A critical evaluation of the performance of triphenylphosphine and N,N' -diphenylthiourea in solvent extraction concentration of precious metals for ICAP-AES analysis
In view of the capability of Inductively Coupled Argon Plasma-Atomic Emission Spectrometry (ICAPAES) for simultaneous multi-element analysis group extraction of trace elements is of special importance. Group extraction of precious metals using the complexing agents N, N'-diphenylthiourea (DPTU)and triphenylphosphine (TPP) was systematically investigated. From the results it appeared that platinum, palladium, gold and silver were selectively extracted as a group without the need of a labilizing agent. Direct ICAP-AES analysis of the organic extracts turned out to be feasible, but experimentally the analysis of organic solutions was much less straightforward compared to aqueous solutions. A procedure was tested to transfer the metals back into aqueous solution. The extraction procedure using both DPTU and TPP in solvent extraction of precious metals for ICAP-AES analysis has been applied to a certified platinum ore. The results showed a good agreement with the certificate.