Determination of Low Levels of Arsenic using Flame AAS and Agilent UltrAA Lamps

Importance of the Topic

Arsenic contamination in nickel ores poses processing challenges and economic penalties when levels exceed approximately 200 ppm. Rapid screening methods capable of quantifying both high-level base metals and low-level arsenic from a single digest streamline quality control and resource evaluation in extractive metallurgy.

Study Objectives and Overview

This application note demonstrates a flame atomic absorption spectroscopy (AAS) method enhanced by Agilent UltrAA boosted discharge hollow‐cathode lamps for simultaneous determination of major base metals (Fe, Ni, Co, Cu, Zn) and trace arsenic in nickel ore.

Methodology and Instrumentation

The sample preparation involved digestion of 1 g milled ore with a mixed acid mixture (HNO₃, HCl, HF, HClO₄), evaporation, and reconstitution in 10 % HCl to 100 mL. An Agilent SpectrAA 55B with UltrAA lamp control and an arsenic UltrAA lamp was used. A Sample Introduction Pump System (SIPS) delivered standards and digests. Flame conditions compared were air-acetylene and nitrous oxide-acetylene.

Key Results and Discussion

• Calibration across three arsenic resonance lines (189.0 nm, 193.7 nm, 197.2 nm) showed the lowest characteristic concentration (0.37 mg/L) at 189.0 nm with air-acetylene. Nitrous oxide-acetylene offered reduced matrix interferences and higher flame transparency in the UV region, with a characteristic concentration of 0.62 mg/L at 189.0 nm.
• Analysis of 26 nickel ore samples (10–2500 ppm As in ore) achieved detection limits of 0.05–0.14 mg/L in solution (5–14 ppm in ore) without altering the base‐metal extraction protocol.
• Quality control demonstrated recoveries between 91 % and 104 % for standards and duplicates, and reliable discrimination at sub-ppm levels in solution.

Benefits and Practical Applicability of the Method

This single-technique approach enables rapid, accurate screening of nickel ore for both bulk metals and trace arsenic. It avoids additional hydride or graphite furnace steps, simplifies workflow, and reduces analysis time and costs in mining and metallurgical QC laboratories.

Future Trends and Opportunities

• Integration of automated sample introduction and data processing for higher throughput in mining operations.
• Extension of boosted‐lamp flame AAS to other challenging trace contaminants in complex matrices.
• Development of miniaturized or field‐deployable flame AAS systems with enhanced lamp technologies.

Conclusion

Combining nitrous oxide-acetylene flame AAS with UltrAA boosted lamps on a SpectrAA platform delivers a robust, streamlined method for concurrent determination of high-level base metals and low-level arsenic in nickel ores, improving laboratory efficiency and analytical performance.

References

No external literature citations were provided in the source document.