Page 182 - An Introduction to Analytical Atomic Spectrometry - L. Ebdon

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media is based on the characteristic spectra that sodium emits upon being aspirated into an air-acetylene
flame.

B.4.2 Objectives

1 To investigate the effect of potassium on the analysis of sodium by atomic emission spectrometry.

2 To quantify sodium in a soil extract using calibration standards.

B.4.3 Instrumentation and Reagents.

1 Atomic absorption/atomic emission spectrometer with air-acetylene burner head. Pressurized
acetylene cylinder. Air compressor.

2 Sodium stock solution.
3 Potassium stock solution.

4 Ammonium chloride (1 mol 1 ).
-1
5 Soil extract.

6 Using distilled or de-ionized water prepare six standards in 100 ml volumetric flasks containing 10
µg ml sodium and 500, 100, 50, 25, 10 and 0 µg ml potassium. Also prepare a 250 ml standard
-1
-1
containing 10 µg ml sodium and 1000 µg ml potassium.
-1
-1
7 Using distilled or de-ionized water prepare five standards in 100 ml volumetric flasks containing 0.5
mol 1 ammonium chloride, 1000 µg ml potassium and 10, 8, 5, 2 and 0 µg ml sodium.
-1
-1
-1
8 Using distilled or de-ionized water prepare a sample for analysis by pipetting 25 ml of the unknown
soil extract into a 50 ml volumetric flask and adding an appropriate volume of potassium stock solution
-1
to give a final concentration of 1000 µg ml .
B.4.4 Procedure

NOTE: Solution (either water or sample) must be continuously aspirated into the flame. Therefore,
ensure that the sample delivery tube is immersed in solution at all times. Rinse all glassware with
distilled or de-ionized water before preparing standards to avoid sodium contamination. Ensure that you
have prepared all of your standards before proceeding with the experiment.

1 Switch the spectrometer on and allow to warm up for 10 min.

2 Ensure that an air-acetylene burner head is fitted.