Study on the atomic absorption spectrochemical analysis with standard addition method

Abstract

The relationship between the concentration of the sample solution and the accuracy of atomic absorption spectrochemical analysis with standard addition method was studied.
The experiment was carried out on the determination of strontium in the presence of aluminum as an interfering element. Preliminary test showed that the absorbance of strontium was interfered by aluminum almost in proportion to the logarithm of the concentration, and the calibration curve for strontium deviated from Beer's law in the low-concentration region of strontium in the presence of small amounts of aluminum. In the atomic absorption spectrochemical analysis with standard addition method, the concentration of the element in question in the sample solution had been prepared so as to come within the linear range of the relative concentration vs. absorbance curve. However, the results of the present experiment showed that the higher the concentration of the interfering element in the sample solution, the higher the positive error.
From these results, it was found that the sample solution should be diluted enough prior to the analysis for the purpose of improving an accuracy of atomic absorption spectrochemical analysis with standard addition method, and the degree of dilution of the sample solution is able to decide as follows; the sample solution is diluted until the difference between the absorbance of the sample solution and that of the solution added a suitable amount of the element to be determined (for example, 1 ppm of strontium in the present experiment) to the sample solution coincide with the absorbance of the solution containing the same amount of the element which is added to the sample solution within the range of experimental error.