A new spectrophotometric method for determination of EDTA in water using its complex with Mn(III)

• New reagent for direct determination of EDTA by formation of highly colored Mn(III)-EDTA complex.
• A low limit of detection for EDTA determination was obtained using immobilized PbO2 solid reagent and Mn(II).
• Proposed a very simple procedure for preparation of PbO2 solid reagent with cyanoacrylate glue.
• Optimization of method using a 2 variables-Doehlert matrix.

EDTA is an important ligand used in many industrial products as well as in agriculture, where it is employed to assist in phytoextraction procedures and the absorption of nutrients by plants. Due to its intensive use and recalcitrance, it is now considered an emerging pollutant in water, so there is great interest in techniques suitable for its monitoring. This work proposes a method based on formation of the Mn(III)-EDTA complex after oxidation of the Mn(II)-EDTA complex by PbO2 immobilized on cyanoacrylate spheres. A design of experiments (DOE) based on the Doehlert matrix was used to determine the optimum conditions of the method, and the influence of the variables was evaluated using a multiple linear regression (MLR) model. The optimized method presented a linear response in the range from 0.77 to 100.0 μmol L− 1, with analytical sensitivity of 7.7 × 103 L mol− 1, a coefficient of determination of 0.999, and a limit of detection of 0.23 μmol L− 1. The method was applied using samples fortified at different concentration levels, and the recoveries achieved were between 97.0 and 104.9%.

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