SampliQ OPT Solid Phase Extraction Sorbent in the Cleanup of Flavonoids in Ginkgo Biloba by HPLC-DAD

Significance of the topic

The determination of flavonoids such as quercetin, kaempferol and isorhamnetin in Ginkgo biloba products is critical for quality control and safety assessment in pharmaceutical and nutraceutical applications. These bioactive compounds exhibit antioxidant and cardioprotective effects, and their accurate quantification supports regulatory compliance and product standardization.

Objectives and Study Overview

This work aimed to develop and validate a solid-phase extraction (SPE) method using Agilent SampliQ Optimized Polymer Technology (OPT) cartridges for cleanup of flavonoids in Ginkgo biloba tablets, followed by rapid analysis with HPLC coupled to a diode array detector (DAD). The focus was on maximizing recovery, reducing matrix interferences and achieving low detection limits.

Methodology and Instrumentation

Sample preparation involved methanolic acid hydrolysis of ground tablet material, dilution, pH adjustment and filtration. The SPE protocol was optimized with conditioning (water, methanol), sample loading, two wash steps (aqueous methanol mixtures) and elution with pure methanol. HPLC separation was performed under isocratic conditions (40% 0.5% phosphoric acid, 60% methanol), using an Agilent ZORBAX Eclipse Plus C18 column (4.6×75 mm, 3.5 μm), 1.0 mL/min flow rate, 35 °C and detection at 370 nm.

Used Instrumentation

• Agilent 1200 Series HPLC system with diode array detector
• Agilent ZORBAX Eclipse Plus C18 column (4.6×75 mm, 3.5 μm)
• Agilent SampliQ OPT SPE cartridges (30 mg, p/n 5982-3013)
• Millipore Milli-Q water purification system
• Jenway 3510 pH meter

Main Results and Discussion

The SPE cleanup significantly reduced matrix interferences and enhanced analyte signals. Method performance was assessed in terms of recovery, precision and linearity:

• Recovery: quercetin 80–92%, kaempferol 83–94%, isorhamnetin 75–102% (n=6), all with RSD <5%.
• Linearity: r2 >0.999 up to 120 µg/mL (standards) and up to 400–500 µg/mL on SPE cartridges before overload.
• Limits of detection (LOD): 0.57 µg/mL (quercetin), 0.76 µg/mL (kaempferol), 0.88 µg/mL (isorhamnetin).
• Limits of quantification (LOQ): 1.91 µg/mL, 2.15 µg/mL and 2.55 µg/mL, respectively.
• Sample analysis: tablet extracts contained 26.42 µg/mL quercetin, 19.08 µg/mL kaempferol and 8.99 µg/mL isorhamnetin; leaf extracts yielded 12.35 µg/mL and 10.75 µg/mL for quercetin and kaempferol, respectively.

Benefits and Practical Applications

This SPE-HPLC-DAD approach offers rapid turnaround (9 min runtime), minimal solvent consumption, reliable cleanup and robust quantification. It is well suited for routine QC of herbal products, ensuring reproducible determination of key flavonoids in complex matrices.

Future Trends and Applications

Emerging directions include:

• Development of mixed-mode and molecularly imprinted polymer sorbents for enhanced selectivity.
• Integration with high-resolution mass spectrometry for lower detection limits and structural confirmation.
• Automation and miniaturization of SPE workflows to increase throughput and reduce solvent use.
• Adoption of greener solvents and sustainable sorbent materials.

Conclusion

The optimized SampliQ OPT SPE method coupled with HPLC-DAD provides an efficient, precise and sensitive protocol for quantifying quercetin, kaempferol and isorhamnetin in Ginkgo biloba products. It delivers high recoveries, low RSDs and meets stringent regulatory requirements for herbal supplement analysis.

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