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Methods for Detecting and Measuring Toxic Chemicals

Description: This quiz evaluates your knowledge of various methods used to detect and measure toxic chemicals in the environment.
Number of Questions: 15
Created by:
Tags: toxicology environmental chemistry analytical chemistry
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Which of the following is a widely used method for detecting and measuring organic pollutants in environmental samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is a powerful analytical technique that combines the separation capabilities of gas chromatography with the identification capabilities of mass spectrometry. It is commonly used to analyze complex mixtures of organic compounds, including pesticides, dioxins, and polycyclic aromatic hydrocarbons (PAHs).

What is the principle behind the operation of an atomic absorption spectrometer?

  1. Absorption of light by atoms in a flame

  2. Emission of light by atoms in a flame

  3. Fluorescence of atoms in a flame

  4. Phosphorescence of atoms in a flame


Correct Option: A
Explanation:

Atomic absorption spectroscopy (AAS) is based on the principle that atoms in a flame absorb light at specific wavelengths corresponding to their electronic transitions. The amount of light absorbed is proportional to the concentration of the atoms in the sample.

Which of the following is a commonly used method for detecting and measuring heavy metals in environmental samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: D
Explanation:

ICP-MS is a highly sensitive analytical technique used to measure the elemental composition of a sample. It is commonly employed to determine the concentrations of heavy metals, such as lead, mercury, and cadmium, in environmental samples.

What is the purpose of a derivatization step in the analysis of certain organic compounds by gas chromatography?

  1. To increase the volatility of the compounds

  2. To decrease the volatility of the compounds

  3. To improve the separation of the compounds

  4. To enhance the sensitivity of the detector


Correct Option: A
Explanation:

Derivatization is often performed to increase the volatility of organic compounds that are not sufficiently volatile for analysis by gas chromatography. This is achieved by chemically modifying the compounds to make them more volatile, thus enabling their separation and detection.

Which of the following is a common method for detecting and measuring volatile organic compounds (VOCs) in air samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is widely used for the analysis of VOCs in air samples due to its high sensitivity and ability to separate and identify a wide range of compounds. VOCs are typically collected on sorbent tubes or canisters and then analyzed by GC-MS.

What is the role of a mobile phase in high-performance liquid chromatography (HPLC)?

  1. To dissolve the sample

  2. To carry the sample through the column

  3. To react with the sample

  4. To detect the sample


Correct Option: B
Explanation:

In HPLC, the mobile phase is a liquid that carries the sample through the chromatographic column. The mobile phase is chosen based on its ability to dissolve the sample and to promote the separation of the analytes.

Which of the following is a common method for detecting and measuring pesticides in food samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is commonly used for the analysis of pesticides in food samples due to its high sensitivity and ability to separate and identify a wide range of compounds. Pesticides are typically extracted from the food matrix and then analyzed by GC-MS.

What is the principle behind the operation of an ion chromatograph?

  1. Separation of ions based on their size

  2. Separation of ions based on their charge

  3. Separation of ions based on their mass

  4. Separation of ions based on their volatility


Correct Option: B
Explanation:

Ion chromatography is a technique used to separate and measure ions in a sample. It works by passing the sample through a column packed with a stationary phase that has a specific affinity for certain ions. The ions are separated based on their charge and elute from the column at different times.

Which of the following is a common method for detecting and measuring dioxins and furans in environmental samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is commonly used for the analysis of dioxins and furans in environmental samples due to its high sensitivity and ability to separate and identify these compounds. Dioxins and furans are typically extracted from the sample matrix and then analyzed by GC-MS.

What is the purpose of a sample preparation step in the analysis of environmental samples?

  1. To remove interferences

  2. To concentrate the analytes

  3. To derivatize the analytes

  4. All of the above


Correct Option: D
Explanation:

Sample preparation is an important step in the analysis of environmental samples. It involves a series of procedures aimed at removing interferences, concentrating the analytes, and derivatizing the analytes (if necessary) to improve their detectability and chromatographic behavior.

Which of the following is a common method for detecting and measuring polycyclic aromatic hydrocarbons (PAHs) in environmental samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is commonly used for the analysis of PAHs in environmental samples due to its high sensitivity and ability to separate and identify these compounds. PAHs are typically extracted from the sample matrix and then analyzed by GC-MS.

What is the role of a stationary phase in gas chromatography?

  1. To dissolve the sample

  2. To carry the sample through the column

  3. To separate the analytes

  4. To detect the analytes


Correct Option: C
Explanation:

In gas chromatography, the stationary phase is a solid or liquid coating on the inside of the chromatographic column. The stationary phase interacts with the analytes in the sample, causing them to separate and elute from the column at different times.

Which of the following is a common method for detecting and measuring polychlorinated biphenyls (PCBs) in environmental samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is commonly used for the analysis of PCBs in environmental samples due to its high sensitivity and ability to separate and identify these compounds. PCBs are typically extracted from the sample matrix and then analyzed by GC-MS.

What is the purpose of a calibration curve in quantitative analysis?

  1. To determine the concentration of an analyte in a sample

  2. To identify the analytes in a sample

  3. To separate the analytes in a sample

  4. To detect the analytes in a sample


Correct Option: A
Explanation:

A calibration curve is a graphical representation of the relationship between the concentration of an analyte in a sample and the corresponding instrument response. It is used to determine the concentration of an analyte in an unknown sample by comparing its instrument response to the calibration curve.

Which of the following is a common method for detecting and measuring volatile organic compounds (VOCs) in water samples?

  1. Gas chromatography-mass spectrometry (GC-MS)

  2. High-performance liquid chromatography (HPLC)

  3. Atomic absorption spectroscopy (AAS)

  4. Inductively coupled plasma mass spectrometry (ICP-MS)


Correct Option: A
Explanation:

GC-MS is commonly used for the analysis of VOCs in water samples due to its high sensitivity and ability to separate and identify a wide range of compounds. VOCs are typically purged from the water sample and then analyzed by GC-MS.

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