Determination of zirconium traces in polymers by ICP-IDMS – a powerful and fast method for routine testing of zirconium residues in polyolefins

Abstract

Zirconium trace analyses play an important role for polyolefins produced by modern catalytic processes with zirconium metallocenes. A reliable and fast routine testing method by inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) was therefore developed, which allows the determination of zirconium in polymers down to the low ng/g level. With respect to its precision, accuracy, and time-consumption this method is suitable for routine testing of production processes. A spike solution, enriched in the stable isotope ⁹¹Zr, was prepared and used for the isotope dilution procedure, which has the advantage of being an internal “one point” calibration method. The polyolefin samples were dissolved by microwave assisted digestion with a mixture of concentrated HNO₃/HF.