Novel catalytic fluorescence method for speciative determination of chromium in environmental samples

Abstract

Background: Thiourea derivatives act as promising chemosensors for sensing transition metal ions. 1-(2-hydroxyphenyl)thiourea (HPTU) is one such chromophore that has potential for metal ion sensing. The current investigation reports the sensing of chromium species using transition metal-oxo-based reaction of 1,2-hydroxyphenylthiourea. Methods: The catalytic effect of chromium (III) and chromium (VI) on the oxidation of HPTU was studied. The reaction was followed spectrofluorimetrically by measuring the fluorescence intensities of the reaction product at λex = 416 and λem = 520 nm, respectively. Results: Under the optimum analytical conditions, HPTU acts as a chromogenic sensor for the detection of chromium species in nano-gram levels with a determination range of 0.3 to 250 ng/mL. Conclusions: The methods are fairly sensitive, and the role of activators and sensitizers in enhancing the catalysis was studied. Interference due to various cations and anions in the experiment was investigated. The proposed method was applied to environmental samples for the analysis of chromium content.