scholarly journals Detection of NADH and ethanol at a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite film

2012 ◽  
Vol 10 (1) ◽  
pp. 224-231 ◽  
Author(s):  
Jolanta Kochana ◽  
Juliusz Adamski
Keyword(s):  
Nanocomposite Film ◽  
Graphite Electrode ◽  
Limit Of Detection ◽  
Sol Gel ◽  
The Matrix ◽  
Titania Sol ◽  
Electrocatalytic Determination ◽  
Meldola's Blue ◽  
Meldola’S Blue

AbstractFor electrocatalytic determination of NADH, a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite was proposed. The composition of the matrix film was optimised in terms of the content of carbon nanotubes and Nafion. Incorporation of a redox mediator, Meldola’s Blue, into the nanocomposite film enabled electrocatalytic determination of NADH at a low potential, −50 mV. For determination of ethanol, alcohol dehydrogenase (ADH) was immobilized into the matrix layer. Experimental conditions affecting the biosensor response were examined, including enzyme loading, temperature of measurement and pH of background electrolyte. Assessments of the analytical characteristics of the biosensor were performed with respect to sensitivity, limit of detection, operational stability, repeatability and reproducibility. The proposed biosensor showed electrocatalytic activity toward oxidation of ethanol with sensitivity of 2.24 µA L mmol−1, linear range from 0.05 to 1.1 mmol L−1, and limit of detection of 25 µmol L−1. The apparent Michaelis-Menten constant was 1.24 mmol L−1, indicating a high biological affinity of ADH/titania sol-gel/Meldola’s Blue/MWCNT/Nafion electrode for ethanol. The developed biosensor was tested in determinations of ethanol content in alcoholic beverages.

scholarly journals Meldola’s Blue — doped titania sol-gel sensor for NADH determination

2011 ◽  
Vol 9 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Juliusz Adamski ◽  
Jolanta Kochana
Keyword(s):  
Sol Gel ◽  
High Sensitivity ◽  
Enzymatic Oxidation ◽  
Experimental Conditions ◽  
Gel Technique ◽  
Titania Sol ◽  
Doped Titania ◽  
Meldola's Blue ◽  
Meldola’S Blue

AbstractTitania layers obtained by a sol-gel technique doped with redox mediator, Meldola’s Blue, were employed for construction of a new NADH senor. Optimization of preparation process as well as experimental conditions affecting the response of the sensor were examined. Under optimal conditions NADH could be determined in the wide linear range from 90 to 2300 µM with detection limit 12 µM and a high sensitivity 12.5 nA µM−1. The usefulness of developed sensor was preliminarily checked in determination of NADH forming during enzymatic oxidation of ethanol catalyzed by alcohol dehydrogenase (ADH).

scholarly journals Determination of 77 Multiclass Pesticides and Their Metabolitesin Capsicum and Tomato Using GC-MS/MS and LC-MS/MS

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1837
Author(s):  
Harischandra Naik Rathod ◽  
Bheemanna Mallappa ◽  
Pallavi Malenahalli Sidramappa ◽  
Chandra Sekhara Reddy Vennapusa ◽  
Pavankumar Kamin ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Graphitized Carbon Black ◽  
Limit Of Quantification ◽  
Gas And Liquid Chromatography ◽  
Relative Standard ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Primary Secondary Amine

A quick, sensitive, and reproducible analytical method for the determination of 77 multiclass pesticides and their metabolites in Capsicum and tomato by gas and liquid chromatography tandem mass spectrometry was standardized and validated. The limit of detection of 0.19 to 10.91 and limit of quantification of 0.63 to 36.34 µg·kg−1 for Capsicum and 0.10 to 9.55 µg·kg−1 (LOD) and 0.35 to 33.43 µg·kg−1 (LOQ) for tomato. The method involves extraction of sample with acetonitrile, purification by dispersive solid phase extraction using primary secondary amine and graphitized carbon black. The recoveries of all pesticides were in the range of 75 to 110% with a relative standard deviation of less than 20%. Similarly, the method precision was evaluated interms of repeatability (RSDr) and reproducibility (RSDwR) by spiking of mixed pesticides standards at 100 µg·kg−1 recorded anRSD of less than 20%. The matrix effect was acceptable and no significant variation was observed in both the matrices except for few pesticides. The estimated measurement uncertainty found acceptable for all the pesticides. This method found suitable for analysis of vegetable samples drawn from market and farm gates.

