A Hydrogen Peroxide Biosensor Based on Peroxidase Activity of Hemoglobin in Polymeric Film

2007 ◽  
Vol 7 (11) ◽  
pp. 4005-4008 ◽  
Author(s):  
A. K. M. Kafi ◽  
Dong-Yun Lee ◽  
Sang-Hyun Park ◽  
Young-Soo Kwon
Keyword(s):  
Hydrogen Peroxide ◽  
Phosphate Buffer Solution ◽  
Amperometric Detection ◽  
Buffer Solution ◽  
Long Term Stability ◽  
Sensor Performance ◽  
Redox Peak ◽  
Relative Standard ◽  
Optimized Conditions

A Hydrogen peroxide (H2O2) biosensor, based on hemoglobin (Hb) and ortho-phenylenediamine (o-PD) gold electrode, was fabricated. Hb was immobilized onto the electrode surface by electrochemical polymerize method with o-PD. The designed biosensor showed a well defined redox peak which was attributed to the direct electrochemical response of Hb. The immobilized Hb exhibited an excellent electrocatalytical response to the reduction of hydrogen peroxide, enabling the sensitivity determination of H2O2. Factors and performances such as pH, potential, influencing the designed biosensor, were studied carefully. The amperometric detection of H2O2 was carried out at −300 mV in phosphate buffer solution (PBS) (0.1 M) with pH 6.0. This biosensor showed a fast amperometric response (less then 5 s) to H2O2. The levels of the (Relative standard deviation) RSDs (<3 5%) for the entire analyses reflected a highly reproducible sensor performance. Using the optimized conditions, the detection limit of the biosensor was 1 × 10−7 M and linear range was from 5 × 10−6 to 1.25 × 10−4 M. In addition, this sensor showed long term stability and good sensitivity.

Microwave-assisted synthesis of NaA nanozeolite from slag and performance of Ag-doped nanozeolite as an efficient material for determination of hydrogen peroxide

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 52058-52066 ◽  
Author(s):  
Seyed Naser Azizi ◽  
Shahram Ghasemi ◽  
Mehrnaz Mikhchian
Keyword(s):  
Hydrogen Peroxide ◽  
Phosphate Buffer Solution ◽  
Modified Carbon Paste Electrode ◽  
Microwave Assisted Synthesis ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Microwave Assisted ◽  
And Performance ◽  
Paste Electrode

A new amperometric sensor is prepared based on a Ag doped NaA nanozeolite modified carbon paste electrode (Ag/ACPE) in order to detect hydrogen peroxide (H2O2) in phosphate buffer solution (PBS, pH 7.0).

Cloud Point Extraction and Spectrophotometry Determination of Lead in Environment Water Using 5-Br-PADAP

2013 ◽  
Vol 830 ◽  
pp. 345-348
Author(s):  
Lin Gao ◽  
Sheng Jie Chen ◽  
Fang Chen ◽  
Wen Hong Zhou ◽  
Jun Long Yao
Keyword(s):  
Cloud Point ◽  
Cloud Point Extraction ◽  
Detection Method ◽  
Low Cost ◽  
Calibration Graph ◽  
Buffer Solution ◽  
Relative Standard ◽  
Triton X ◽  
Optimized Conditions

A simple, sensitive, green and low cost detection method based on the cloud point extraction (CPE) separation and spectrophotometry was proposed for the determination of lead. In pH=9.0 H3BO3 buffer solution, Pb(II) reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in the presence of Triton X-100 yielding a hydrophobic complex, which then is extracted into micro-volume surfactant-rich phase. The calibration graph was linear in the range of 20-400 µg/L (at 560 nm). Under the optimized conditions, the detection limits of 10.94 µg/L and the relative standard deviations(RSD) of 2.0% (n=5) for Lead(II) were found, respectively. The sensitivity and absorbance of this method are at least five times higher when compared with that of usual 5-Br-PADAP spectrophotometry without CPE, and the proposed method has been applied to the determination of Lead in environment water samples with satisfactory results.

scholarly journals Spectrophotometric and RP-HPLC Methods for Determining Cefotaxime Sodium in Pharmaceutical Preparations

2020 ◽  
Vol 32 (6) ◽  
pp. 1314-1320
Author(s):  
Lamya A. Sarsam ◽  
Salim A. Mohammed ◽  
Sahar A. Fathe
Keyword(s):  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Pharmaceutical Preparations ◽  
Molar Absorptivity ◽  
Hplc Method ◽  
Buffer Solution ◽  
Limit Of Quantification ◽  
Rp Hplc ◽  
Relative Standard

