Selection and Optimization of Methods for Analyzing Available Cadmium in Farmland Soils

Purpose To accurately measure the available cadmium (Cd) content in contaminated farmland soils and efficiently predict the Cd content in the edible parts of crops.

Methods Based on the original ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA) extraction method, an orthogonal experimental design was used to optimize three extraction conditions: pH of the extractant, volume added, and extraction time. The optimal conditions were determined, and the optimized method was validated by fitting the migration effects of Cd in the soil-crop system through field sampling and indoor pot experiments.

Results The optimal conditions for extracting available Cd using the optimized AB-DTPA method were: extractant volume of 50 mL, pH 7.0, and oscillation time of 60 minutes. The optimized AB-DTPA method provided the best prediction of Cd uptake in the edible parts of crops. The relative standard deviation of the Cd extraction results was less than 20%, with a spiked recovery rate ranging from 100.00% to 115.00%.

Conclusion The optimized AB-DTPA method is suitable for analyzing available Cd in contaminated farmland soils and predicting Cd uptake in the edible parts of crops. It is feasible, widely applicable, and accurate, meeting the requirements for batch analysis of available Cd.