Analysis of milk powders based on Chinese standard method using the Agilent 5100 SVDV ICP-OES

Significance of the topic

The elemental composition of milk powder is a key indicator of both essential nutrient content and environmental contamination. Monitoring major nutrients such as sodium, potassium and calcium alongside trace toxic metals ensures compliance with food safety regulations and protects consumer health. The adoption of sensitive, robust analytical methods is critical for reliable quantitation across a wide concentration range.

Aims and study overview

This study evaluated China’s GB 5413.21—2010 standard method for determining eight elements in milk powder using the Agilent 5100 Synchronous Vertical Dual View (SVDV) ICP-OES with Dichroic Spectral Combiner (DSC). The objectives were to:

• Measure both major nutrient and trace element levels in a single analysis.
• Assess method detection limits against GB specifications.
• Verify accuracy and dynamic range using a certified milk powder standard.

Methodology and instrumentation

Sample preparation followed microwave digestion of 1 g of NIST SRM 8435 milk powder with concentrated HNO3 and H2O2. Digests were diluted to 25 mL in 20% v/v nitric acid. Multi-element calibration standards were prepared to cover concentrations from sub-ppb to percent levels for major and minor elements, eliminating manual sample dilutions.

Instrumentation

The Agilent 5100 SVDV ICP-OES with DSC technology enabled simultaneous axial and radial viewing in one reading. Key components and operating conditions included:

• Seaspray nebulizer and double-pass cyclonic spray chamber with a 1.8 mm torch.
• SPS 3 autosampler and online addition of yttrium internal standard.
• RF power of 1.3 kW, plasma flow 12 L/min, nebulizer flow 0.7 L/min.
• Read time 10 s, three replicates, uptake delay 20 s, stabilization time 15 s, rinse 30 s.

Results and discussion

Method detection limits for all elements were below the limits specified in GB 5413.21—2010. Recoveries from the NIST milk powder standard ranged from 92% to 107%, demonstrating method accuracy. The wide linear dynamic range permitted measurement of nutrient elements at the percent level radially and trace elements at the ppb level axially, all in a single run without additional sample dilutions. Additional elements (P, S, Sr, Mo) beyond the eight required by the Chinese standard were quantified successfully, highlighting the method’s versatility.

Benefits and practical applications

This approach offers:

• Fast, single-run analysis of major and trace elements.
• Reduced argon consumption and instrument cleaning.
• High accuracy and precision across a broad concentration range.
• Compliance with international food safety standards.

Future trends and applications

Advancements may include integration of more efficient sample introduction systems, expansion to additional trace analytes, and coupling with automated sample preparation workflows. Adaptation of dual-view ICP-OES technology to other complex food matrices and field-deployable platforms could further enhance rapid on-site screening and quality control.

Conclusion

The Agilent 5100 SVDV ICP-OES with DSC technology provides a robust, high-throughput solution for simultaneous determination of nutrient and toxic elements in milk powder. It meets Chinese GB 5413.21—2010 requirements with superior detection limits, accuracy and dynamic range, streamlining routine food safety testing.

References

1. P D Kluckner, D F Brown, R Sylvestre Analysis of milk by plasma emission spectrometry ICP Information Newsletter 1981 7 83
2. A J Ryan Direct analysis of milk powder on the Liberty Series II ICP-AES with the axially-viewed plasma ICP Instruments At Work 1997 ICP-21
3. A Tame, D Hoobin Direct analysis of milk powder by axially-viewed simultaneous ICP-OES Agilent application note 2010 ICPES-26
4. Agilent Technologies Synchronous Vertical Dual View for superior speed and performance Agilent publication 2014 5991-4853EN