Highly selective and sensitive chromium(III) membrane sensors based on 4-amino-3-hydrazino-6-methyl-1,2,4-triazin-5-one as a new neutral ionophore

A poly vinyl chloride membrane sensor for chromium(III) ions was prepared based on 4-amino-3-hydrazino-6-methyl-1,2,4-triazin-5-one (AHMTO) as a membrane carrier. The sensor has a linear dynamic range of 1.0 × 10−6 to 1.0 × 10−1 M, with a Nernstian slope of 19.7 ± 0.3 mV decade−1, and a detection limit of 5.8 × 10−7 M. It has a fast response time of <10 s and can be used for at least 3 months without any considerable divergences in its potentials. The proposed sensor revealed comparatively good selectivity with respect to most alkali, alkaline earth, some transition and heavy metal ions, and could be used in a pH range of 2.7–6.6. It was successfully used as an indicator electrode in potentiometric titration of Cr(III) with EDTA and also to the determination of Cr(III) in wastewaters of chromium electroplating industries.