Analysis of Herbal Medicines by ICPE-9000

Importance of the Topic

Herbal medicines are increasingly used worldwide as alternatives or complements to conventional therapies. Their complex matrices, containing minerals, botanical constituents and potential contaminants, demand rigorous quality control. Ensuring accurate metal quantification is essential to safeguard consumer health and comply with pharmacopeial standards.

Objectives and Study Overview

This study demonstrates the application of Shimadzu ICPE-9000 inductively coupled plasma atomic emission spectrometry (ICP-AES) for multi-element analysis of commercially available herbal products. Target analytes included toxic metals such as arsenic, cadmium, chromium, copper, mercury, lead and tin. The aim was to evaluate method performance, sensitivity, accuracy and throughput in a routine testing context.

Methodology

Samples of eight herbal medicines were subjected to microwave-assisted closed-vessel acid digestion using 7.5 mL HNO₃ and 0.5 mL HCl per 0.5 g dried sample. Digests were diluted to 25 mL with ultrapure water. Calibration employed multi-element standards and spike-recovery experiments. Quantitation followed external calibration curves, while semi-quantitative screening data were automatically retrieved from an integrated spectral database.

Used Instrumentation

• Instrument: Shimadzu ICPE-9000 ICP-AES
• Radio frequency power: 1.2 kW
• Plasma gas flow: 10 L/min; auxiliary gas: 0.6 L/min; carrier gas: 0.7 L/min
• Sample introduction: coaxial nebulizer with cyclone mist chamber
• Plasma torch: mini-torch, axial viewing
• Autosampler for high-throughput analyses

Main Results and Discussion

Semi-quantitative screening identified abundant elements (Ca, K, Mg) at weight percentages up to several percent. Quantitative data showed most toxic metals below or near detection limits (e.g., As < 0.2 µg/g, Pb < 0.1 µg/g). Recovery rates ranged from 95 to 101 %, demonstrating high accuracy. Interference from high Ca/Mg levels was effectively minimized by the high-temperature plasma of the mini-torch. Analytical cycle time was under 3 minutes per sample, enabling fast throughput.

Benefits and Practical Applications

Ultrafast measurement cycles, low running costs and minimal interference make this approach suited for quality control in pharmaceutical, nutraceutical and food industries. Automated sampling enhances laboratory efficiency and throughput.

Future Trends and Potential Applications

Developments may include coupling ICP-AES with hyphenated separation techniques, advanced interference correction algorithms and expanded monitoring of emerging contaminants. Integration into real-time quality management systems will further streamline compliance and risk assessment.

Conclusion

The Shimadzu ICPE-9000 offers a robust, sensitive and efficient solution for multi-element screening of herbal medicines. It meets pharmacopeial limits and provides reliable data to support safety evaluations and regulatory compliance.

References

1. Sixteenth Edition of Japanese Pharmacopoeia (Society of Japanese Pharmacopoeia).
2. WHO Guidelines for Assessing Quality of Herbal Medicines with Reference to Contaminants and Residues (2009, Japan Self-Medication Industry).
3. Green Trade Standards of Importing & Exporting Medicinal Plants & Preparations (2001, Ministry of Foreign Trade and Economic Cooperation, PRC).