The Quantitative Analysis of Curcuminoids in Food and Food Additives Using Rapid HPLC With Electrochemical, UV, or Fluorescence Detection

Significance of Topic

Turmeric and its active compounds, curcuminoids, are widely used both as culinary ingredients and in traditional medicine. The quantitative analysis of these bioactive compounds is essential for quality control, regulatory compliance, and research into their health benefits such as anti-inflammatory and antioxidant effects.

Objectives and Study Overview

This study aimed to develop and validate a rapid high-performance liquid chromatography (HPLC) method for quantifying three major curcuminoids—curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC)—in food matrices. The method was evaluated using electrochemical (EC), ultraviolet (UV), and fluorescence (FL) detection to determine sensitivity, selectivity, and suitability for stability studies.

Methodology and Instrumentation

• HPLC System: Thermo Scientific Dionex UltiMate 3000 with LPG-3400BM pump, WPS-3000 autosampler, and TCC-3000RS column compartment.
• Detection: ECD-3000RS electrochemical detector (6011RS ultra Coulometric cell, E1=E2=700 mV), FLD-3400RS fluorescence detector (excitation 426 nm, emission 539 nm), VWD-3100 UV detector (426 nm).
• Analytical Column: Acclaim RSLC PolarAdvantage II (2.1 × 50 mm, 3 µm).
• Mobile Phase: 25% 100 mM phosphate buffer (pH 3) and 75% methanol.
• Flow Rate and Injection: 0.4 mL/min, injection volume 2 µL.
• Data Processing: Chromeleon Chromatography Data System v6.8.
• Sample Preparation: Ultrasonic extraction of turmeric powder, curry powder, and curry sauce in methanol (1 mg/mL), filtration through 0.22 µm filter, dilution in mobile phase.

Main Results and Discussion

• Separation of curcumin, DMC, and BDMC was achieved in 3 minutes using the RSLC PA2 column without UHPLC hardware.
• Electrochemical detection provided the lowest limits of detection (LOD): 2 pg on-column for curcumin and DMC, 4 pg for BDMC; limit of quantitation (LOQ) was 10 pg with precision <10% RSD.
• Calibration was linear over 10–500 ng/mL with R² > 0.999 for all analytes.
• Compared with UV and FL detection, EC offered superior sensitivity and a uniform response, and uniquely detected a light- and pH-induced degradation product not visible by UV or FL.
• Quantitative analysis of real samples yielded curcuminoid contents (ng/mg): Japanese curry sauce (127 curcumin, 57.5 DMC, 374 BDMC), turmeric powder (17 255 curcumin, 7 797 DMC, 8 503 BDMC), and yellow curry powder (1 804 curcumin, 813 DMC, 847 BDMC).

Benefits and Practical Applications

The rapid 3 min HPLC method streamlines high-throughput quality control of turmeric and related food products. The high sensitivity and selectivity of EC detection enhance trace-level quantitation and enable monitoring of curcuminoid stability during processing and storage.

Future Trends and Potential Applications

• Integration with ultra-high performance systems for even faster separations.
• Expansion to other natural antioxidants and complex food matrices.
• Use of EC detection for comprehensive stability studies of phytochemicals under various stress conditions.
• Automation of sample preparation and on-line extraction techniques for industrial quality control.

Conclusion

A robust, 3 min HPLC method with electrochemical detection was established for rapid quantitation of major curcuminoids in food. Compared to UV and fluorescence methods, EC detection provides superior sensitivity, uniformity, and the ability to detect degradation products, making it a valuable tool for both research and quality assurance.

References

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