Analytical Chemistry Chapter 3: Atomic Spectroscopy

Atomic spectroscopy methods are categorized based on the ______ of atomization.

What is atomization?

Which of the following are factors that contribute to atomic spectral line widths?

The atomization process is the 'signal generator', meaning it produces the signal that is measured in atomic spectroscopy.

Which of the following are common atomization spectroscopic methods?

What are the advantages of using a flame atomization method?

In the flame atomization method, the fuel/oxidant mixture affects the atomization temperature, meaning that different mixtures can be used to achieve different temperatures.

The ______ of a flame is a region where the primary combustion occurs, leading to the initial breakdown of the sample.

The ______ of a flame is a region where secondary combustion takes place, contributing to further breakdown of the sample and generation of atomic species.

Explain the process that occurs in the inner cone region of a flame.

In the graphite furnace atomization method, the atomization process and temperature are rigorously controlled using a series of heating steps, enabling optimized atomization and increased sensitivity.

What are the advantages of using a graphite furnace method for atomization?

The atomization process in inductively coupled plasma (ICP) is achieved by using plasma, which is a high-temperature, ionized gas.

In the ICP atomization method, how does the sample interact with the plasma to achieve atomization?

What happens to the ions in the ICP atomization method?

Atomic emission spectroscopy (AES) is a technique that measures the intensity of ______ emitted by excited atoms.

Explain what atomic emission is.

In atomic emission spectroscopy, the intensity of the emitted light is proportional to the concentration of analytes in the sample.

Explain the different stages of flame emission spectroscopy.

Flame photometers are equipped with a nebulizer and a burner, which together form a single unit.

Which of the following are advantages of using turbulent flow burners?

What are the disadvantages of using turbulent flow burners?

In direct insertion, the sample is introduced directly into the ______.

What are the advantages of using premix (laminar flow) burners?

The disadvantage of using a premix burner is that it has a lower rate of sample introduction, potentially reducing the accuracy of sample representation in the flame.

What is the purpose of a wavelength selector?

Filters are used to select specific wavelengths in atomic emission or absorption spectroscopy.

The narrowness of the bandwidth results in ______ resolution.

What is the main purpose of a detector in atomic spectroscopy?

What are some commonly used light sensors in atomic spectroscopy?

A detector is typically attached to an amplifier and an analog or digital readout device to process and display the measured signal effectively.

Atomic absorption spectroscopy (AAS) is a technique that measures the absorbance of light by ground state atoms.

What are the basic components of an atomic absorption spectrophotometer?

The line source in AAS is a source of light that emits specific wavelengths corresponding to the analyte of interest.

What are the two main types of light sources commonly used in AAS?

Hollow cathode lamps (HCL) are filled with an inert gas that is ionized using an applied potential of ~300 V DC, leading to the sputtered atoms of the analyte that produce light at specific wavelengths.

Explain how a hollow cathode lamp works.

Electrodeless discharge lamps (EDL) work on the principle of using a radio frequency or microwave field to excite atoms of the analyte within a sealed quartz tube, leading to the emission of light at specific wavelengths.

EDL lamps are generally more intense than HCL lamps, offering better sensitivity and making them a preferred choice for certain applications.

The disadvantage of EDL lamps is that they are unstable and only available for about 17 metals.

A chopper in atomic absorption spectroscopy is a rotating device that modulates the light beam from the hollow cathode lamp, helping to distinguish between the analyte's light absorption and background noise.

What is the purpose of background correction in atomic absorption spectroscopy?

In atomic absorption spectroscopy, the monochromator is a component that is placed between the flame and the detector.

What is the primary role of the monochromator AAS?

Monochromators are typically made up of three parts: an entrance slit, a dispersing element, and an ______ slit.

What are some common examples of dispersing elements used in monochromators?

What is the role of the detector in AAS?

What are the main types of detectors used in AAS?

The main advantage of AAS is its ability to determine the concentration of over 60 elements in a sample, making it a widely used technique in various analytical applications.

AAS is also known for its speed of routine analysis, as measurements can be performed quickly.

Another advantage of AAS is its minimal clogging problems, making it a reliable technique with reduced downtime.

The main disadvantage of AAS is its lower sensitivity compared to other methods, such as flame photometry, limiting its application for analyzing very low concentrations of analytes.

What are the main types of interferences common in atomic spectroscopy?

Blank interferences refer to interferences that are caused by the sample matrix itself, while analyte interferences are caused by the analyte's interaction with the sample matrix.

What are the main types of analyte interferences?

Spectral interferences occur when the absorption or emission spectra of an interfering species overlaps or lies close to that of the analyte.

Physical interferences are mainly caused by changes in the viscosity of the sample due to the presence of certain substances, which can influence the flow rate and nebulization efficiency.

Chemical interferences arise when species present in the sample matrix interact with the analyte, modifying its atomization behavior and affecting its signal.

During chemical interferences, the presence of certain species in the sample matrix can either enhance or decrease the volatility of the analyte, significantly impacting its atomization and influencing the analysis.

Ionization interferences arise when the presence of easily ionized elements, such as alkali and alkaline earth metals, in the sample can alter the ionization behavior of less-easily ionized elements, influencing the analysis.

One common solution to manage ionization interferences is to use ionization suppressants, which are elements that have a lower ionization potential than the analyte, suppressing the ionization of the analyte and improving the accuracy of the analysis.

When using a hotter flame in atomic spectroscopy, the analyte is more likely to be atomized, reducing the effect of chemical interferences.

Protective agents are compounds that form stable but volatile complexes with analyte ions, preventing them from interacting with the sample matrix and reducing the potential for chemical interferences.

Releasing agents are compounds that preferentially react with interfering anions, preventing them from inhibiting the atomization of the analyte, and improving the accuracy of the analysis.