A new triazene-1-oxide derivative, immobilized on the triacetyl cellulose membrane as an optical Ni2+ sensor

An optical sensor for the direct measurement of Ni2+ ion was developed. The basic element of this optode is the immobilization of 1-p-tolyl-3-(3-(trifluoromethyl)phenyl)triaz-1-ene 1-oxide on a triacetyl cellulose membrane. Spectrophotometric studies of complex formation between the triazene-1-oxide derivative, L with Ni2+, Zn2+, Cu2+, Ag+, Co2+, Pb2+, Mn2+, Hg2+ and Cd2+ metal ions in acetonitrile solution indicated a substantially larger stability constant for the Nickel ion complex. Consequently, the new triazene-1-oxide derivative L was used as an appropriate ionophore for the preparation of a selective Ni2+ optical sensor, by its immobilization on a transparent triacetyl cellulose tapes. The effects of pH, reagent concentration and reaction time on the immobilization of L were studied. A linear response curve was observed for the membrane sensor in Ni2+ concentration range of 1.18 × 10−9–7.34 × 10−5 M with a R2 value of 0.998 at pH 5.7. The detection limit (3σ) of the method for Ni2+ was 1.0 × 10−9 M. No significant interference from 100 times concentrations of a number of potentially interfering ions was observed for the nickel ion determination. The sensor showed a good durability and short response time with no evidence of reagent leaching. The sensor was successfully applied for the determination of Ni2+ in environmental water samples.