Spectrophotometric determination of Neodymium(III), Samarium(III), Gadolinium(III), Terbium (III), Dysprosium (III) , Holmium (III) in micellar media

Abstract

Spectrophotometric procedure for the determination of metal ion representatives from the three subgroups of lanthanide series, namely Neodymium (III) & Samarium (III) of Cerium group; Gadolinium (III) & Terbium (III) of Terbium family and Dysprosium (III) & Holmium (III) of Yttrium family has been studied using 1-(2-pyridylazo)-2-naphthol (PAN) as a chromogenic reagent in micellar media. The reported procedure avoids the use of carcinogenic molecular solvents. The method is based on the formation of an intense red colored ML₃ type of complex (L=PAN and M= Ln ³⁺) in the <i style="mso-bidi-font-style: normal">p</i>H range 8.5–9.5, soluble in all the three micellar media under study, viz. <span style="mso-bidi-font-size:11.0pt;letter-spacing:-.1pt" lang="EN-GB">Sodium dodecyl sulphate (SDS), <span style="mso-bidi-font-size:11.0pt;letter-spacing:-.1pt" lang="EN-GB">Cetyl trimethyl ammonium <span style="mso-bidi-font-size:11.0pt; letter-spacing:-.2pt" lang="EN-GB">bromide (CTAB) and Triton X-100. All the systems show (6.2 – 9.18) × 10⁴, (4.4 – 8.5) × 10⁴ and (4.3 – 7.8) × 10⁴ mol^-1 cm^-1 dm³molar absorptivity and (1.5 – 3.02) × 10^-4, (1.7 – 2.96) × 10^-4, (2.1 – 2.8) × 10^-4 <span style="font-family:Symbol; mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:"times="" roman";="" mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB">mg cm^-2 Sandell’s sensitivity for Triton X, CTAB and SDS respectively. The tolerance limits towards several foreign ions are also reported.

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