This application note demonstrates that Zetium with the addition of TOXEL Certified Reference Materials (CRMs), is an effective solution for the analysis of Cr, Ni, Cu, Zn, As, Br, Cd, Ba, Hg and Pb in polyolefins (PE and PP types).
Several of these elements are of environmental concern and described in several regulation like RoHS, REACH and others.
This data sheet demonstrates that Zetium with the addition of TOXEL Certified Reference Materials (CRMs), is an effective solution for the analysis of Cr, Ni, Cu, Zn, As, Br, Cd, Ba, Hg and Pb in polyolefins (PE and PP types). Several of these elements are of environmental concern and described in regulations like RoHS, REACH and others.
In collaboration with DSM Resolve a set of certified reference materials was developed for the analysis of catalysts residues and potentially toxic elements in polyethylene (TOXEL). The TOXEL set consists of 5 different standards including a blank, with 4 discs of each standard. The standards cover the elements and concentration ranges normally required for the analysis of important catalyst and potentially toxic elements in plastic and polymers, such as Cr, Ni, Cu, Zn, As, Br, Cd, Ba, Hg and Pb.
This study was performed using the wavelength dispersive optics of the Zetium XRF spectrometer. It was configured with a 1 kW Rh anode SST R tube and is a fully integrated system with a X-Y sample handler and state-of-the-art SuperQ software, featuring an advanced Fundamental Parameters algorithm. The Zetium spectrometer is engineered for excellence in terms of both analytical accuracy, precision and operational performance.
Table 1. Measurement times (peak + background)
Before the measurements, all TOXEL discs were cleaned with de-ionized water and dried with soft laboratory paper. A 20 minute measuring program was used and total measurement time, peak and background, for each element are presented in Table 1.
The accuracies of the calibrations are presented in Table 2. The calibration RMS value is the statistical comparison (1 sigma) of the certified chemical concentration of the CRMs with the concentrations calculated by regression in the calibration procedure.
Table 2. Concentration range and accuracy
A calibration plot for Pb gives a graphic illustration of the accuracy of the method, Figure 1.
Figure 1. Calibration graph of Pb
The repeatability and reproducibility of Zetium are very good, not only for short-term measurements, but also for longer periods. For comparison the counting statistical error (CSE in mg/kg) is also shown in Table 3. The CSE is theoretically the minimum possible error and the data demonstrate the inherent stability of the Zetium spectrometer.
Table 3. Analytical precision
Detection limits typical for elements of interest in polymer products are listed in Table 4.
The long-term stability of the Zetium spectrometer is illustrated by measurements carried out for 14 days, Figure 2.
Table 4. Detection limits
Figure 2. Repeatability results of Br and Pb in a TOXEL standard
The Zetium spectrometer enables the accurate and repeatable measurement of elements of environmental concern in polymer and plastic products ranging from virgin polymer to recycled plastics. Being capable of performing these measurements at relatively low concentration levels, the Zetium spectrometer becomes an ideal instrument for quality control and analysis of catalyst residues and potentially toxic elements in polymers and plastics.
The results clearly demonstrate the capability of the Zetium spectrometer for the analysis of Cr, Ni, Cu, Zn, As, Br, Cd, Ba, Hg and Pb in polyethylene. Combined with TOXEL, Zetium is designed to meet the demands of the plastic and polymer industry.
