High-Precision, Simultaneous Analysis of Pt, Pd, and Rh in Catalytic Converter Samples by Carius Tube Dissolution and Inductively Coupled Plasma Atomic Emission Spectroscopy with Charge-Injection Device Detection

Abstract

A robust method of analysis that uses multichannel array detector technology is presented for high-precision, accurate measurement of Pt, Pd and Rh in catalytic converters. Catalytic converter samples, National Institute of Standards and Technology (NIST) reference standards, and a fresh converter sample are dissolved and analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Complete dissolution of sample sizes up to 2 g of NIST reference standards is achieved with the use of high-pressure, high-temperature carius tubes. Carius tube dissolution of a modern catalytic converter sample is found to be incomplete because of the presence of higher concentrations of Ce, Ni, and Zr. For this sample, the addition of FeCl3 increases the dissolving power of the carius tube for base metals and noble metals, particularly Rh. Although interference problems are encountered in samples bearing high concentrations of Fe, use of a high-resolution ICP-AES system alleviated these problems. Precise quantitation of Pt, Pd, and Rh is accomplished by using the method of standard additions, with high accuracy and a precision of 1–2% RSD (relative standard deviation). This analysis also confirmed the values determined by NIST by using isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) for standard reference materials (SRMs) 2556 and 2557.