A rapid, simple and sensitive spectrophotometric and RP-HPLC methods have been developed for the quantitative determination of cefotaxime-Na in both pure and dosage forms. The spectrophotometric method was based on diazotization of cefotaxime-Na and then coupling with 8-hydroxyquinoline in an alkaline medium. The resulting azo dye exhibited maximum absorption at 551 nm with a molar absorptivity of 0.597 × 104 L mol-1 cm-1. Beer′s law was obeyed over the range 10-700 μg/25 mL (i.e. 0.4-28.0 ppm) with an excellent determination coefficient (R2 = 0.9993). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0194 and 0.3765 μg mL-1, respectively. The recoveries were obtained in the range 97.3-102.5% and the relative standard deviation (RSD) was better than ± 1.56. The HPLC method has been developed for the determination of cefotaxime-Na. The analysis were carried out on a C18 column and a mobile phase composed of acetonitrile and phosphate buffer solution (0.024M KH2PO4 and 0.01M H3PO4) at pH 3.5 in the ratio of 60:40 (v:v), with a flow rate of 1.0 mL min-1 and UV detection at 258 nm. The proposed method showed good linearity (in a range of concentration 1.0-200 μg mL-1. The recovery percent and a relative standard deviations were found in the range 96 to 104.8% and ± 0.017 to ± 0.031%, respectively. Both methods were applied successfully to the assay of cefotaxime-Na in commercial injection preparations.

scholarly journals A novel dopamine electrochemical sensor based on La3+/ZnO nanoflower modified graphite screen printed electrode

2019 ◽  
Vol 9 (3) ◽  
pp. 187-195 ◽  
Author(s):  
Somayeh Tajik ◽  
Hadi Beitollahi ◽  
Mohammad Reza Aflatoonian
Keyword(s):  
Modified Electrode ◽  
Phosphate Buffer Solution ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Screen Printed Electrode ◽  
Buffer Solution ◽  
Optimized Conditions ◽  
Screen Printed

Flower-like La3+/ZnO nanocomposite was facile synthesized. A simple and ultrasensitive sensor based on graphite screen printed electrode (SPE) modified by La3+/ZnO nanoflower was developed for the electrochemical determination of dopamine. The electrochemical behavior of dopamine was studied in 0.1 M phosphate buffer solution (PBS) using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Compared with the unmodified graphite screen printed electrode, the modified electrode facilitates the electron transfer of dopamine, since it notably increases the oxidation peak current of dopamine. Also, according to CV results the maximum oxidation of dopamine on La3+/ZnO/SPE occurs at 150 mV which is about 140 mV more negative compared with unmodified SPE. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range from 0.15 to 300.0 μM, with a detection limit of 0.08 μM (S/N = 3). The proposed sensor exhibited a high sensitivity, good stability and was successfully applied for dopamine determination in dopamine ampoule, with high recovery.

Determination of caffeine, catechins and gallic acid in black tea of different geographical origin

2021 ◽  
Vol 87 (9) ◽  
pp. 12-19
Author(s):  
K. S. Gushchaeva ◽  
T. G. Tsyupko ◽  
O. B. Voronova ◽  
L. S. Malyukova
Keyword(s):  
Gallic Acid ◽  
Antioxidant Properties ◽  
Phosphate Buffer Solution ◽  
Black Tea ◽  
Buffer Solution ◽  
Optimized Conditions ◽  
Positive Effect ◽  
Main Consumer

We present the results of studying and selectiing optimal conditions for the determination of caffeine, catechins and gallic acid in black tea by the method of micellar electrokinetic chromatography. The choice of analytes is determined by the fact that they form the main consumer qualities of tea and, due to their antioxidant properties, have a positive effect on human health. Optimization of the electrophoretic detemination of seven catechins, caffeine and gallic acid in black tea was carried out using the method of ex­ periment design. Optimized conditions — 25 mM phosphate buffer solution with pH 7.4, containing 30 mM SDS and 5% ethyl alcohol — provided a satisfactory resolution of all electrophoretogram peaks, the analysis time was 25 minutes, and the current in the system did not exceed 120 pA. After the assessment of the metrological characteristics of the proposed method the standard deviation of the determina­tion of analytes did not exceed  15%. The  samples of black tea from Ceylon, Chinese, Assamese, Indian, Kenyan and Krasnodar regions of growth were analyzed, and an array of data on the contents of the analytes under study was formed. Discriminant analysis was used to develop a model and obtain classifica­tion functions for six tea groups from different regions of the world. Proceeding from the obtained classifi­cation functions, a scatter diagram of canonical values was constructed, which showed that the samples of Krasnodar and Chinese tea were localized from all the studied groups. Indian, Assamese and Ceylon teas formed a single area with close to the Chinese tea group. The correctness of the model was checked and revealed the total predictive force about 92%.  It is shown that the content of catechins, gallic acid and caf­feine are suitable markers for the classification of black tea samples from different regions of origin.

scholarly journals Electrochemical detection of carbidopa using a ferrocene-modified carbon nanotube paste electrode

