HPLC with Electrochemical Detection Systems for Quantitative Analysis of Functional Components in Foods
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-07-05 |
| Journal | BUNSEKI KAGAKU |
| Authors | A. Kotani, Yuji Miyaguchi, Naoto Miyashita, Fumiyo Kusu, Kiyoko Takamura |
| Institutions | Tokyo University of Pharmacy and Life Sciences |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Sensitivity HPLC-ECD using Boron-Doped Diamond (BDD) Electrodes
Section titled âTechnical Documentation & Analysis: High-Sensitivity HPLC-ECD using Boron-Doped Diamond (BDD) ElectrodesâExecutive Summary
Section titled âExecutive SummaryâThis research validates High-Performance Liquid Chromatography with Electrochemical Detection (HPLC-ECD) as a versatile and highly sensitive analytical platform for functional components in complex food matrices. The findings underscore the critical role of advanced electrode materials, specifically Boron-Doped Diamond (BDD), in expanding the application scope of ECD.
- BDD Superiority: The use of a Boron-Doped Diamond (BDD) working electrode was essential for the high-sensitivity quantification of cholesterol, a typically electro-inactive compound in aqueous media.
- Performance Gain: BDD electrodes achieved a 10-fold improvement in the Signal-to-Background (S/B) ratio compared to traditional Glassy Carbon (GC) electrodes for cholesterol analysis in acetonitrile media.
- Extended Window: BDD successfully extended the anodic potential window to +2.2 V vs. Ag/AgCl, enabling the direct electrochemical oxidation of cholesterol.
- High Sensitivity: The BDD method achieved a detection limit (S/N=3) of 8 nmol L-1 for cholesterol, demonstrating excellent precision (RSD 1.8%).
- Versatile Applications: HPLC-ECD systems were successfully applied to quantify catechins (using GC), isoflavones (using 2LC-ECD), and various acidic compounds (organic acids, fatty acids) via quinone mediator reduction.
- 6CCVD Relevance: 6CCVD specializes in the custom fabrication of the Heavy Boron-Doped Diamond (BDD) plates and wafers required to replicate and scale these high-performance electrochemical detection systems.
Technical Specifications
Section titled âTechnical SpecificationsâThe following data points highlight the performance achieved using electrochemical detection, focusing on the critical BDD application for cholesterol analysis.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Working Electrode (Cholesterol) | Boron-Doped Diamond (BDD) | N/A | Essential for extended anodic window |
| S/B Ratio Improvement (BDD vs GC) | ~10 | Times | Cholesterol analysis in acetonitrile |
| Applied Potential (BDD) | +2.2 | V vs. Ag/AgCl | Cholesterol oxidation |
| Detection Limit (BDD, S/N=3) | 8 | nmol L-1 | Cholesterol quantification |
| Linearity Range (BDD) | 20 nmol L-1 to 0.1 mmol L-1 | N/A | Cholesterol quantification |
| RSD (Cholesterol, Meat) | 1.8 | % (n=5) | Standard Reference Material |
| RSD (Catechins) | †4.0 | % (n=5) | Green/Oolong/Du Zhong Tea |
| Catechin Sensitivity Improvement | ~40,000 | Times | HPLC-ECD vs. HPLC-UV |
| Column Temperature | 40 | °C | Standard operating temperature |
| Flow Rate (BDD Cholesterol) | 30 | ”L min-1 | Micro-HPLC setup |
| BDD Mobile Phase | Acetonitrile + 10 mmol L-1 LiClO4 | N/A | Non-protic solvent required for BDD cholesterol detection |
Key Methodologies
Section titled âKey MethodologiesâThe research employed several advanced electrochemical and chromatographic techniques to achieve high selectivity and sensitivity:
- Electrode Material Optimization: Selection of the working electrode based on analyte electroactivity. Glassy Carbon (GC) was used for easily oxidized polyphenols (catechins), while Boron-Doped Diamond (BDD) was utilized for compounds requiring a wider anodic potential window (cholesterol).
- BDD for Non-Aqueous Media: Cholesterol detection was performed using BDD in an acetonitrile-based mobile phase to enable oxidation at +2.2 V vs. Ag/AgCl, minimizing background current and maximizing the S/B ratio.
- Quinone Mediator Sensing: A novel voltammetric acid sensing method was developed for electro-inactive acidic compounds (organic acids, fatty acids). This method utilizes the electro-reduction of a quinone mediator (e.g., VK3, DBBQ) in the presence of the acidic analyte, allowing detection without complex derivatization.
- Column Switching (2LC-ECD): A two-column, two-detector system (2LC-ECD) was implemented to separate compounds with large differences in hydrophobicity (e.g., isoflavone glycosides and aglycones) under stable isocratic conditions at the detector, thereby preserving high sensitivity.
