was treated with 50.0 L of standard solution containing 1.11 g/L caffeine-D3 in methanol. The combined solution was passed through a solid-phase extraction cartridge that retains caffeine. Polar solutes were washed off with water. Then the caffeine was washed off the cartridge with an organic solvent and the solvent was evaporated to dryness. The residue was dissolved in 50 L of methanol for gas chromatography. Peak areas were 1 144 for m/z 197 and 1 733 for m/z 194. Find the concentration of caffeine (mg/L) in the beverage. A” is broken down into a number of easy to follow steps, and 292 words. Quantitative Chemical Analysis was written by and is associated to the ISBN: 9781429218153. This full solution covers the following key subjects: . This expansive textbook survival guide covers 55 chapters, and 1224 solutions. The full step-by-step solution to problem: 21-H from chapter: 21 was answered by , our top Chemistry solution expert on 03/16/18, 04:33PM. Since the solution to 21-H from 21 chapter was answered, more than 512 students have viewed the full step-by-step answer.

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