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Determination of cadmium in coal using solid sampling graphite furnace high-resolution continuum source atomic
Alessandra Furtado da Silva1, Daniel L G Borges, Fábio Grandis Lepri
1Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis-SC, Brazil. welz@qmc.ufsc.br
Analytical and Bioanalytical Chemistry
|June 21, 2005
Summary
A new method uses iridium as a permanent chemical modifier for cadmium determination in coal via high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). This approach enables accurate cadmium analysis in solid coal samples with improved detection limits.
Area of Science:
- Analytical Chemistry
- Environmental Science
- Materials Science
Background:
- Accurate determination of cadmium in coal is crucial for environmental monitoring and regulatory compliance.
- Conventional methods often suffer from spectral interferences and matrix effects, necessitating complex sample preparation.
- High-resolution continuum source atomic absorption spectrometry (HR-CS AAS) offers enhanced spectral resolution but requires robust strategies to manage complex coal matrices.
Purpose of the Study:
- To develop and validate a novel method for the direct solid sampling determination of cadmium in coal.
- To utilize iridium as a permanent chemical modifier in conjunction with HR-CS AAS to improve analytical performance.
- To establish a reliable calibration strategy using aqueous standards for cadmium quantification in coal.
Main Methods:
- Development of a direct solid sampling technique for coal analysis using HR-CS AAS.
- Application of iridium (400 µg) as a permanent chemical modifier thermally deposited on a pyrolytic graphite platform.
- Optimization of pyrolysis (700 °C) and atomization (1500 °C) temperatures to minimize background absorption and matrix interferences.
- Calibration against aqueous standards for cadmium quantification.
Main Results:
- Successful interference-free determination of cadmium in seven certified coal reference materials and two real coal samples.
- Achieved good agreement with certified values at the 95% confidence level.
- Obtained a characteristic mass of 0.4 pg and a detection limit of 2 ng g⁻¹ for cadmium in coal (1.0 mg sample mass).
- Demonstrated typical precision (RSD) of <10% for coal samples within the 0.6-1.2 mg mass range.
Conclusions:
- The developed HR-CS AAS method with iridium permanent chemical modification provides a sensitive and accurate approach for cadmium determination in solid coal samples.
- Direct solid sampling eliminates the need for extensive sample digestion, simplifying the analytical workflow.
- The method effectively mitigates spectral interferences and background absorption common in coal matrices, enabling reliable quantification.