Gallic acid (3,4,5 trihydroxybenzoic acid) is a secondary metabolite present in most plants. This metabolite is known to exhibit a range of bioactivities including antioxidant, antimicrobial, anti-inflammatory, and anticancer. There are various methods to analyze gallic acid including spectrometry, chromatography, and capillary electrophoresis, among others. They have been developed to identify and quantify this active ingredient in most biological matrices. The aim of this article is to review the available information on analytical methods for gallic acid, as well as presenting the advantages and limitations of each technique.

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Gallic Acid: Review of the Methods of Determination and Quantification

A novel and efficient glucose biosensor based on the chemiluminescence (CL) detection of enzymatically generated H2O2 was constructed by the effective immobilization of glucose oxidase (GOX) on the Fe3O4–chitosan (Fe3O4–CS) nanoparticles support. The covalent immobilization of enzyme was performed using glutheraldehyde (GA) as a cross-linking agent. (H2O2 was constructed by one covalent immobilization of glucose oxidase in glutaraldehyde-functionalized glass cell). In addition to catalyzes the luminol CL reaction, gold NPs offer excellent catalytic activity toward hydrogen peroxide generation as a result of enzymatic reaction between glucose oxidase and glucose. Based on response surface methodology (RSM), the optimal immobilization conditions for glucose oxidase were obtained as: enzyme to support ratio, 0.7; Immobilization pH, 6; cross-linking time, 75 min; and glutaraldehyde (GA) concentration, 0.2%. The characterization of Fe3O4, Fe3O4–chitosan and Au nanoparticles was analyzed by XRD, FT-IR and SEM. The linear range of this novel method is 1 × 10−4 to 8.5 × 10−7 mol L−1 (R2 = 0.9956). The detection limit is 4.3 × 10−7 mol L−1. The relative standard deviation (RSD)

A novel glucose sensor based on immobilization of glucose oxidase on the chitosan-coated Fe3O4 nanoparticles and the luminol–H2O2–gold nanoparticle chemiluminescence detection system

A new electrochemical sensor was developed based on polyethyleneimine-functionalized graphene oxide (PEI-rGO) modified glassy carbon electrode (PEI-rGO/GCE). The synthetic positive charged PEI-rGO had good electron transfer ability, large specific surface area, prominent biocompatibility, and excellent adsorption. Its morphology and microstructure was characterized by scanning electron microscopy. The new electrode was firstly used for the detection of gallic acid, which exhibits superior performance in comparison to the bare glassy carbon electrode and graphene oxide modified glassy carbon electrode. The experimental conditions such as pH, adsorption time, and scan rate were optimized for the determination of gallic acid. Under optimum conditions, the linear regression equation of gallic acid was i p  = 12.76 c  − 11.44 ( i p : μA, c : mg/L, R  = 0.9887) from 0.1 to 10 mg/L with a detection limit (S/N = 3) of 0.07 mg/L. The method has been successfully applied to the determination of gallic acid in samples of green tea and black tea.

Sensitive detection of gallic acid based on polyethyleneimine-functionalized graphene modified glassy carbon electrode

A sensitive electrochemical sensor for determination of gallic acid based on SiO2 nanoparticle modified carbon paste electrode.

A facile and ultrasensitive sensor based on gold microclusters (AuMCs) electrodeposited on sulfonate functionalized graphene (SF-GR) was fabricated, and applied for the simultaneous determination of gallic acid (GA) and uric acid (UA). Taking advantage of the unique plane structure of the functionalized graphene (GR), the AuMCs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. The results of scanning electron microscope (SEM) and energy spectrum analysis illustrated that AuMCs were deposited on the functionalized GR film. In comparison with the bare GCE, the pristine AuMCs and the pristine SF-GR modified electrode, AuMCs/SF-GR/GCE exhibited excellent electrochemical oxidation toward GA and UA. In addition, the two compounds were separated completely in 0.10 M citric acid-sodium citrate buffer (pH 4.0) by differential pulse voltammetry (DPV) under optimum conditions. The anodic current was linearly related with 0.05–8.0 μM GA and 0.2–50.0 μM UA, with the detection limit of 10.7 nM and 0.12 μM, respectively. Furthermore, AuMCs/SF-GR/GCE was successfully applied to the independent determination of GA in black tea and Cortex moutan as well as the simultaneous determination of GA and UA in urine samples.

A simple, ultrasensitive sensor for gallic acid and uric acid based on gold microclusters/sulfonate functionalized graphene modified glassy carbon electrode

A novel flow injection procedure has been developed for the determination of gallic acid based on the enhancement function for luminol-AgNO3-Ag NPs chemiluminescence (CL) system by gallic acid. The enhancement mechanism was proposed for the reinforcing effect of the gallic acid on the CL system. The UV-vis absorption spectrum and CL emission spectrum were applied to confirm the mechanism. The method is simple, rapid and sensitive with a detection limit of 5×10−10 g·mL−1 and a linear range of 8.0×10−10–1.0×10−7 g·mL−1. The relative standard deviation (RSD) is 1.3% for eleven measurements of 5×10−8 g·mL−1 gallic acid. The method has been successfully applied to the determination of gallic acid in Chinese proprietary medicine–Jianmin Yanhou tablets and synthesized samples.

Determination of Gallic Acid by Flow Injection Analysis Based on Luminol‐AgNO3‐Ag NPs Chemiluminescence System

The oxidation reaction between cerium(IV) and Tween 85 in sulfuric acid medium produced weak chemiluminescence (CL). In this paper, it was found that citrate could strongly enhance the CL of cerium(IV)-Tween 85-polyphenol system. Based on studies of ultraviolet-visible spectra and CL spectra, the CL enhancement mechanism had been proposed. It was surmised that the light emission was from an excited oxygen molecular pair O2((1)Δg)O2((1)∑g(-)). The maximum emission wavelength was about 478 nm. The effects of 17 amino acids and 29 organic compounds on cerium(IV)-Tween 85-citrate CL were investigated by a flow injection procedure. This study showed the present system had a wide application for the determination of these compounds.

Li Qian

Papers

Determination of Gallic Acid by Flow Injection Analysis Based on Luminol‐AgNO3‐Ag NPs Chemiluminescence System

Enhanced chemiluminescence of cerium(IV)-Tween 85 system and the analytical application.