ABSTRACT

''Validation of an analytical method with modified acid purity and iron matrices to measure heavy metals (Cd, Pb, Cr and As) in fertilizers''. Introduction: The frequent use of fertilizers in the Costa Rican agricultural sector causes environmental pollution; and heavy metals are among the main pollutants because of their high toxicity, strengthening the need for affordable and reliable local methods to assess pollution levels. Objective: To validate an adaptation of a method that uses modified acid purity and iron matrices to measure heavy metals (Cd, Pb, Cr and As) in fertilizers. Method: We tested four duplicate analyzes of a sample of known concentration with reactive grade acids and ultra-pure acids. For the iron interference test, we used eight replicates. We also did tests for bias, precision, detection limits, quantification limit, specificity, recovery, false positives and false negatives. Results: The new method proved satisfactory and its efficiency held by analytical performance parameters. Conclusions: The method is resistant to changes in acid purity, and tolerates matrices with iron concentrations under 5% m/m.

Keywords: Heavy metals; fertilizer; agrochemicals; validation; ICP