2-hydroxy-1-naphthaldehyde-p-hydroxy benzoic hydrazone (HNHBH) is used as a new analytical reagent for the direct and derivative spectrophotometric determination of yttrium (III). It reacts with yttrium in basic medium (pH 8.5, ammonium chloride and ammonium hydroxide buffer) to form yellow colored (λ max, 410 nm) 1:4 (Y- HNHBH) complex. The colour reaction is instantaneous and the absorbance remains constant for about 24h. The molar absorptivity and Sandall’s sensitivity were found to be 6.76 x 104 L mol-1cm-1 and 0.0013 μg cm-2 respectively. The system obeys Beer’s law in the range of 0.044-2.222 μg mL-1 of Y (III). Tolerance limits of various foreign ions were also studied. The complex was fairly stable (stability constant 2.28 x 1022) and Second and third order derivative spectrophotometric methods were also developed for the determination of yttrium (III) which showed greater sensitivity and selectivity. The proposed method was applied for the determination of yttrium (III) in some nickel based alloy samples and in certain geological samples. The method has high sensitivity, selectivity precision and accuracy.
