Determination of the palladium content in a solid plastic material by electrothermal vaporization ICP-mass spectrometry (ETV-ICPMS)

Abstract

Electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICPMS) was used for the determination of the Pd content in a solid aliphatic polyketone. The presence of Pd in this material has to be attributed to the use of a Pd-containing homogeneous catalyst for its production. By application of a multi-step heating programme, the organic matrix could be selectively and completely removed prior to the vaporization of the analyte element. The accuracy attainable when using (i) external calibration and (ii) single standard addition using an aqueous standard solution was evaluated by comparison of the results obtained with a reference value obtained by means of neutron activation analysis (NAA). On the basis of its similar furnace behaviour, Ir was shown to be perfectly suited to be used as an internal standard. Also the argon dimer signal (Ar₂⁺) shows some potential to be used as an internal standard. When using Ir or Ar₂⁺ as an internal standard and single standard addition for calibration, the ETV-ICPMS result (∼5 µg g^–1) agreed within 10% with the NAA result on each occasion (deviation between average ETV-ICPMS result and reference value ∼2%). The absolute limit of detection (3s-criterion) was observed to be ∼1 pg, corresponding to a relative value of ∼1 ng g^–1, taking 1 mg as a typical sample mass. However, when using Ir as an internal standard, it was established that the detection limit deteriorated to ∼20 pg, due to the presence of a measurable amount of Pd in the Ir standard solution.