2009 ◽  
Vol 74 (12) ◽  
pp. 1443-1453 ◽  
Author(s):  
Halimeh Yaghoubian ◽  
Hassan Karimi-Maleh ◽  
Ali Khalilzadeh ◽  
Fatemeh Karimi
Keyword(s):  
Phosphate Buffer Solution ◽  
Modified Carbon Paste Electrode ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Long Term Stability ◽  
Good Surface ◽  
Carbon Nanotube Paste Electrode ◽  
Paste Electrode

A chemically modified carbon paste electrode (MCPE) containing ferrocene (FC) and carbon nanotubes (CNT) was constructed. The electrochemical behavior and stability of the MCPE were investigated by cyclic voltammetry. The electrocatalytic activity of the MCPE was investigated and it showed good characteristics for the oxidation of carbidopa (CD) in phosphate buffer solution (PBS). A linear concentration range of 5 to 600 ?M CD, with a detection limit of 3.6?0.17 ?M CD, was obtained. The diffusion coefficient of CD and the transfer coefficient (?) were also determined. The MCPE showed good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for the determination of CD in real samples, such as urine samples.

Non-enzymatic determination of purine nucleotides using a carbon dot modified glassy carbon electrode

2019 ◽  
Vol 11 (30) ◽  
pp. 3866-3873 ◽  
Author(s):  
R. Karthikeyan ◽  
D. James Nelson ◽  
S. Abraham John
Keyword(s):  
Glassy Carbon ◽  
Low Cost ◽  
Phosphate Buffer Solution ◽  
Purine Nucleotides ◽  
Buffer Solution ◽  
Solution Ph ◽  
Carbon Dot ◽  
Enzymatic Determination ◽  
Sensitive Determination

Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.

Selective electromembrane extraction and sensitive colorimetric detection of copper(II)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Wajid Ali Khan ◽  
Muhammad Balal Arain ◽  
Hashmat Bibi ◽  
Mustafa Tuzen ◽  
Nasrullah Shah ◽  
...  
Keyword(s):  
Applied Voltage ◽  
Colorimetric Detection ◽  
Environmental Water ◽  
Selective Extraction ◽  
Effective Parameters ◽  
Relative Standard ◽  
Electromembrane Extraction ◽  
Optimized Conditions ◽  
Donor Phase

AbstractIn this study, an extremely effective electromembrane extraction (EME) method was developed for the selective extraction of Cu(II) followed by Red-Green-Blue (RGB) detection. The effective parameters optimized for the extraction efficiency of EME include applied voltage, extraction time, supported liquid membrane (SLM) composition, pH of acceptor/donor phases, and stirring rate. Under optimized conditions, Cu(II) was extracted from a 3 mL aqueous donor phase to 8 µL of 100 mM HCl acceptor solution through 1-octanol SLM using an applied voltage of 50 V for 15 min. The proposed method provides a working range of 0.1–0.75 µg·mL−1 with 0.03 µg·mL−1 limit for detection. Finally, the developed technique was applied to different environmental water samples for monitoring environmental pollution. Obtained relative recoveries were within the range of 93–106%. The relative standard deviation (RSD) and enhancement factor (EF) were found to be ≤4.8% and 100 respectively. We hope that this method can be introduced for quantitative determination of Cu(II) as a fast, simple, portable, inexpensive, effective, and precise procedure.

Development and Validation of HPLC Determination of related Substances in A Novel Anticonvulsant agent Epimidin

2021 ◽  
pp. 3223-3231
Author(s):  
Hanna I. Severina ◽  
Svitlana M. Gubar ◽  
Ivan V. Bezruk ◽  
Anna S. Materiienko ◽  
Liudas Ivanauskas ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Phosphate Buffer Solution ◽  
Anticonvulsant Drug ◽  
Strong Acid ◽  
Gradient Elution ◽  
Stress Conditions ◽  
Drug Candidate ◽  
Buffer Solution ◽  
Related Substances

1-(4-methoxyphenyl)-5-[2-[4-(4-methoxyphenyl)piperazin-1-yl]-2-oxo-ethyl]pyrazolo[3,4-d]pyrimidin-4-one has been reported as a promising new anticonvulsant drug candidate with a code name “Epimidin”. A new HPLC method for the related substances determination of potential active pharmaceutical ingredient has been developed and validated. The method uses ACE C18 column (250x4.6mm, 5µm) and gradient elution. Mobile phase consisted of a mixture of methanol R (mobile phase A) and phosphate buffer solution with triethanolamine, adjusted to pH 7.0 (mobile phase B). During the analysis, the ratio of mobile phases was changing according to a gradient mode at a flow rate of 1ml/min. The DAD detection was set at 240nm. The method was validated according to the ICH guidelines and requirements of State Pharmacopoeia of Ukraine. Drug substance was thoroughly explored for stability assessments under various stress conditions such as high temperature, as well as the influence of strong acid and base and oxidizing agents. The obtained solutions were analyzed by HPLC and LC/MS. It has been shown that the substance Epimidin was not resistant to the action of peroxide, alkali and acid decomposition – the mentioned stress conditions lead to the formation of unidentified impurities.

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