Gipronikel Institute, Saint Petersburg, Russia:

V. A. Korotkov, Head of the Test & Analysis Centre, e-mail: KorotkovVA@nornik.ru
T. I. Velikaya, Principal Specialist at the Test & Analysis Centre
E. S. Poslavskaya, Lead Engineer at the Test & Analysis Centre

The existing methods standardized for to cobalt and nickel analysis, i.e. GOST 13047–2014, GOST 6012–2011 and GOST 8776–2010, don’t correspond to the current and future requirements to these metals in terms of impurities concentration. GOST 13047–2014 provides single-element analysis applications that establish a sample preparation for single element only, takes a lot of efforts and an extremely long time, consume a lot of chemical reagents and are associated with a significant harmful impact on the environment. Being a multielement technique, atomic emission spectrometry with DC-arc spectrum excitation is associated with a high consumption of chemical reagents and a significant environmental impact. It doesn’t allow determining the sulfur and other important impurities. All standard techniques are based on the obsolete principle to dissolve the samples in glass beakers on hot plates. The authors of this paper propose to standardize the methods of atomic emission spectrometry and mass spectrometry (MS) with inductively coupled plasma (ICP) to run cobalt and nickel analysis. 2.5 g samples of cobalt and nickel were proposed to decompose in a mixture of acids in closed polypropylene vessels heated in HotBlock systems at the temperature of 110 ^оC. This saved up to 5 cm³ of nitric acid and up to 5 cm³ of hydrochloric acid. The solutions of nickel and cobalt were analyzed for impurities on an iCAP 6500 Duo spectrometer at low plasma discharge power and using the base lines as an internal standard. This helped to improve the detection limits of impurities. To select optimal wavelengthes, full spectra of analyzed solutions were captured. Isotope 185Re was chose as internal standard and a collision and reaction cell was used to remove interfering polyatomic ions on an ICP-MS spectrometer iCAP Qc. Nickel and cobalt samples as well as CRMs were analyzed. The impurities detection limits with the current and future cobalt and nickel grades. The methods developed may create the basis for a new GOST standard applicable to cobalt and nickel analysis.

1. ASTM B880–14. Standard Specification for General Requirements for Chemical Check Analysis Limits for Nickel, Nickel Alloys and Cobalt Alloys. ASTM International, West Conshohocken, PA. 2019.
2. ASTM E2823–17. Standard Test Method for Analysis of Nickel Alloys by Inductively Coupled Plasma Mass Spectrometry (Performance-Based). ASTM International, West Conshohocken, PA. 2017.
3. TU 24.45.30-231-48200234–2017. Electrolytic cobalt. Specification.
4. GOST 849–2018. Primary nickel. Specifications. Introduced: 01.06.2018.
5. GOST 123–2008. Cobalt. Specifications. Introduced: 2018.
6. GOST 6012–2011. Nickel. Methods of chemical-atomic-emission spectral analysis. Introduced: 01.01.2013.
7. GOST 8776–2010. Cobalt. Methods of chemical-atomic-emission spectral analysis. Introduced: 01.04.2011.
8. GOST 13047–2014. Nickel. Cobalt. 2015.
9. Xi-du Nie, Yi-zeng Liang, Hua-lin Xie. Determination of trace elements in high purity nickel by high resolution inductively coupled plasma mass spectrometry. Journal of Central South University. 2012. Vol. 19. pp. 2416–2420.
10. Alekseev A. V., Yakimovich P. V., Kvachenok I. K. Determination of trace elements in nickel by ICP-MS. Trudy VIAM. 2020. No. 2.
11. Liang Fu, Shuyun Shi, Xiaoqing Chen, Hualin Xie. Analysis of impurity elements in high purity cobalt by inductively coupled plasma mass spectrometry. Microchemical Journal. 2018. Vol. 139. pp. 236–241.
12. Karimova T. A., Bukhbinder G. L., Kachin S. V. Application of inductively coupled plasma atomic emission spectrometry with concentration calibration for a silicate analysis of carbonaceous rocks. Zavodskaya laboratoriya. Diagnostika materialov. 2020. Vol. 86, No. 5. pp. 16–21.