Evaluation of Deuterium and Zeeman Background Correction with the Presence of Spectral Interferences Determinations of Arsenic in an Aluminium Matrix and Selenium in an Iron Matrix by GFAAS

Importance of the Topic

Graphite furnace atomic absorption spectrometry is essential for trace element analysis in complex matrices. Accurate background correction is crucial to avoid false positive or negative errors caused by molecular absorption or adjacent spectral lines. The comparison of deuterium and Zeeman background correction methods provides guidance for laboratories analyzing arsenic in aluminium and selenium in iron matrices.

Objectives and Study Overview

The study evaluates the performance of deuterium lamp and Zeeman effect background correction systems in correcting spectral interferences when determining arsenic at 193.7 nm in aluminium matrices and selenium at 196.0 nm in iron matrices. Matrix effects, spike recovery, detection limits, and method sensitivity are assessed using Agilent SpectrAA systems.

Methodology and Instrumentation

Instrumentation

• Agilent SpectrAA-880 with deuterium lamp background corrector
• Agilent SpectrAA-880Z with transverse Zeeman background corrector
• GTA-100 graphite furnace atomizer and PSD-100 programmable sample dispenser

Reagents and Sample Preparation

• Aluminium and iron stock solutions at 10 000 μg/mL diluted to 5–500 mg/L
• Arsenic and selenium intermediate standards at 1 μg/mL, calibration standards at 12, 36, and 60 μg/L
• In situ addition of nickel modifier (3 μL of 1000 μg/mL)

Thermal Program Summary

• Hot injection at 135 °C
• Dry step: 300–500 °C
• Ash step: 650–1400 °C depending on analyte
• Atomization: 2500–2600 °C
• Measurements recorded as both peak height and peak area

Main Results and Discussion

Arsenic in Aluminium Matrix

• Deuterium correction fails above 20 mg/L Al, causing positive bias and inflated recoveries
• Zeeman correction yields accurate As concentrations up to 300 mg/L Al; some interference appears above this level

Selenium in Iron Matrix

• Deuterium correction shows negative baseline shift and suppressed peak area; peak height remains usable up to 1000 mg/L Fe with careful furnace programming
• Zeeman correction effectively compensates for Fe spectral interference across all tested concentrations with consistent spike recoveries

Benefits and Practical Applications

The Zeeman background correction provides robust spectral interference removal for trace element analysis in challenging matrices. Deuterium correction is cost effective and suitable for less severe interferences. Proper selection of chemical modifiers and thermal programs ensures accurate results and low detection limits for environmental, industrial, and quality control laboratories.

Future Trends and Applications

Upcoming developments may include novel matrix modifiers for better peak separation, advanced magnet designs for improved Zeeman sensitivity, and automated method optimization. Integration of data-driven algorithms for real-time background correction and expansion to additional problematic matrix combinations will enhance analytical reliability and throughput.

Conclusion

Zeeman background correction outperforms deuterium lamp correction under high matrix loads for arsenic and selenium determinations. While deuterium correction remains useful at lower matrix concentrations, Zeeman offers superior accuracy and consistency. Laboratories should select the background correction approach based on matrix composition, interference severity, and instrument capabilities.

Reference

1. Christian GD. Analytical Chemistry. John Wiley & Sons; 1986.
2. Knowles M, Vanclay E. Performance Issues in Choosing a Zeeman Graphite Furnace Atomic Absorption Spectrometer. Chemistry in Australia. 1993;60:168.
3. Willard HH, Merritt LL, Dean JA, Settle FA. Instrumental Methods of Analysis. Wadsworth Publishing Company; 1981.
4. Frary B, Knowles M, Vanclay E. Unpublished work; 1993.