Estimation of heavy metals at trace level in refined sugar using inductively-coupled- plasma-mass spectrometry

Importance of the Topic

Ensuring the safety of refined sugar is critical as trace heavy metals can pose serious health risks.
Regulatory agencies worldwide set strict limits on contaminants to protect consumers.

Study Objectives and Overview

This study evaluates the performance of the Shimadzu ICPMS-2030 in quantifying trace levels of arsenic, cadmium, chromium, copper, mercury, lead, and tin in white refined sugar.
The aim is to demonstrate sensitivity, accuracy, and precision of the method to meet Food Safety and Standards Authority of India (FSSAI) requirements.

Methodology and Instrumentation

Sample Preparation:

• 0.5 g sugar samples underwent microwave-assisted digestion with ultra-pure water, nitric acid, and hydrogen peroxide.
• Pre-spiking at LOQ, 2× LOQ, and 4× LOQ levels facilitated recovery checks.

Instrumentation:

• Shimadzu ICPMS-2030 with AS-10 autosampler.
• Octapole collision cell using helium gas to reduce polyatomic interferences.
• RF power: 1.2 kW; plasma gas flow: 10 L/min; auxiliary: 1.1 L/min; carrier: 0.7 L/min; collision gas flow: 6.0 mL/min.
• Internal standards: Scandium, Yttrium, and Bismuth at 10 ppb; gold (100 ppb) to mitigate mercury memory effects.
• Calibration: Sigma-Aldrich 1000 ppm CRMs diluted to 0.4–20 ppb (Cr: 0.1–5 ppb) in matrix-matched acid.

Main Results and Discussion

Limits of Detection (3σ) ranged from 0.0006 to 0.1156 ppb; LOQs (10σ) spanned 0.0018 to 0.3852 ppb.
No target elements were detected above LOQ in unspiked sugar samples (BLOQ).
Spike recoveries at LOQ, 2×, and 4× LOQ levels fell within 86–110%, confirming accuracy.
Precision was excellent with %RSD <5% across replicates; correlation coefficients ≥0.999 demonstrated strong linearity.

Benefits and Practical Applications

The validated ICP-MS method delivers rapid, reliable quantification of heavy metals in sugar and related food matrices.
It supports compliance with regulatory standards and quality assurance in food production.

Future Trends and Possibilities

Advances may include:

• Extending analyses to other food and environmental matrices.
• Integrating speciation studies to differentiate metal species.
• Enhanced collision cell and hyphenated techniques for improved throughput.
• Automation and cloud-based data processing for high-volume laboratories.

Conclusion

The Shimadzu ICPMS-2030, combined with optimized microwave digestion, provides a robust platform for trace-level heavy metal determination in sugar.
Its high sensitivity, precision, and streamlined workflow make it an ideal choice for routine food safety testing.

Reference

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