Interpretation:
An internal standard and its uses needs to be explained.
Concept introduction:
Use of an internal standard before actual sample analysis is an established method in analytical tests and is one important step towards eliminating/reducing the sources of errors and ensuring the accuracy and precision of the results.
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Answer to Problem 10.1QAP
An internal standard is a chemical substance, added to the sample, blank or calibration standards to identify and account for uncontrollable variables. The uncontrollable variables are expected to affect the internal standard and the analyte to a similar extent.
Explanation of Solution
Before actual analytical analysis of a substance, a blank and/or a calibration standard is run. This consists of a chemical substance of known composition and purity. It is added in a known quantity. This responds to the analytical and measurement processes as will the actual substance sample.
This is used to draw a calibration curve with the signals of internal standard on Y axis.
The accuracy of the results is increased as the instrument noise gets eliminated. This is because the signal to noise ratio is the same for the internal standard as for the substance under analysis.
Running the internal standards prior to running the analyte, improves the accuracy of the results. The internal standard, however, is to be properly selected.
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Chapter 10 Solutions
INSTRUMENTAL ANALYSIS-ACCESS >CUSTOM<
- Problem 5-48 Assign R or S configurations to the chirality centers in ascorbic acid (vitamin C). OH H OH HO CH2OH Ascorbic acid O H Problem 5-49 Assign R or S stereochemistry to the chirality centers in the following Newman projections: H Cl H CH3 H3C. OH H3C (a) H H H3C (b) CH3 H Problem 5-52 Draw the meso form of each of the following molecules, and indicate the plane of symmetry in each: OH OH (a) CH3CHCH2CH2CHCH3 CH3 H3C. -OH (c) H3C CH3 (b) Problem 5-66 Assign R or S configurations to the chiral centers in cephalexin, trade-named Keflex, the most widely prescribed antibiotic in the United States. H2N H IHH S Cephalexin N. CH3 CO₂Harrow_forwardSteps and explanationn please.arrow_forwardSteps and explanationn please.arrow_forward
- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage LearningChemistry for Engineering StudentsChemistryISBN:9781285199023Author:Lawrence S. Brown, Tom HolmePublisher:Cengage Learning
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