Study of the use of soil suspensions in the determination of iron, manganese, magnesium and copper in soils by flame atomic-absorption spectrometry

Abstract

A method is described for the direct, routine atomic-absorption spectrometric determination of copper, iron, manganese and magnesium in soil samples of the terra rossa and peat types. An investigation was made of the factors influencing the atomisation efficiency of these elements when suspensions of soil samples were aspirated into the flame. Particle size, flame temperature and position in the flame were found to be critical in determining the fractions of particular elements atomised. Special emphasis was given to the preparation of the soil suspensions, which is the most critical step in the whole analytical procedure. Magnetic and ultrasonic devices were used for stirring purposes. The latter proved to be more efficient, particularly when suspensions of high clay content soils are being prepared. An average standard sample made for each soil type was used for calibration. Test analyses of two sets of soil samples showed that the majority (80–90%) of samples can be analysed with an accuracy of ±20%. This should be acceptable in most applications where a large number of samples are to be analysed. Considerable amounts of time and chemicals can be saved. The method was also found to be suitable for the determination of lithium, calcium, strontium, barium, aluminium, chromium and titanium.