This is a Quantitative Analysis Chemistry questios; 1) Analysis for potassium by

Question

This is a Quantitative Analysis Chemistry questios;

1)

Analysis for potassium by atomic absorption spectroscopy yielded a detector signal (proportional to concentration) of 110.2 when a sample was aspirated into the plasma and 0.7 when water (i.e. blank) was aspirated. After a small amount of NaCl was dissolved in the sample, the detector signal increased to 133.6 when the sample was aspirated whereas the blank measurement remained at 0.7. What is the most likely cause of the increased detector signal?

Sodium acted as an ionization suppressor

Sodium absorbs at the same wavelength as potassium

Sodium transferred energy to potassium atoms, creating more excited state species

Sodium formed an oxide in the flame

2)

Which of the following are advantages of atomic emission spectroscopy compared to atomic absorption spectroscopy? Select all that are appropriate.

Higher temperatures permit analyses of elements that are difficult to atomize

Fewer spectral interferences

Lower operating costs

Simultaneous multielement analysis

Sodium acted as an ionization suppressor

Sodium absorbs at the same wavelength as potassium

Sodium transferred energy to potassium atoms, creating more excited state species

Sodium formed an oxide in the flame

2)

Which of the following are advantages of atomic emission spectroscopy compared to atomic absorption spectroscopy? Select all that are appropriate.

Higher temperatures permit analyses of elements that are difficult to atomize

Fewer spectral interferences

Lower operating costs

Simultaneous multielement analysis

Explanation / Answer

1.Sodium acted as an ionization supressor so that atomic absorption increased. Determination of alkalimetals like soium and potassium by Atomic absorption method is not recommended due to higher ionization effect ( less ionization energy ) and lower sensitivity. Alkali metals are well determined by flame emission spectrometers.

2. a) Higher temperture permits analysis of elements that are difficult to atomize in atomic absorpion spectroscopy

b)simultaneous multi element analysis is big atvantage of Atomic emission spectroscopy

Spectral interferences is one of the disadvantage of atomic mission spectroscopy

If no of element to be determined per sample is less then atomic absorption spectroscopy is cost effective but no of element to be determined per sample is higher then atomic emission spectroscopy is cost effective

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