Matrix CRM of green tea METRANAL® CRM AN-BM02

Significance of the Topic

Reference materials play a critical role in analytical chemistry by providing well-characterized standards for method validation, quality control and metrological traceability. A certified reference material (CRM) of green tea addresses the growing demand for reliable elemental analysis in nutritional, environmental and food safety laboratories.

Study Overview

This document presents the certification of METRANAL® CRM AN-BM02, a powdered green tea material produced in May 2022. The CRM is intended to support laboratories in transferring total element content values to similar matrices and ensuring SI-traceable measurements.

Methodology and Instrumentation

The CRM production followed ISO Guide 35 protocols for homogeneity and stability assessment. Key steps included:

• Particle size reduction to <200 μm
• Packaging in amber glass bottles (30 g each)
• Storage at 5–30 °C in dark, dry conditions

Recommended analytical techniques for total element determination are:

• Flame atomic absorption spectrometry (Flame AAS)
• Inductively coupled plasma optical emission spectrometry (ICP-OES)
• Inductively coupled plasma mass spectrometry (ICP-MS)
• High-temperature atomic absorption (AMA)

Metrological traceability was achieved using certified calibration standards directly traceable to SI units and by comparison with matrix-matched CRMs.

Main Results and Discussion

The certificate reports certified and indicative total concentrations for 24 elements (all values on a dry weight basis at 105 °C). Major findings include:

• Macroelements: Potassium ~16 000 mg/kg, Calcium ~5 100 mg/kg, Phosphorus ~2 250 mg/kg, Sulfur ~2 500 mg/kg, Magnesium ~1 930 mg/kg, Iron ~216 mg/kg, Manganese ~1 200 mg/kg
• Trace elements: Aluminium ~1 700 mg/kg, Zinc ~26 mg/kg, Copper ~13 mg/kg, Nickel ~4.8 mg/kg, Strontium ~22 mg/kg, etc.
• Potentially toxic elements: Arsenic ~0.156 mg/kg, Cadmium ~0.075 mg/kg, Lead ~1.54 mg/kg, Mercury ~0.014 mg/kg

Uncertainties (expanded, k=2) reflect dominant contributions from characterization. Homogeneity and short-term stability met ISO Guide 35 requirements.

Practical Benefits

Use of AN-BM02 CRM allows laboratories to:

• Validate analytical protocols and calibrations
• Demonstrate measurement traceability to SI units
• Compare results across methods and laboratories
• Enhance quality assurance in food and environmental analysis

Future Trends and Opportunities

Advancements in CRM development for botanical and food matrices may include:

• Speciation reference materials for key elements
• Nano- and sub-micro scale CRM formats
• Expansion to new crop varieties and processing states
• Lower uncertainty targets through improved characterization techniques

Conclusion

METRANAL® CRM AN-BM02 provides a well-characterized, stable and traceable resource for elemental analysis of green tea. Its use strengthens analytical reliability, supports method validation and underpins quality management systems in laboratories worldwide.

Reference

Certificate of METRANAL® CRM AN-BM02, Analytika, spol. s r.o., May 2022.