Chapter 9, Problem 9.1QAP

Interpretation Introduction

(a)

Interpretation:

The term releasing agent needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Cations which interact with the analyte and eliminate the chemical interferences are called releasing agents.

Explanation of Solution

There are chemical interferences caused by some compounds in the atomic absorption spectroscopy. Releasing agents are used to get rid of these interferences. These are cations which preferentially react with interferent and prevent the chemical interferences through their interactions with analyte.

An example of releasing agent is strontium which is used in calcium determination as it preferentially reacts with phosphate.

Interpretation Introduction

(b)

Interpretation:

The term protective agent needs to be explained.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Protective agents are substances forming stable volatile species and overcoming interference in Atomic absorption spectroscopy.

Explanation of Solution

Protective agents are those substances which when used in atomic absorption spectroscopy undergo reaction with the analytes to form stable volatile species and thereby eliminating other substances’ interference.

An example of protective agent is EDTA which in the calcium determination helps in eliminating aluminum, silicon, sulfate, phosphate interference.

Interpretation Introduction

(c)

Interpretation:

The term ionization suppressor needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Ionization suppressor provides more electron concentration to be added causing improvement in the sensitivity.

Explanation of Solution

During AAS or Atomic emission spectrometry, ionization of the metal ions tends to occur when the analyte samples come under high temperatures which affects the atomic emission or absorption lines intensity. The sensitivity of the instrument increases owing to the high concentration of electrons that get added by the ionization suppressor.

Interpretation Introduction

(d)

Interpretation:

The term atomization needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Process by which samples are converted to atoms is called atomization.

Explanation of Solution

The process by which samples are vaporized followed by mixing with fuel and then placed in flame where because of the heat, it gets vaporized and decomposed into atoms is called atomization. In other words, it could be said that atomization is a process by which samples are converted to atoms.

Interpretation Introduction

(e)

Interpretation:

The term pressure broadening needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

The process by which the collision of absorbing or emitting species with other ions causes broadening of spectral lines than normal ones is called pressure broadening.

Explanation of Solution

In Atomic absorption spectroscopy, AAS or AES, collision takes place between the absorbing or emitting species and other ions or atoms. This causes increase in the pressure broadening or collision broadening. The spectral lines so obtained are two to three times broader than the normal recorded ones. This whole process is referred to as pressure broadening.

Interpretation Introduction

(f)

Interpretation:

The term hollow cathode lamp needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Hollow cathode tube is a glass tube commonly used in atomic absorption measurements.

Explanation of Solution

Hollow cathode tube is a glass tube having a metal cathode and tungsten anode and contains inert gas. This is generally used in atomic absorption measurements as when large currents are passed some of the metal atoms get excited and radiate before they return to their ground state.

Interpretation Introduction

(g)

Interpretation:

The term sputtering needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Process of atomic cloud formation in the hollow cathode lamp is called sputtering.

Explanation of Solution

Atomic clouds are produced in hollow cathode lamp as metal atoms are dislodged from the cathode by gaseous cations. This process is referred to as sputtering.

Interpretation Introduction

(h)

Interpretation:

The term self-absorption needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Self-absorption refers to the absorbing back of the emitted radiation by non-excited atoms in the lamp.

Explanation of Solution

The non-excited atoms in the hollow cathode lamp absorb the radiation emitted by the excited atoms in the lamp. This phenomenon is referred to as self-absorption.

Interpretation Introduction

(i)

Interpretation:

The term spectral interference needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Spectral interference is phenomenon of overlapping of absorption line of analyte by another interfering species.

Explanation of Solution

The phenomenon wherein an analyte’s emission line or the absorption line is closer to another interfering species or is overlapping with another interfering species, then it is called spectral interference.

Interpretation Introduction

(j)

Interpretation:

The term chemical interference needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Chemical interference is the change in an analyte’s emission or absorption properties because of chemical processes that happen through atomization.

Explanation of Solution

The chemical process happening through atomization causes a lot of changes in analyte’s emission properties or in its absorption properties. This is referred to as chemical interference.

Interpretation Introduction

(k)

Interpretation:

The term radiation buffer needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

Radiation buffer is the interfering substance added in excess to avoid spectral interferences.

Explanation of Solution

Radiation buffer is a substance which when added in large quantities to the sample as well as standards prevents spectral interferences. For the interfering substance to act as radiation buffer, it needs to be added in excess quantities.

Interpretation Introduction

(l)

Interpretation:

The term solute volatile interference needs to be defined.

Concept introduction:

Atomic absorption spectroscopy is a way of quantitatively determining the chemical elements by using light absorption by free metallic ions.

Answer to Problem 9.1QAP

The aerosol particles volatilization rate change due to absence or presence of concomitant is solute-volatilization interference.

Explanation of Solution

In the presence of concomitant or in concomitant’s absence, when the analyte volatilization is not complete then the interference due to the dry aerosol particle volatilization rate changes, is referred to as Solute volatilization interference.