scholarly journals A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 422
Author(s):  
Nazaruddin Nazaruddin ◽  
Nurul Afifah ◽  
Muhammad Bahi ◽  
Susilawati Susilawati ◽  
Nor Diyana Md. Sani ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ph Value ◽  
Ph Sensor ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Rigor Mortis ◽  
C Storage ◽  
Relative Standard ◽  
Vis Spectroscopy ◽  
Optical Ph Sensor

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4oC storage. The quantitative pH values were measured based on the UV-Vis spectroscopy absorbance. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor’s reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness. Overall, this reported optical pH sensor has a novelty as it could be used to monitor the rigor mortis phase of fish meat, which is useful in food industry.

scholarly journals A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 422
Author(s):  
Nazaruddin Nazaruddin ◽  
Nurul Afifah ◽  
Muhammad Bahi ◽  
Susilawati Susilawati ◽  
Nor Diyana Md. Sani ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Room Temperature ◽  
Ph Value ◽  
Ph Sensor ◽  
Phosphate Buffer Solution ◽  
Good Sensitivity ◽  
Buffer Solution ◽  
C Storage ◽  
Relative Standard ◽  
Optical Ph Sensor

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4oC storage. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor’s reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness.

scholarly journals Preparation and Characterization of a Pectin Membrane-Based Optical pH Sensor for Fish Freshness Monitoring

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 60 ◽  
Author(s):  
Uswatun Hasanah ◽  
Mita Setyowati ◽  
Rustam Efendi ◽  
Muslem Muslem ◽  
Nor Diyana Md Sani ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Response Time ◽  
Relative Standard Deviation ◽  
Ph Sensor ◽  
Sensor Response ◽  
Relative Standard ◽  
Optical Ph Sensor

In a simple and instant procedure for detecting fish freshness, a hydrogel and hydrophilic pectin matrix membrane was used successfully as an optical pH sensor by immobilizing the chromoionophore ETH 5294 (CI), which is very selective and sensitive for the membrane. The Pe/CI optical pH sensor exhibited excellent linearity between pH 5 and pH 9, with a sensor response time of 5 min and reproducibility of 1.49% relative standard deviation (RSD). The sensor showed response stability for 15 days and a response reduction of 8.6%. The sensor’s capability was demonstrated by the detection of fish freshness for 17 days at 4 °C.

scholarly journals Optical pH sensor based on polyelectrolyte complex (PEC) pectin-chitosan/methanol anthocyanin extract of Catharanthus roseus for a new optical urea biosensor development

2021 ◽  
Vol 21 (3) ◽  
pp. 135-141
Author(s):  
NURHAYATI NURHAYATI ◽  
EKA SAFITRI ◽  
KHAIRI SUHUD ◽  
NAZARUDDIN NAZARUDDIN ◽  
BINAWATI GINTING ◽  
...  
Keyword(s):  
Catharanthus Roseus ◽  
Phosphate Buffer ◽  
Polyelectrolyte Complex ◽  
Ph Sensor ◽  
Total Phenolic ◽  
Buffer Solution ◽  
Good Linearity ◽  
Relative Standard ◽  
Ph Range ◽  
Optical Ph Sensor

Construction of optical pH sensor as a new platform optical urea biosensor based on polyelectrolyte complex (PEC) pectin-chitosan membrane and total phenolic (anthocyanin) of Tapak Dara flower (Catharanthus roseus) has been successfully carried out. The anthocyanin was extracted by a maceration method for 72 hours using methanol, and a total extract yield was 21.56% or 1.803 mg/L. Flavonoid and phenol tests showed positive results indicated by the formation of red and black colours. The anthocyanins showed maximum absorption at 578 nm for phosphate buffer and 575 nm for tris HCl buffer solution. The sensor fabrication was performed using a mixture of pectin and chitosan solutions with a ratio of 3:7. The anthocyanin was mixed into the solution with various concentrations. The sensor has an optimum sensitivity at the anthocyanin concentration of 0.05 mg/L (phosphate buffer) in the pH range of 7.0-9.5 and 0.025 mg/L (Tris HCl buffer) with a narrower pH range of 6.0-7.5. This sensor produced higher sensitivity, a wider linear range, and good linearity when it was exposed in 0.03M PBS. Reproducibility test with a relative standard deviation percentage (% RSD) was 9.20. The sensor showed a stable response after 5 minutes exposed to PBS solution, and it can be used to measure pH within the 20th day. The optimized optical pH sensor has been successfully developed as a urea optical biosensor by immobilizing urease on its surface. The biosensor showed a linear response in a series of 10-1-10-10 M urea concentrations and has good linearity.

