Feb/March_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 2 1 2 8 the more elements are included, and the more interference is encountered. Sample dilution reduces interference levels but also reduces sensitivity, di- minishing the key driver behind ICP-MS technology. ICP-MS has several other draw- backs too. First, sample preparation re- quires expensive high-purity diluting acids. In addition, the highly sensitive technique means that the smallest level of contamination can invalidate results meaning that the equipment needs to be cleaned and tests re-run. Further- more, cleanroom conditions and strict cleaning protocols are a must, add- ing time and cost to each analysis. In a commercial laboratory requiring high throughputs with optimal reproducibil- ity and accuracy, labor-intensive, ex- pensive, and specialist processes can have substantial, negative impacts. For a sustainable future, where REEs are detected and recovered quick- ly and effectively, the manual and costly processes of the past must be challenged. New techniques must be explored to increase throughput while maintaining high sensitivity and quality standards. Reproducibility and accura- cy are key criteria needed for reuse and recycling to become a viable alternative to mining virgin ore. ICP-OES: A SIMPLE ALTERNATIVE Recent advances in ICP-OES tech- nology are providing an alternative analytical option to ICP-MS at a low- er capital outlay. Advanced instru- ments such as the Thermo Scientific iCAP PRO XP ICP-OES Duo can now pro- vide similar detection rates and sam- ple throughputs when compared to ICP-MS, alongwith a high linearity range and very good spectral resolution, even in complex matrices. This new breed of ICP-OES takes the high matrix tolerance of radial ICP-OES systems and com- bines it with the sensitivity of axial ICP-OES technology to create a com- bined system that delivers both. With the addition of next generation inter- element correction software, interfer- ence can be removed automatically, enabling the resolution of overlapping wavelengths. Interelement correction is only the first step in automating workflows. ICP-OES software is designed to support ease of operation, with instrumentation control managed entirely through the software. Start-up, calibration, perfor- mance checks, and maintenance alerts are automated through a series of elec- tronic workflows, thereby freeing tech- nicians to complete specialist tasks, protecting the method from human er- ror, and increasing reproducibility. Although the analysis time is now similar for both ICP technolo- gies, at around two minutes per sam- ple, ICP-OES removes a dilution step compared to the preparation required for ICP-MS technology, saving on aver- age two hours per sample. Once pre- pared, samples are easily analyzed with ICP-OES, which removes laborious sam- ple preparation protocols and the po- tential interference that follows. With a much-reduced contamination risk, ICP-OES systems can be located in stan- dard laboratory space, without the need for cleanroom requirements. This broadens the usability and accessibili- ty of this technology, allowing a great- er number of laboratories to install the technology and strengthen their analyt- ical capabilities. In a recent study, a team of tech- nicians demonstrated the application of advanced ICP-OES technology in axi- al viewing mode for a range of electron- ic waste products. The study showed an excellent large linear dynamic range for REE (1 to 10,000 μg/L) and basic met- als (1 to 100,000 μg/L) on disassembled mobile phone components (see Fig. 2). Sensitivity in the low parts per bil- lion range was achieved for all target- ed analytes in the axial viewing mode and excellent system robustness was demonstrated. No significant results bias was seen in over two consecutive Fig. 1 — Analyte wavelengths, coefficient of determination R 2 (over a calibration range of 1–10,000 µg/L), instrumental detection limits (IDL, calculated by Qtegra ISDS Software), and method detection limits (MDL) for the rare earth elements and Th for the axial mode of the iCAP PRO XP Duo instrument.