Advanced Approach towards Electrochemical Oxidation and Determination of Aripiprazole Using Gold and Boron-Doped Diamond Electrodes

Part I: Development of a solid phase extraction coupled with high performance liquid chromatography method for the determination of aripiprazole and dehydroaripiprazole in biological fluid Aripiprazole is the first drug with dopamine partial agonist effect for schizophrenia. Dehydroaripiprazole is its major metabolite. The determination and validation of aripiprazole and dehydroaripiprazole in human serum and urine were performed by a combination of solid phase extraction (SPE) and high performance liquid chromatography (HPLC) in this study. The method includes the following steps: 1) pre-treatment of acid-base solutions for deproteination, 2) application of SPE using an Oasis HLB cartridge for cleaning-up and concentration of the samples, 3) HPLC analysis. The recovery of sample pretreatment step was relatively high with recovery rate of 88.20 - 99.83 %. The optimized HPLC conditions were using a C18 X Terra® column, with an isocratic elution consisted of dipotassium phosphate buffer, pH 8.35, and acetonitrile (40 : 60 v/v) at a flow rate of 1.0 mL/min. The concentration of aripiprazole and dehydroaripiprazole could be determined within 5 minutes. The relative standard deviation (RSD) of the peak area for method repeatability (n = 4) and intermediate precision (inter-day, n = 3) were lower than 0.11 % and 5.16 %, respectively. The calibration curves revealed the method that was linear with concentration range between 50 - 1000 ppb for aripiprazole and 50 - 800 ppb for dehydroaripiprazole. Finally, the validated method was successfully applied to analyze serum and urine samples collected from patients receiving the aripiprazole treatment. The developed method can be used to quantitative determination of aripiprazole and dehydroaripiprazole concentration in patients’ serum and urine for therapeutic monitoring and clinical research. Part II: Fingerprint analysis of rhubarb by capillary electrophoresis and ultra-high pressure liquid chromatography This study used capillary electrophoresis (CE) and ultra performance liquid chromatographic (UPLC) method for chromatographic fingerprint analysis of rhubarb. With the application of chemometric approach, chromatographic fingerprint could be used for species differentiation. Ten common constituents in rhubarb, including aloe-emodine, (+)catechin, chrysophanol, emodine, (-)epicatechin gallate, gallic acid, physcion, rhein, sennoside A and sennoside B, were selected for analytical method development. The optimum micellar electrokinetic chromatography (MEKC) conditions were as followed: 30 mM sodium tetraborate / sodium dihydrogen phosphate monohydrate, 30 mM sodium deoxycholate (SDC), pH 8.6 with 26 % acetonitrile (v/v) as background electrolyte. The optimum condition of UPLC method used a Waters Acquity UPLC BEH C18 column for the separation. The mobile phase was composed of 0.05 % phosphate solution (solution A) and acetonitrile (solution B). The gradient profile was ( solution A: solution B): 0 min, 90 : 10; 25 min, 79 : 21; 35 min, 67 : 33; 40 min, 35 : 65; 45, min 35 : 65. The detector wavelength was set at 254 nm for both methods, and the total analytical time was 21 min for CE and 45 min for UPLC. Sixteen samples of Rheum officinale and Rheum tanguticum collected from various sources were analyzed by optimum analytical conditions. Chromatographic fingerprints of CE were subjected to peak alignment and baseline correction for further similarity test. On the other side, analytical results of UPLC show high precision with flat baseline. Chromatographic fingerprints of UPLC were directly used for Principal component analysis (PCA) and similarity test. PCA shows the chromatographic fingerprints of the two species could be successfully classified. The sample showing the least correlation with the representative chromatographic fingerprint was studied for its DNA sequences. DNA analysis demonstrated the sample to be a hybrid rhizome. The developed CE and UPLC chromatographic fingerprint methods could be applied for the quality control of rhubarb.

Voltammetric behavior of solifenacin succinate on gold, glassy carbon and boron-doped diamond electrodes: Stability testing and determination

Recent developments and advances in boron-doped diamond electrodes for electrochemical oxidation of organic pollutants

Boron-doped diamond (BDD) electrodes are eco-friendly and widely used in efficient water remediation through electrochemical advanced oxidation processes (EAOPs). These anodes can completely mineralize a wide range of pollutants, only requiring electrical energy. Over the last 2 decades, numerous commercially available BDD electrodes have emerged, but little is known about their electrooxidation performance, particularly if compared to laboratory-produced anodes by different research groups. In this critical review, a comparison between in-house-made and commercially available BDD electrodes based on a systematic literature review (SLR) is carried out. SLR was quite useful in locating and selecting the scientific publications relevant to the topic, enabling information gathering on dissemination, growth, and trends in the application of BDD electrodes in the degradation of water pollutants. More specifically, data concerning the origin of the employed BDD electrodes, and their physicochemical properties were extracted from a thorough selection of articles. Moreover, a detailed analysis of the main parameters affecting the BDD electrodes’ performance is provided and includes selection and pre-treatment of the substrate material, chemical vapor deposition (CVD) method, deposition parameters, characterization methods, and operational conditions. This discussion was carried out fully based on the numerous performance indicators found in the literature. Those clearly revealed that there are only a few analogous points across works, demonstrating the challenge of establishing an accurate comparison methodology. In this context, we propose a figure-of-merit equation which aims at normalizing BDD degradation results for a specific contaminant, even if working under different experimental conditions. Two case studies based on the degradation of solutions spiked with phenol and landfill leachate treatment with commercial or in-house-made BDD electrodes are also presented. Although it was not possible to conclude which electrode would be the best choice, we propose a set of guidelines detailing a consistent experimental procedure for comparison purposes in the future.

