Determination of lead in organic-inorganic compound fertilizer by hydride atomic absorption spectrometry

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Determination of Lead in Organic-Inorganic Compound Fertilizer by Hydride Atomic Absorption Spectrometry

This study presents a reliable and efficient method for determining lead content in organic-inorganic compound fertilizers using hydride atomic absorption spectrometry. Compared to traditional methods like flame photometry or graphite furnace techniques, this approach offers better sensitivity, selectivity, and faster analysis times. The method involves flow injection hydride generation combined with atomic absorption spectroscopy, enabling automated operation and accurate quantification. The experimental setup includes an AA-1800C atomic absorption spectrophotometer and a WHC-102A2 flow injection hydride generator. A lead standard solution was prepared at 1000 mg/L, and potassium borohydride was used as a reducing agent. Iron solution served as an oxidant to convert Pb²⁺ into Pb⁴⁺, ensuring complete reaction. The system's conditions were optimized for carrier gas flow rate, working voltage, and acidity levels to achieve maximum absorbance and stability. Key parameters such as the concentration of iron, oxidation time, and hydrochloric acid volume were carefully evaluated. It was found that 10 mL of 80 g/L iron solution provided optimal oxidation, while 20 minutes was sufficient for complete reaction. The carrier gas flow rate was set at 150 mL/min, and the quartz tube operated at 100 V. The potassium borohydride solution was maintained at 20 g/L, with 0.4 g of sodium hydroxide added per 100 mL to stabilize the reaction. Linear calibration curves showed a strong correlation between lead concentration and absorbance in the range of 0–30.0 ng/mL, with a detection limit of 0.2 ng/mL. Interference studies confirmed that common ions such as K⁺, Mg²⁺, Ca²⁺, Fe³⁺, Cu²⁺, Cr³⁺, Zn²⁺, and B³⁺ did not significantly affect the results when their concentrations were within acceptable limits. Precision and accuracy tests demonstrated good repeatability, with RSD values ranging from 2.6% to 4.6%, and recovery rates between 96.4% and 104.3%. These results confirm the method’s reliability for routine analysis in complex matrices. Overall, the proposed technique is simple, fast, and highly effective for lead determination in organic-inorganic compound fertilizers. Key words: hydride atomic absorption spectrometry; inorganic compound fertilizer; AA-1800.