Zetium Polymers edition
The analysis of cadmium and other elements of environmental concern is described in the EU directive on the Restriction of Hazardous Substances (RoHS 2). These regulations affect a wide range of goods, many comprising plastics and polymers. This data sheet demonstrates that the Zetium Polymers edition together with the TOXEL standards is an effective solution for the analysis of environmentally sensitive heavy elements in polyethylene.
The Zetium Polymers edition is a fully integrated wavelength dispersive XRF analyzer, consisting of a spectrometer, X-Y sample handler and software.
The Zetium Polymers edition has been especially configured to meet the needs of the plastics and polymers industry. Designed to provide accuracy, precision and sub-ppm detection limits for many elements, the Zetium Polymers edition with the unique SuperQ software provides high-quality data in both production control and R&D environments.
TOXEL is a set of standards for the calibration of toxic heavy elements in polyethylene. These standards were developed in close collaboration with DSM Resolve, a polymer R&D laboratory with considerable experience in the development of polymer standards and the quantitative analysis of trace elements
in plastic products. TOXEL is an optional module for Zetium Polymers edition and consists of:
- 4 standards + 1 blank
- Elements: Cr, Ni, Cu, Zn, As, Br, Cd, Ba, Hg, Pb
- Pressed discs (~2 mm x 40 mm)
- 2 replicates for each standard
- Certificate of composition (see Table 1)
The SuperQ software for the Zetium Polymers edition contains an application template for this TOXEL application and setup only requires the measurement of the standards. The measurement times used to obtain the data presented in this data sheet are given in Table 2.
Table 1. Concentration of elements in the TOXEL certified reference materials
Table 2. Total measurement time (peak + backgrounds). Ti* is a channel required for line overlap
Table 3. Analytical precision
Precision and instrument stability
The precision, repeatability and reproducibility of the Zetium Polymers edition system are excellent, not only for short-term measurements (15 consecutive measurements, Table 3), but also for longer periods (8 measurements carried out over a period of 10 days). For comparison the counting statistical error (CSE in ppm) is also shown in Table 3.
The accuracy of the calibrations is presented in Table 4. The calibration RMS values are a statistical comparison (1 sigma) of the certified chemical concentrations of the standards with the concentration calculated by regression in the calibration procedure.
Detection limits typical for the elements of interest in polymer matrices are given in Table 5. The lower limit of detection (LLD) is calculated from:
Table 4. Calibration quality and accuracy
Table 5. Detection limits (The LLD values quoted are typical for the prepared polymer samples, LLD values for individual samples will vary according to the composition of the sample matrix).
The results clearly demonstrate that the Zetium Polymers edition spectrometer can analyze heavy elements in polymers samples down to sub-ppm levels.
The stability of the Zetium Polymers edition is such that individual calibrations can be used for many months. Time-consuming re-standardizations are unnecessary and the resulting data are highly consistent over time.