Electroanalytical sensing of indigo carmine dye in water samples using a cathodically pretreated boron-doped diamond electrode

Boron-doped diamond (BDD) electrode is an excellent candidate for anodic electrochemical oxidation of wastewater. However, higher concentrations of ClO3 − and ClO4 − of biotoxicity was found during chloride electrolysis using BDD electrodes compared to other electrode materials. In this study, BDD electrodes with five different boron doping concentrations were fabricated on silicon substrates using hot-filament chemical vapor deposition (HFCVD) method. The physical and electrochemical characterisation were conducted, which confirmed that with the decrease of boron concentration, the crystal size of the diamond decreased, oxygen evolution potential decreased, charge transfer resistance decreased while the electro-active surface area (EASA) increased. The electrochemical oxidation experiments of NaCl solution were carried out with these five BDD electrodes and time-dependent traces of product concentrations, current efficiencies and energy consumptions were compared and discussed. When the boron concentration increased, the minimum energy required to produce unit active chlorine (AC) decreased initially then increased, the same tendency was found in the yields of ClO3 − and ClO4 −. The lightly doped BDD (1.23 × 1020 cm−3) showed low energy consumption and high yield of AC, and low yields of ClO3 − and ClO4 −. Electrolysis of chlorine-containing organic wastewater was studied which further demonstrated the good performance of lightly doped BDD electrode.

This paper presents the application of a boron-doped diamond (BDD) electrode in the electrochemical oxidation of stable organic compounds. The BDD electrode exhibits a high anodic potential, generating high oxidation state radicals that facilitate the oxidation of tough organic compounds. In this study, the electrochemical oxidation approach is tested in the cleaning of residual organics left on a liquid crystal display (LCD) device. Results indicate that residual organic compounds adhered on an LCD device are decomposed completely in the experiment. It has been shown that the electrolyte temperature and concentration strongly affect the oxidation of tough residual organics such as phenylcyclohexane. Optimal cleaning performance is obtained at an electrolyte concentration of and a temperature between 50 and . The stability test of a BDD electrode measured by means of X-ray diffraction indicates that the BDD electrode remains unchanged after of operation. Moreover, the electrochemical oxidation technique has dramatically minimized the use of the ozone depleting substance commonly used as the organic solvent in the LCD manufacturing process.

Structured and graphitized boron doped diamond electrodes: Impact on electrochemical detection of Cd2+ and Pb2+ ions

Ultrasound enhanced electrochemical oxidation of phenol and phthalic acid on boron-doped diamond electrode

Highly efficient and energy-saving sectional treatment of landfill leachate with a synergistic system of biochemical treatment and electrochemical oxidation on a boron-doped diamond electrode

Electrochemical oxidation of organics in sulfate solutions on boron-doped diamond electrode: Multiple pathways for sulfate radical generation

Simple and highly sensitive assay of axitinib in dosage form and biological samples and its electrochemical behavior on the boron-doped diamond and glassy carbon electrodes

Pesticide wastewater is difficult to treat, and it is necessary to develop a new anode material electrochemical oxidation to efficiently degrade pesticide wastewater. DIL-PbO2-Ti/BDD electrodes with better electrocatalytic oxidation performance were obtained by using dicationic ionic liquid (DIL) for assisted electrodeposition of PbO2 modified boron-doped diamond (BDD) electrodes. At a current density of 100 mA cm-2 and a temperature of 25 °C, the DIL-PbO2-Ti/BDD electrode was used as anode and titanium plate as cathode. The electrochemical window and oxygen evolution potential (OEP) of the DIL-PbO2-Ti/BDD electrode obtained by CV testing at a scan rate of 50 mV s-1 in 1 M H2SO4 were 4.12 and 3.29 V, respectively. Under the conditions of current density of 100 mA cm-2, 25 °C, pH 12, salt content of 8%, chemical oxygen demand (COD) of 24,280.98 mg L-1, and total nitrogen (TN) content of 5268 mg L-1, after electrification for 12 h, the removal efficiency of COD and TN reached 64.88 and 67.77%, respectively, indicating that the DIL-PbO2-Ti/BDD electrode has excellent electrocatalytic performance. In order to further understand the mechanism of electrochemical degradation of pesticide wastewater, HPLC-MS was used to detect the intermediates in the degradation process, and the possible degradation pathways were proposed in turn.

Electroanalytical investigation and determination of pefloxacin in pharmaceuticals and serum at boron-doped diamond and glassy carbon electrodes

Theophylline is a drug with a narrow therapeutic range. Electrochemical sensors are a potentially effective method for detecting theophylline concentration to prevent toxicity. In this work, a simple modification of a boron-doped diamond electrode using nickel nanoparticles was successfully performed for a theophylline electrochemical sensor. The modified electrode was characterized using a scanning electron microscope and X-ray photoelectron spectroscopy. Square wave voltammetry and cyclic voltammetry methods were used to study the electrochemical behavior of theophylline. The modified nickel nanoparticles on the boron-doped diamond electrode exhibited an electrochemically active surface area of 0.0081 cm2, which is larger than the unmodified boron-doped diamond's area of 0.0011 cm2. This modified electrode demonstrated a low limit of detection of 2.79 µM within the linear concentration range from 30 to 100 µM. Moreover, the modified boron-doped diamond electrode also showed selective properties against D-glucose, ammonium sulfate, and urea. In the real sample analysis using artificial urine, the boron-doped diamond electrode with nickel nanoparticle modifications achieved a %recovery of 105.10%, with a good precision of less than 5%. The results of this work indicate that the developed method using nickel nanoparticles on a boron-doped diamond electrode is promising for the determination of theophylline.