Estimation of heavy metals in Infant food powder using Shimadzu inductively-coupled- plasma-mass spectrometry

Significance of the Topic

Exposure to toxic heavy metals such as arsenic, cadmium, lead and mercury even at trace levels can impair neurodevelopment and pose serious health risks, especially in infants and toddlers. Regulatory bodies like FSSAI set stringent maximum residual limits for these contaminants in infant food powder to ensure consumer safety. Accurate and sensitive analytical techniques are therefore essential to monitor and control these elements in dietary products.

Objectives and Study Overview

This study aimed to develop and validate a robust inductively coupled plasma–mass spectrometry (ICP-MS) method using the Shimadzu ICPMS-2030 system for quantifying seven elements (As, Cd, Cu, Hg, Pb, Sn, Zn) in commercially available infant food powder. Limits of quantification (LOQs) were established at 20% of FSSAI maximum residual limits and method performance was assessed via recovery, precision and linearity tests.

Methodology and Instrumentation

• Sample Preparation and Digestion
  0.5 g of powdered infant food was weighed into microwave vessels. Samples were pre-digested with ultrapure water, concentrated nitric acid (HNO₃) and hydrochloric acid (HCl), then subjected to a two-step microwave program (ramp to 120 °C for 5 min, then to 180 °C for 20 min). Final volumes were adjusted to 25 mL with ultrapure water.
• Internal Standards and Calibration
  Bismuth (Bi) and yttrium (Y) were employed as internal standards, with gold added to stabilize mercury. Seven-point calibration curves were prepared from certified reference solutions covering relevant concentration ranges (e.g., 0.1–2.5 µg/L for As, up to 2 500 µg/L for Zn).
• ICP-MS Analysis
  Analyses were carried out on the Shimadzu ICPMS-2030 equipped with an AS-10 autosampler and mini torch. Plasma RF power was set at 1.2 kW, with optimized gas flows (plasma gas 10 L/min, auxiliary gas 1.1 L/min, carrier gas 0.7 L/min) and helium collision cell at 6 mL/min. Electron-cooled cyclone chamber was maintained at 5 °C.

Main Results and Discussion

• All calibration curves exhibited excellent linearity (R² ≥ 0.997) across target ranges.
• Precision, expressed as %RSD, was < 6% for replicate preparations (n=4) and < 10% over the entire run sequence.
• Spike recoveries at LOQ and 10× LOQ levels ranged from 80% to 120%, demonstrating method accuracy.
• Toxic elements As, Cd, Hg, Pb and Sn were either below quantification limits or present at low levels (e.g., As at 0.012 ppm, Pb at 0.03 ppm). Copper and zinc were quantified at typical dietary concentrations (Cu ~3.67 ppm, Zn ~36.8 ppm).

Benefits and Practical Applications

The developed ICP-MS protocol offers high sensitivity, selectivity and throughput for routine monitoring of heavy metals in infant food. Its low detection limits and reliable recovery make it suitable for quality control laboratories in food safety, regulatory testing and industrial R&D.

Future Trends and Opportunities

Emerging directions include coupling ICP-MS with hyphenated separation techniques for speciation analysis, adopting greener sample preparation to reduce acid consumption, and implementing automated workflows to further increase sample throughput. Advances in collision/reaction cell technology may also enhance interferences removal and lower detection capabilities.

Conclusion

A sensitive and accurate ICP-MS method using Shimadzu ICPMS-2030 was successfully validated for quantifying key metals in infant food powder in compliance with FSSAI guidelines. The approach demonstrates excellent linearity, precision and recovery, confirming its suitability for regulatory and quality assurance testing.

References

• Food Safety and Standards (Contaminants, Toxins and Residues) Regulations, 2011
• AOAC Official Method 2015.01