scholarly journals Voltammetric Determination of Amoxicillin Using a Reduced Graphite Oxide Nanosheet Electrode

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Thi Hai Yen Pham ◽  
Thi Trang Mai ◽  
Hoang Anh Nguyen ◽  
Thi Thu Hien Chu ◽  
Thi Thu Ha Vu ◽  
...  
Keyword(s):  
Graphite Oxide ◽  
Graphite Electrode ◽  
Limit Of Detection ◽  
Reduction Process ◽  
Stripping Voltammetry ◽  
Active Surface ◽  
Active Surface Area ◽  
Accumulation Time ◽  
Reduced Graphite Oxide

A reduced graphite oxide nanosheet electrode (RGOnS) was prepared as a sensor for amoxicillin (AMX) detection, an antibiotic commonly used in the livestock farm, by the square-wave adsorptive stripping voltammetry technique. Graphite oxide with nanosheet shape was produced from a graphite electrode by a chronoamperometry process at 5 V and then an electrochemical reduction process was carried out to form RGOnS with restored long-range conjugated networks and better conductivity. The electrodes were characterized by SEM, EDX, and FTIR spectroscopy. The RGOnS electrode prepared at an optimal reduction potential of −1 V for 120 s exhibits a larger electrochemical active surface area, and the obtained oxidation signal of AMX is approximately ten times higher than that of the pristine graphite electrode. The analytical conditions such as the pH of electrolyte and accumulation time were optimized. The calibration curve built under the optimal conditions provided a good linear relationship in the range of AMX concentration from 0.5–80 µM with the correlation coefficient of 0.9992. The limit of detection was calculated as 0.193 µM. Satisfactory results are obtained from the detection of the AMX in different samples using the prepared electrode.

scholarly journals Luminol Doped Silica-Polymer Sensor for Portable Organic Amino Nitrogen and Ammonium Determination in Water

Separations ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 149
Author(s):  
Sara Bocanegra-Rodríguez ◽  
Carmen Molins-Legua ◽  
Pilar Campíns-Falcó
Keyword(s):  
Limit Of Detection ◽  
Nitrogen Concentration ◽  
Amino Nitrogen ◽  
In Situ Monitoring ◽  
Luminescence Signal ◽  
The Matrix ◽  
Ammonium Determination ◽  
Portable Sensor

We propose a portable sensor, obtained by embedding luminol into the tetraethylorthosilicate/trietoxymethylsilane (TEOS/MTEOS) composite, for the quantitative determination of organic amino nitrogen and ammonium in water with the goal of achieving low levels of concentration. The method is based on the reaction between amino nitrogen compounds and hypochlorite to produce chloramino derivatives. Then, the remaining hypochlorite reacts with luminol sensor by producing a luminescence signal, which was measured by using a portable luminometer, being inversely proportional to nitrogen concentration. The liberation of the luminol from sensor is higher than 90% and the sensor is stable for at least a week at room temperature. This portable method was successfully validated and applied to the analysis of several real waters: fountain, river transition, lagoon, and seawater with recovery values between 92% and 112%, which indicated that the matrix effect was absent. The achieved limit of detection was around 10 µg·L−1, expressed as N. This sensor allows in situ monitoring owing to its simplicity, rapidity, and portability.

scholarly journals Development of the High Sensitivity and Selectivity Method for the Determination of Histamine in Fish and Fish Sauce from Vietnam by UPLC-MS/MS

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Quang Hieu Tran ◽  
Thanh Tan Nguyen ◽  
Kim Phuong Pham
Keyword(s):  
Limit Of Detection ◽  
High Sensitivity ◽  
Fish Sauce ◽  
Limit Of Quantification ◽  
Fish Samples ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Sensitivity And Selectivity ◽  
Liquid Chromatographic

