The Direct Determination of Cadmium in Blood by Electrothermal Atomization with the Graphite Platform

Importance of the topic

The accurate quantification of cadmium in human blood at trace levels is crucial for biomonitoring and health risk assessment. Cadmium exposure is linked to renal and bone toxicity and monitoring low concentration levels in unexposed populations presents analytical challenges due to complex blood matrix interferences.

Goals and study overview

This study aims to develop a reliable electrothermal atomic absorption method for direct determination of cadmium in diluted blood samples. It focuses on enhancing sensitivity and precision at sub-ng mL-1 levels by using a graphite platform and programmable sample injection.

Methodology and instrumentation

• Instrumentation Agilent AA-1275BD atomic absorption spectrophotometer coupled with Agilent GTA-95 graphite furnace and programmable sample dispenser.
• Sample preparation Simple dilution of blood with 0.2% Triton X-100 and 50% v v nitric acid modifier in a 1 10 ratio.
• Background correction Deuterium arc lamp to compensate for protein and salt induced background absorption.
• Graphite platform L Vov type platform installed inside pyrolytic graphite tube to minimize non spectral interferences.
• Programmable injection Preheating at 150 C allows deposition of 20 25 µL sample droplets without overflow.
• Ashing and atomization Ashing in air at optimized temperature reduces background followed by argon flush before atomization.

Main results and discussion

Direct tube injection yielded low and unstable signals with high background. The platform approach improved signal stability but required controlled injection volume and temperature. Air ashing reduced background absorbance to 0.3 A for 20 µL diluted blood and argon flushing enhanced reproducibility. Calibration curves in acid matrix paralleled standard addition in blood, indicating negligible matrix effects. Certified reference materials from Behring and Karolinska yielded cadmium concentrations in agreement with certified values across a range of 0.5 to 30 ng mL-1.

Contributions and practical applications

• Enables detection of cadmium at 0.05 3 ng mL-1 in blood with simple dilution and minimal sample handling.
• Programmable dispenser and platform use reduce matrix induced errors and improve precision.
• Suitable for routine clinical and environmental biomonitoring laboratories.
• Approach is adaptable to other trace metals in biological samples.

Future trends and possibilities

• Extension to other trace elements and complex biological matrices using similar platform strategies.
• Advances in automation and integration with hyphenated techniques for higher throughput.
• Development of portable and miniaturized electrothermal systems for field biomonitoring.
• Combination with microfluidic sample introduction to further reduce sample volumes and analysis time.

Conclusion

The described electrothermal atomic absorption method employing a graphite platform and programmable sample injection achieves reliable cadmium determination at sub ng mL-1 levels in blood. The protocol offers high sensitivity, minimal matrix interference, and potential for application to other trace metals with straightforward sample preparation.

Reference

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2. F Claeys Thoreau At Spectrosc 1982 3 188
3. B V L Vov Spectrochim Acta 1977 32B 153
4. F Delles and D Johnson Technical Tip No 11 Agilent USA 1984