|Title||Quantitative determination of trace level (ng/g) contents of rhodium and palladium in copper-rich minerals using LA-ICP-MS|
|Author||Yang, Z; Jackson, S E; Cabri, L J; Wee, P; Longerich, H P; Pawlak, M|
|Source||Journal of Analytical Atomic Spectrometry vol. 35, issue 3, 2020 p. 534-547, https://doi.org/10.1039/c9ja00285e|
|Alt Series||Natural Resources Canada, Contribution Series 20200008|
|Publisher||Royal Society of Chemistry|
|Media||paper; on-line; digital|
|Subjects||economic geology; geochemistry; Science and Technology; Nature and Environment; mineral deposits; copper; sulphides; trace element analyses; palladium geochemistry; rhodium geochemistry; mass
spectrometer analysis; analytical methods; Methodology; platinum group elements|
|Illustrations||plots; 3-D diagrams; bar graphs|
|Program||Science laboratory network|
Geoscience Initiative (TGI-5) |
|Released||2020 01 20|
|Abstract||This study reports on the efficacy of measuring low ng/g contents of Rh and Pd in Cu-rich minerals by laser ablation single quadrupole (Agilent 7700x) and tandem MS (Agilent 8900x) ICP-MS, using helium
(He) collision gas and a mixture of ammonia (NH3)/He (10%/90%) reaction gas, respectively, to attenuate CuAr interferences on 103Rh and 105Pd. Results are compared with values obtained from digested separates of the same minerals (three synthetic
Cu-rich Fe sulphides, seven samples of chalcopyrite (CuFeS2) and two of bornite (Cu5FeS4) containing 24.17% to 63.31% Cu, less than 10 ng/g Rh and less than 250 ng/g Pd) analyzed using an Agilent 8800x ICP-MS/MS in NH3/He reaction mode. Using the
LA-ICP-MS/MS at an optimized NH3/He flow rate (0.3 mL/min), the CuAr contributions to 103Rh and 105Pd were less than 2.3 ng/g, which was a reduction of more than two orders of magnitude compared to those obtained using the single quadrupole LA-ICP-MS
at an optimized He collision gas flow (5 mL/min). The method limits of detection (MLOD) for 103Rh (1.7 ng/g) and 105Pd (7.0 ng/g) obtained using LA-ICP-MS/MS at the optimized NH3/He flow rate with a 110 micrometre ablation spot size were
approximately an order of magnitude lower than those (16 ng/g for Rh and 48 ng/g for Pd) obtained using single quadrupole LA-ICP-MS at the optimized He collision gas flow rate. The accuracy (difference from values for digested separates) and
precision (1RSD) of ng/g -level LA-ICP-MS/MS measurements of Rh and Pd (105Pd) in Cu-rich minerals were in the range of 0.5% to 19% and 19% to 31%, respectively. Moreover, this study shows that neither a linear CuAr interference correction strategy
nor the interference correction procedure of P. J. Sylvester, Mineral. Assoc. Can., Short Course Ser., 2001, vol. 29, p. 203 works effectively for accurate and precise LA-ICP-MS measurement of low ng/g contents of Rh and Pd in Cu-rich minerals. The
most accurate and precise measurement of Rh at less than 10 ng/g and Pd at ca. 100 ng/g in Cu-rich minerals is achieved using the Agilent 8900x LA-ICP-MS/MS in MS/MS acquisition mode at an optimized NH3/He reaction gas flow rate without a CuAr
interference correction. These results demonstrate the potential for LA-ICP-MS/MS to be widely used for the quantitative determination of trace level contents of the light PGE in transition metal sulphide minerals. |
|Summary||(Plain Language Summary, not published)|
This study investigates the effectiveness of a method for measuring very low amounts of the elements Rhodium (Rh) and Palladium (Pd) in copper-rich
minerals. Researchers used two types of mass spectrometry instruments and different gases to reduce interferences when analyzing these elements. They compared the results obtained from laser ablation inductively coupled plasma mass spectrometry
(LA-ICP-MS) using a single quadrupole instrument with those obtained using tandem mass spectrometry (MS/MS) and a double quadrupole instrument.
The key findings include that using the MS/MS instrument with optimized gas flow rates allowed for much
lower detection limits for Rh and Pd in the minerals compared to the single quadrupole instrument. The accuracy and precision of measurements were also improved with the MS/MS method, particularly for low levels of Rh and Pd in copper-rich minerals.
Interestingly, the study showed that traditional methods for correcting interferences from copper and argon were not very effective in this context.
The scientific impact lies in the development of a more accurate and sensitive method for
analyzing trace amounts of Rh and Pd in minerals, particularly in the presence of high levels of copper. This can have important applications in geology, mining, and materials science, as these elements are significant in various industrial processes
and mineral exploration. The study improves our ability to understand and quantify these elements in complex geological samples.