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Questions and Answers
What is the primary purpose of radio-frequency spectroscopy of nuclei in a magnetic field?
What is the primary purpose of radio-frequency spectroscopy of nuclei in a magnetic field?
What type of spectroscopy was used to discover the three-degree blackbody radiation?
What type of spectroscopy was used to discover the three-degree blackbody radiation?
Which of the following is a characteristic of potentiometry?
Which of the following is a characteristic of potentiometry?
Which of the following is a characteristic of amperometry?
Which of the following is a characteristic of amperometry?
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What is the primary purpose of electroanalytical methods?
What is the primary purpose of electroanalytical methods?
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What is the primary purpose of conductometry?
What is the primary purpose of conductometry?
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What is the first step in the process of chemical analysis?
What is the first step in the process of chemical analysis?
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What is the purpose of method modeling and plan in chemical analysis?
What is the purpose of method modeling and plan in chemical analysis?
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What step is typically the most time-consuming in the implementation of an analytical method?
What step is typically the most time-consuming in the implementation of an analytical method?
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What is the purpose of performing replicate measurements in chemical analysis?
What is the purpose of performing replicate measurements in chemical analysis?
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What step involves comparing the analyte's signal to standards of known concentration and a calibration blank solution?
What step involves comparing the analyte's signal to standards of known concentration and a calibration blank solution?
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What information must be presented in every analytical result?
What information must be presented in every analytical result?
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What is the purpose of an atomizer in atomic absorption spectroscopy?
What is the purpose of an atomizer in atomic absorption spectroscopy?
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Which type of lamp emits many narrow emission lines in atomic absorption spectroscopy?
Which type of lamp emits many narrow emission lines in atomic absorption spectroscopy?
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What is the purpose of a monochromator in atomic absorption spectroscopy?
What is the purpose of a monochromator in atomic absorption spectroscopy?
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In Flame Atomic Absorption Spectroscopy (FAAS), where does atomization of the sample occur?
In Flame Atomic Absorption Spectroscopy (FAAS), where does atomization of the sample occur?
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What is the function of the graphite tube in Graphite Furnace Atomic Absorption Spectroscopy (GFAAS)?
What is the function of the graphite tube in Graphite Furnace Atomic Absorption Spectroscopy (GFAAS)?
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What does the detector do in Graphite Furnace Atomic Absorption Spectroscopy?
What does the detector do in Graphite Furnace Atomic Absorption Spectroscopy?
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What is the main purpose of the quadrupole mass analyzer described in the text?
What is the main purpose of the quadrupole mass analyzer described in the text?
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What is the advantage of using a quadrupole as the first part of a tandem mass spectrometer?
What is the advantage of using a quadrupole as the first part of a tandem mass spectrometer?
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What is the purpose of using selected reaction monitoring (SRM) in a tandem mass spectrometer with a quadrupole?
What is the purpose of using selected reaction monitoring (SRM) in a tandem mass spectrometer with a quadrupole?
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How is an ion trap mass spectrometer different from a quadrupole mass spectrometer?
How is an ion trap mass spectrometer different from a quadrupole mass spectrometer?
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What is the advantage of an ion trap mass spectrometer over a quadrupole for full scan mode?
What is the advantage of an ion trap mass spectrometer over a quadrupole for full scan mode?
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What is the purpose of the second analyzer in a tandem mass spectrometer with a quadrupole?
What is the purpose of the second analyzer in a tandem mass spectrometer with a quadrupole?
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What technique was popular in the 80's to early 90's for ionizing non-volatile compounds?
What technique was popular in the 80's to early 90's for ionizing non-volatile compounds?
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What were the two most common matrices used in FAB?
What were the two most common matrices used in FAB?
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What types of adducts could form with the analyte ions in FAB?
What types of adducts could form with the analyte ions in FAB?
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What technique involved replacing the atom beam in FAB with a beam of ions, typically cesium ions?
What technique involved replacing the atom beam in FAB with a beam of ions, typically cesium ions?
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What is the principle behind Electrospray Ionization (ESI)?
What is the principle behind Electrospray Ionization (ESI)?
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What process occurs in ESI to eject the ions from the charged droplets?
What process occurs in ESI to eject the ions from the charged droplets?
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Study Notes
Methods of Chemical Analysis
- The objective of chemical analysis is to provide information to solve a problem or make a decision, whether using classical (wet chemical) or instrumental methods.
Steps of Chemical Analysis
- Define the problem, requiring understanding of analytical techniques, problem-solving skills, experience, and intuition.
- Model the method, including a specific statement of the problem, information about the sample and analyte.
- Obtain and store the sample.
- Prepare the sample, which usually requires the largest investment of time.
- Perform measurements, including replicates to establish precision.
- Compare results with standards, involving a proper comparison of the analyte's signal to that of appropriate standards.
- Refine data and perform statistical treatment, presenting the precision of the analytical method.
Radiation Sources
- Deuterium lamps (DL) and electrodeless discharge lamps (EDL) are popular radiation sources.
Atomizers
- Atomizers break analytes into free atoms to analyze elements for their atomic constituents.
- Flame atomizers and graphite tube atomizers are commonly used in atomic absorption spectroscopy.
- Flame Atomic Absorption Spectroscopy (FAAS) involves nebulizing a solution of the sample into a flame.
- Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) involves atomization in an open-ended graphite tube.
Monochromators
- A monochromator isolates a single resonance emission line from the hollow cathode lamp's many narrow emission lines.
- It collects light with many wavelengths and selects a narrow wavelength band.
Quadrupole Mass Analyzer
- A quadrupole mass analyzer uses a combination of radio-frequency (RF) and direct current (DC) voltages to select ions with a specific m/z or range of m/z.
- It is a low-resolution analyzer, often used in GC-MS and LC-MS applications.
- Quadrupole mass analyzers can be used in tandem mass spectrometry with selected reaction monitoring (SRM).
Ion Trap Mass Spectrometer
- Ion trap mass spectrometers are a type of three-dimensional quadrupole that can store and manipulate ions.
- They are more sensitive than simple quadrupole mass analyzers and can acquire tandem mass spectra.
Electroanalytical Methods
- Electroanalytical methods measure electrical signals or properties of a solution.
- Techniques include potentiometry (measuring electric potential), amperometry (measuring electric current), and conductometry (measuring conductance).
Fast Atom Bombardment (FAB) and Secondary Ion Mass Spectrometry (SIMS)
- FAB involves bombarding a sample with a beam of atoms, typically Ar or Xe, to ionize non-volatile compounds.
- The sample is mixed with a matrix, such as glycerol or 3-Nitrobenzoic acid, which allows the sample to refresh itself.
- SIMS replaces the atom beam with a beam of ions, typically cesium ions.
Electrospray Ionization (ESI)
- ESI creates an electrospray by applying a high voltage to a flow of liquid at atmospheric pressure, sometimes assisted by a concurrent flow of gas.
- The created spray is directed into the vacuum system of the mass spectrometer, where the droplets are de-solvated and ions are ejected and accelerated into the mass analyzer.
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Description
Learn about the steps involved in chemical analysis, from defining the problem to method modeling and planning. Understand the objectives behind performing chemical analysis using classical or instrumental methods.
