Making analytical chemistry simpler by rediscovering cheap analytical reagents: Micro-spectrophotometric determination of palladium in catalysts using the food additive dye (yellow-6)

Simple spectrophotometric and extracto-spectrophotometric micro-methods have been developed in order to assess quality control in palladium catalysts by means of a cheap soft drink additive dye (yellow-6, Y6). In the pH range of 3 to 9.5, Y6 forms a red colored complex with Pd(II) with a maximum at 553 nm and a molar absorptivity of 1.14 x 104M-1 cm-1 at pH 7.0. The ratio of the metal ion to the ligand and its stability constant were found to be 1:2 and 3.92 x 1011, respectively. Extraction of the complex was carried out with the cationic surfactant Aliquat-336 by using methyl isobutyl ketone as organic solvent. The effect of pH, ionic strength, organic phase volume, Y6 and surfactant concentration on complex formation was studied, and the tolerance limits for many cations have been determined. Finally, the micro-methods were successfully applied to determine palladium content in commercial catalyst samples by using a commercial drinking soda containing Y6.