The determination of palladium under microgram concentration levels is generally hampered by insufficient sensitivity of the techniques used and or by a matrix effect. With the introduction of techniques, sensitivity problems have been drastically reduced.There are chemical and physical methods to increase the sensitivity and decreasing matrix effects, such as extraction 1,2 or preconcentration by solvent evaporation; however, in the presence of complex matrices with very low concentration of the analyte, these methods are seldom effective and are considered to be unsatisfactory. However, the development of a sensitive, accurate, precise and fast procedure using less sophisticated instruments is a vital process.The formation of extractable chelates of Pd(II) with dithizone 3 and dithiocarbamate 4 has been applied to the separation of Pd(II) from other platinum metal ions. Also, the extraction of Pd(II) halide complexes affords convenient separation.5 Oxime derivatives have also been used for extraction and the spectrophotometric determination of Pd(II).Flotation techniques are recommended as good separation and preconcentration 6-8 tools with most of the advancing factors previously mentioned. Recently, the flotation-separation step can be analytically completed spectrophotometrically 9 or by a suitable technique, such as atomic absorption spectrometry. 10 Such techniques acquire analytical importance as the flotation-separation step is selectively completed.Although many spectrophotometric methods have been reported for the determination of Pd(II) 6-8 , a simple, rapid and economical flotation-spectrophotometric method has been developed for the concentration and determination of trace Pd(II) in different matrices using HOL as a surfactant and HHB as a chelating reagent. This reagent is more sensitive and specific than many of the reagents reported for Pd(II). 3,4 Moreover, this method involves the determination of trace Pd(II) after selective separation by floatation, those eliminating the effect of foreign ions and increasing the sensitivity. Also, the direct determination of Pd(II) in the surfactant phase decreases its determination time and loss during the determination. Another advantage of the present investigation is that the data obtained spectrophotometrically were attained by the simplest colorimetric analysis method.A literature survey showed that ion-flotation followed by a spectrophotometric determination of Pd(II) is rarely reported.11,12 Also, no attempt has been found for using HHB in this concern. Fortunately, in this investigation, HHB finds its role for a direct spectrophotometric determination of Pd(II), and also gives high performance in the preconcentration of Pd(II) via its flotation as HHB-Pd colligend.
Experimental
ReagentsPalladium stock solutions were prepared by dissolving 1 g PdCl 2 (Merck) in 3 ml HCl followed by dilution to 250 ml using doubly distilled water or ethanol. For the analysis of simulated ores, a Pd stock solution was prepared by dissolving 1 g of Pd wire in few ml of ...