Determination of toxic elements in milk powder using Shimadzu ICPMS 2030

Significance of the topic

Milk powder is a globally consumed product with high nutritional value but can accumulate toxic elements from environmental and processing sources. Ensuring compliance with regulatory limits safeguards public health and supports international trade.

Study objectives and overview

This study evaluates the suitability of the Shimadzu ICPMS 2030 for quantifying trace toxic elements (As, Cd, Hg, Pb, Sn, Cu, Zn) in a commercial milk powder sample. The aim is to develop a sensitive, accurate method meeting FSSAI specifications and international benchmarks.

Methodology

The procedure involved microwave digestion of 500 mg milk powder with suprapure HNO₃ and water, following a temperature program ramping to 180 °C. Calibration standards (10–250% of FSSAI MRLs) were prepared in 16% HNO₃, with Ce, Y, Ge, Sc as internal standards at 20 ppb. Mercury memory effects were mitigated by adding 100 ppb Au to all solutions. Method linearity, limits of detection (LOD) and quantification (LOQ) were assessed, and spike recoveries at 20% and 200% MRL levels validated precision and accuracy.

Instrumentation used

• Shimadzu ICPMS 2030 with He collision cell (6 mL/min) for interference removal
• Micromist glass concentric nebulizer and quartz Peltier-cooled spray chamber
• Quartz mini torch and standard sample introduction system
• Online internal standard addition kit for automated IS delivery

Main results and discussion

Calibration curves exhibited excellent linearity (r ≥ 0.99987) across target concentration ranges. LOQs ranged from 0.002 ppm (Pb) to 0.155 ppm (Sn). Only zinc was detected at 23 ppm, reflecting its nutritional fortification. Spike recoveries (70–120%) and RSDs (<10%) confirmed method repeatability. Continuous calibration verification and QC checks yielded recoveries within 85–115%, demonstrating robustness and minimal drift under a 10 L/min plasma gas flow.

Benefits and practical applications

• Rapid, high-throughput analysis with online IS addition
• Compliance with FSSAI and AOAC guidelines for toxic elements in dairy
• Enhanced sensitivity and selectivity for trace-level detection
• Applicability to quality control and regulatory monitoring in the dairy industry

Future trends and applications

Advancements may include integration of automated sample preparation, use of high-resolution ICPMS for ultra-trace analysis, and expanded application to other complex food matrices. Ongoing method optimization could address emerging contaminants and stricter international regulations.

Conclusion

The developed ICPMS-2030 method with microwave digestion and online internal standard addition provides accurate, sensitive, and robust determination of toxic elements in milk powder. It meets regulatory requirements and enables reliable quality assurance in dairy products.

References

• Food Safety and Standards (Contaminants, Toxins and Residues) Regulations, 2011
• Food Safety and Standards (Contaminants, Toxins and Residues) Third Amendment Regulations, 2016
• AOAC Official Method 2015.01, Heavy Metals in Food