- Micro-HPLC Implementation: The use of small-diameter columns (1.0 mm i.d.) and low flow rates (as low as 25 ”L min-1) was employed to enhance detection sensitivity and reduce solvent consumption, particularly beneficial for high-cost quinone mediators.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful replication and advancement of this high-performance HPLC-ECD research rely directly on access to high-quality, customized diamond materials. 6CCVD is uniquely positioned to supply the necessary components, particularly the critical Boron-Doped Diamond (BDD) electrodes.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend the high-sensitivity cholesterol and extended-potential analysis demonstrated in this paper, researchers require:
- Heavy Boron-Doped Diamond (BDD) Wafers/Plates:
- Application: Essential for high-potential anodic detection (e.g., cholesterol at +2.2 V) and achieving low background current in both aqueous and non-aqueous (acetonitrile) media.
- 6CCVD Capability: We offer BDD plates with customizable doping levels to optimize conductivity and electrochemical window width for specific applications.
- Polycrystalline Diamond (PCD) Substrates:
- Application: While the paper used GC for some applications, PCD can serve as a robust, chemically inert, and highly stable substrate for large-area electrochemical arrays or flow cells, offering superior longevity compared to GC.
- 6CCVD Capability: PCD plates available up to 125mm in diameter.
Customization Potential
Section titled âCustomization PotentialâThe integration of BDD into specialized flow cells (like the Radial Flow Cell used in the study) requires precise dimensions and robust electrical contacts. 6CCVD provides end-to-end customization:
| Requirement from Research | 6CCVD Customization Service | Technical Specification |
|---|---|---|
| Electrode Dimensions | Custom laser cutting and shaping | Plates/wafers up to 125mm (PCD) or custom SCD/BDD geometries for flow cells. |
| Electrode Thickness | Precision thickness control | SCD/BDD thickness from 0.1 ”m up to 500 ”m. |
| Surface Finish | Ultra-low roughness polishing | Polishing to Ra < 1nm (SCD) or Ra < 5nm (PCD/BDD) for optimal flow dynamics and minimized adsorption. |
| Electrical Contact | Custom metalization layers | Internal capability for depositing Au, Pt, Pd, Ti, W, and Cu contacts, ensuring reliable connection to the potentiostat. |
| Substrate Support | Thick, robust substrates | Substrates available up to 10mm thickness for mechanical stability in high-pressure HPLC systems. |
Engineering Support
Section titled âEngineering SupportâThe successful implementation of BDD-HPLC-ECD, particularly in complex non-aqueous systems or when utilizing mediator chemistry (as shown for fatty acids), requires deep material and electrochemical expertise.
- Material Selection: 6CCVDâs in-house PhD team provides expert consultation on selecting the optimal BDD doping level and crystal orientation for similar High-Potential Electrochemical Detection projects.
- System Integration: We assist engineers in defining the precise dimensions and metalization schemes necessary for integrating BDD wafers into commercial or custom flow cell designs, ensuring maximum S/B performance.
- Global Supply Chain: We offer reliable global shipping (DDU default, DDP available) to ensure researchers worldwide receive their custom diamond materials quickly and securely.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In the present review, various high-performance liquid chromatography with electrochemical detection (HPLC-ECD) systems are proposed for the quantitative analysis of functional components in foods. Determinations of catehines in tea were performed by an HPLC-ECD system using a glassy carbon working electrode. The distribution analysis of rutin, catechin, epicatechin, and epicatechin gallatein in buckwheat seed was achieved by HPLC-ECD with high sensitivity. Column-switching HPLC-ECD, which consists of one pre-column, two separation columns, and two amperometric detectors, called 2LC-ECD, was developed for determining isoflavones in soymilk. The determination of cholesterol, which was difficult to detect electrochemically in aqueous media, was performed by an HPLC-ECD system using a boron-doped diamond (BDD) working electrode and acetonitrile media; the present method was applied to analyze meat samples, such as pork loin, ground beef, and shoulder of mutton. Moreover, voltammetric acid sensing based on the reduction of quinone is provided for determining electro-inactive acidic compounds, such as fatty acids. The HPLC-ECD systems by means of the present sensing method were applied to determine organic acids in wine and yogurt, short-chain fatty acids (SCFAs) in fermented foods, free fatty acids (FFAs) in plant oils, and polyunsaturated fatty acids (PUFAs) in fish oil. The HPLC-ECD system for determining organic acids was applied to monitor a changing in organic acid concentrations in grape and milk during fermentation with wine yeast and yogurt, respectively. In conclusion, HPLC-ECD systems are shown as a powerful analytical strategy for the quantitative analysis of functional components in foods using simple sample preparations.