title: Evaluation of colour quality of complexometric indicators in the titration of Nickel(II) with EDTA by tristimulus colorimetry.
abstract: Trichromatic colorimetry was applied to the specification of colour changes of metallochromic indicators viz., murexide, pyrocatechol violet, bromopyrogallol red, pyrogallol red and chromazurol S in the complexometric titration of Nickel(II) with ethylene-diaminetetraacetic acid (EDTA), in order to assess the quality of colour change at the equivalence point with the help of CIE L*a*b* 1976 system and the values of SCD (Specific Colour Discrimination) parameter. A screened indicator, a mixture of murexide and methylene blue in the ratio 10:1 (m/m), is proposed as an ideal indicator in this titration as evidenced by the plots of a* vs. b* and from the numerical values of standard deviation for a large number of visual titrations.
authors.affiliation: School of Chemistry, Andhra University, Visakhapatnam 530 003, India.
authors.forename: S
authors.initials: S
authors.lastname: Raheem
authors.forename: K M
authors.initials: KM
authors.lastname: Prasad