Determination of aluminium phosphide (AlP) in fumigants by ICP OES

Abstract

A method for determination of aluminium phosphide (AlP) in fumigants by inductively coupled plasma optical emission spectrometry (ICP OES) is presented. An 8 hour hydrolysis in water achieved complete decomposition of AlP, with the released PH₃ being absorbed in a medium of KMnO₄/H₂SO₄. The solution was treated with NH₂OH·HCl to reduce the excess MnO₄⁻ and the PO₄³⁻ so formed was quantitated as P by ICP OES based on external calibration using the P(I) 213.618 nm emission line. A detection limit (3s, n = 10) of 0.26 g/100 g AlP and an LOQ (10s, n = 10) of 0.85 g/100 g AlP were realized. Ten commercial samples of fumigants were analysed, providing results in agreement with specifications of ∼55–60 g/100 g and concordant with values generated by a spectrophotometric method, as evidenced by a paired t-test (95% confidence limit). This simple procedure has been adopted by the Paraná Institute of Technology – TECPAR (Curitiba, Brazil).