Determination of Trace Elements in Imported Fertilizer by Atomic Absorption Spectrophotometry - Master's thesis - Dissertation

Determination of Trace Elements in Imported Fertilizer by Atomic Absorption Spectrophotometry

Key words: atomic absorption spectrophotometry; trace elements;

This standard outlines a method for determining trace elements such as copper, zinc, iron, manganese, and magnesium in imported fertilizers using atomic absorption spectrophotometry. The procedure involves dissolving the sample in nitric acid or hydrochloric acid, followed by analysis under specific conditions.

1 Method Summary

The sample is dissolved in nitric acid or hydrochloric acid, and the resulting solution is analyzed in an atomic absorption spectrophotometer. The elements are measured at specific wavelengths (e.g., 324.7 nm for copper, 213.9 nm for zinc, 248.3 nm for iron, 279.5 nm for manganese, and 285.2 nm for magnesium) using an air-acetylene flame.

2 Instrument

The AA-1800C atomic absorption spectrophotometer, equipped with an air-acetylene burner and hollow cathode lamps for copper, zinc, iron, manganese, and magnesium, is used. The instrument should meet the following performance criteria: minimum sensitivity, working curve linearity, and minimum stability.

3 Reagents

3.1 Hydrochloric acid (1+1).

3.2 Nitric acid (1+1).

3.3 Barium chloride solution (0.1%).

3.4 Zinc standard stock solution (1 mg/mL).

3.5 Zinc standard solution (10 µg/mL).

3.6 Copper standard stock solution (1 mg/mL).

3.7 Copper standard solution (10 µg/mL).

3.8 Iron standard stock solution (1 mg/mL).

3.9 Iron standard solution (100 µg/mL).

3.10 Manganese standard stock solution (1 mg/mL).

3.11 Manganese standard solution (10 µg/mL).

3.12 Magnesium standard stock solution (1 mg/mL).

3.13 Magnesium standard solution (10 µg/mL).

4 Procedure

4.1 Preparation of Test Solution: Weigh 1 g of the sample and dissolve it in 15 mL of hydrochloric acid. Boil until the volume reduces to 2–4 mL, then dilute to 100 mL with water.

4.2 Measurement of Zinc, Copper, Iron, and Manganese: Measure the absorbance at the respective wavelengths using the atomic absorption spectrophotometer. Compare with standard solutions to determine concentrations.

4.3 Measurement of Magnesium: Dilute the sample with barium chloride and hydrochloric acid, then measure absorbance at 285.2 nm.

4.4 Preparation of Working Curves: Prepare standard series for each element, measure absorbance, and plot the working curves.

5 Calculation of Results

The concentration of each element is calculated using the working curve. The formula takes into account the concentration from the curve, the volume of the solution, and the mass of the sample.

Key words: atomic absorption spectrophotometry; trace elements;