Ultra-Trace Analysis of Beryllium in Water and Industrial Hygiene Samples by ICP-MS

Significance of Ultra-Trace Beryllium Analysis

Exposure to airborne beryllium poses serious health risks, including acute and chronic pulmonary disease and potential carcinogenic effects. Regulatory agencies such as the U.S. EPA and NIOSH enforce stringent limits on Be concentrations in air and water, driving the need for analytical methods capable of detecting sub-ppt levels. Traditional ICP-OES methods require large air volumes and achieve detection limits near 0.2 ng/mL, whereas modern ICP-MS offers orders-of-magnitude improvements in sensitivity.

Objectives and Study Overview

The study aimed to demonstrate the capability of the Agilent 7500ce ICP-MS for ultra-trace quantification of beryllium directly in water and in acid digests of air filter samples. Key goals included:

• Establishing detection limits in the sub-ppt range under routine laboratory conditions
• Evaluating long-term precision and accuracy through extended analysis of certified reference water (NIST 1640)
• Assessing method performance on spiked cellulose membrane filters following a modified NIOSH 7301 digestion

Methodology and Sample Preparation

Water samples and filter digests were prepared in dilute nitric acid. NIST 1640 reference water was diluted from 1 to 10,000× and analyzed sequentially over 8.5 hours to test stability. Filter samples (47 mm cellulose ester, 0.8 µm pore) were spiked with 5 ppt Be, digested using a hot block and repeated additions of 1:3 HNO₃:HCl, then brought to volume with 1% HNO₃. Sequence blanks and calibration checks ensured quality control.

Used Instrumentation

The following ICP-MS configuration was applied:

• Instrument: Agilent 7500ce ICP-MS (no-gas collision cell mode)
• RF power: 1500 W; carrier gas: 0.8 L/min; sample flow: 400 µL/min
• Nebulizer: glass concentric; spray chamber cooled to 2 °C
• Extraction lenses: 2 V and –110 V; reaction mode off
• Analytes: ^9Be; internal standard: ^6Li; integration: 5 s per replicate, 3 replicates

Main Results and Discussion

Detection limit based on calibration and background was 52 ppq (0.000052 ng/mL), representing a 4,000× sensitivity gain over ICP-OES. Long-term reproducibility over 8.5 hours showed:

• 1,000× dilution (34.94 ppt theoretical): mean 34.13 ppt, 0.99% RSD, 97.7% recovery
• 10,000× dilution (3.49 ppt theoretical): mean 3.41 ppt, 2.51% RSD, 97.5% recovery

Filter spike tests gave 5.25 ppt mean (95.3% recovery) with 4.7% RSD; blank filters remained below 0.5 ppt. These results confirm the method’s robustness for ultra-trace Be in air matrices.

Benefits and Practical Applications

The high sensitivity and precision enable:

• Reduced air sampling volumes and shorter collection times
• Lower limits of quantification for regulatory compliance monitoring
• Reliable QA/QC in environmental and occupational hygiene studies

Future Trends and Opportunities

Advances may include automated on-line sample introduction, development of certified reference materials for filter matrices, enhanced collision/reaction cell chemistries to address interferences, and miniaturized or portable ICP-MS systems for field-based exposure assessment. Integrating speciation techniques could further improve understanding of Be bioavailability.

Conclusion

The Agilent 7500ce ICP-MS achieves sub-ppt detection of beryllium under routine conditions, overcoming space-charge and ionization challenges. Its demonstrated accuracy (>97% recovery) and precision (≤2.5% RSD) support reliable ultra-trace analyses in water and air filter samples, offering significant benefits for environmental and occupational health monitoring.

References

1. U.S. EPA beryllium toxicity values. http://www.epa.gov/ttn/atw/hlthef/berylliu.html
2. NIOSH Manual of Analytical Methods, Fourth Edition