A selective, sensitive, and rapid method by using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the determination of histamine in fish and fish sauce was developed. The optimal conditions of liquid chromatographic separation and mass spectroscopy of histamine have also been investigated. The linear ranges of the method were 20.0 ÷ 1000 ng/mL, and the corresponding correlation coefficient was 0.9993. Mean recoveries of the analyte at three spike levels (low, medium, and high) were within the range of 98.5% ÷ 102.5% (n = 7). The limit of detection (LOD) and limit of quantification (LOQ) values were 3.83 and 11.50 ng/mL for the fish sauce sample and 4.71 and 14.12 ng/mL for the fish sample, respectively. The influence of the matrix effect on the accuracy, repeatability, and recovery of the method was negligible. The recommended method was applied to determine the content of this substance in 21 fish sauce samples and 4 kinds of fish samples, which were collected from Ho Chi Minh City, Vietnam, in 2019.

scholarly journals Pipette Tip Solid-Phase Extraction Combined with Fluorescence Spectroscopy for Determination of Selenium in Green Tea Samples

2021 ◽  
Vol 913 (1) ◽  
pp. 012064
Author(s):  
S R Kamali ◽  
C H Tsai ◽  
C N Chen
Keyword(s):  
Solid Phase Extraction ◽  
Green Tea ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Standard Addition ◽  
Phase Extraction ◽  
Addition Method ◽  
The Matrix ◽  
Pipette Tip

Abstract In this study, the custom-built pipette-tip solid phase extraction (PT-SPE), was used for pre-concentrating the selenium (Se) in green tea samples. The PT-SPE was prepared using a pipette tip and C18 as the adsorbent that was placed between glass wool. This method afforded several advantages in terms of efficiency of extraction time (8 min), sample (2 mL), and solvent (1 mL) volumes with less wastage of solvent. Under optimal conditions of extraction, this method yielded good linearity (r2=0.998) for the Se calibration curve and good limit of detection (0.2 μg/L) and quantification (0.6 μg/L). The standard addition method was used to remove the matrix effect. The recovery percentages of tea samples spiked with different Se concentrations ranged from 97.7 to 106.0%, indicating that the proposed method would be suitable for the determination of Se in green tea samples.

scholarly journals Development and Application of a Novel QuEChERS Method for Monitoring of Tributyltin and Triphenyltin in Bottom Sediments of the Odra River Estuary, North Westernmost Part of Poland

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 591 ◽  
Author(s):  
Dawid Kucharski ◽  
Przemysław Drzewicz ◽  
Grzegorz Nałęcz-Jawecki ◽  
Kamila Mianowicz ◽  
Artur Skowronek ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
Matrix Effect ◽  
Limit Of Detection ◽  
River Estuary ◽  
Organotin Compounds ◽  
Two Samples ◽  
Odra River ◽  
The Matrix ◽  
Signal Response

A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction method combined with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) for determination of organotin compounds (OTC) has been newly developed. The novel analytical method was validated and the quality of the results was tested by the use of certificate reference material of freshwater sediment BCR 646. The method was applied in determination of OTC concentration in real samples of bottom sediments collected from the Polish part of Odra River Estuary. The samples came from locations with different anthropogenic impact. Additionally, the extraction recovery of OTC and matrix effect on MS signal response was investigated based on those real environmental samples. It was found that organic compounds and anthropogenic contaminations present in bottom sediments may affect extraction efficiency of the organotin compounds (OTC) and change the matrix effect on MS signal response. The highest concentrations of tributyltin were found in bottom sediments collected from locations in vicinity of the Szczecin harbor and shipyards. The presence of triphenyltin above limit of detection (5 ng TPhT/g of sediment) was observed only in two samples and its concentration was several times lower compared to concentration of tributyltin (from 58 ng/g to 5263 ng/g). In spite of the fact that, the application of TBT-based paints on hull of vessel entering EU ports has been banned by European Commission regulation No. 782/2003 since 2008, the OTC compounds are still present in bottom sediment and pose significant threat to the environment. This threat should be taken into account during dredging of waterways and other hydrotechnical works.

Sign in / Sign up

Export Citation Format

Share Document