scholarly journals Optical pH Sensor Based on Immobilization Anthocyanin from Dioscorea alata L. onto Polyelectrolyte Complex Pectin–Chitosan Membrane for a Determination Method of Salivary pH

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1276
Author(s):  
Eka Safitri ◽  
Hani Humaira ◽  
Murniana Murniana ◽  
Nazaruddin Nazaruddin ◽  
Muhammad Iqhrammullah ◽  
...  
Keyword(s):  
Polyelectrolyte Complex ◽  
Ph Sensor ◽  
Dioscorea Alata ◽  
Anthocyanin Content ◽  
Buffer Solution ◽  
Citrate Buffer ◽  
Relative Standard ◽  
Significant Difference ◽  
Salivary Ph ◽  
Optical Ph Sensor

A simple optical pH sensor based on immobilization, Dioscorea alata L. anthocyanin methanol extract, onto a pectin–chitosan polyelectrolyte complex (pectin–chitosan PEC), has been successfully fabricated. The optical pH sensor was manufactured as a membrane made of pectin–chitosan PEC and the extracted anthocyanin. This sensor has the highest sensitivity of anthocyanin content at 0.025 mg/L in phosphate buffer and 0.0375 mg/L in citrate buffer. It also has good reproducibility with a relative standard deviation (%RSD) of 7.7%, and gives a stable response at time values greater than 5 min from exposure in a buffer solution, and the sensor can be utilized within five days from its synthesis. This optical pH sensor has been employed to determine saliva pH of people of different ages and showed no significant difference when compared to a potentiometric method.

Determination of Pb2+ in Wastewater by Lead(II)-dithizone-xylenol Orange Tenary Complex Spectrophotometry

2014 ◽  
Vol 1030-1032 ◽  
pp. 301-304 ◽  
Author(s):  
Jian Qi Sun
Keyword(s):  
Standard Deviation ◽  
Ph Value ◽  
Xylenol Orange ◽  
Direct Determination ◽  
Sodium Cyanide ◽  
Relative Standard ◽  
Efficient Recovery ◽  
Wastewater Samples ◽  
Orthogonal Tests

An novel Lead (II)-dithizone-xylenol orange tenary complex spectrophotometry was developed for the determination of Pb2+ in wastewater. For this purpose, the parameters of spectrophotometry such as the detection wavelength, pH value, the dosage of dithizone-xylenol orange and reaction time were studied and optimized through orthogonal tests. The method was linear in the ranges from 2.1×10-3 to 6.0 μg·mL-1 for Pb2+ with R2≥ 0.999. The procedure allowed efficient recovery of the investigated Pb2+ ranging between 95 % and 103 % with a relative standard deviation (RSD) ≤ 2.1 for actual wastewater samples spiked with 1.00, 2.00 and 3.00 μg·mL-1 of standard Pb2+, respectively. These results show the method can be applied to the direct determination of Pb2+ in wastewater, avoiding the use of toxic extrant (chloroform) and masking reagent (sodium cyanide) in the traditional methods and time-consuming procedures, moreover, the investigated method is simple, accurate, reliable, and inexpensive, which implies the potential of this technique for Pb2+ monitoring in wastewater samples.

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.

Electrochemistry and Electrocatalysis of Hemoglobin Based on Graphene Quantum Dots Modified Electrode

2020 ◽  
Vol 16 (3) ◽  
pp. 308-315
Author(s):  
Xiaoyan Li ◽  
Hui Xie ◽  
Guiling Luo ◽  
Yanyan Niu ◽  
Xiaobao Li ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Modified Electrode ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Catalytic Reduction ◽  
Graphene Quantum Dots ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Detection Range ◽  
Electrochemical Behaviors

Background: Graphene quantum dots (GQD) is a new member of carbon nanomaterial that has attracted increasing attention owing to its better chemical inertness, low cytotoxicity, large specific surface area, cheap cost, suitable conductivity and excellent biocompatibility. Methods: Electrochemical behaviors of this modified electrode were studied by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical investigations of Nafion/Hb/GQD/ CILE were carried out with electrochemical parameters calculated. Results: In the phosphate buffer solution with a pH value of 5.0, good linear relationships between the catalytic reduction current and the concentration of substrate were got for TCA (6.0~100.0 mmol·L-1), NaNO2 (2.0~12.0 mmol·L-1) and H2O2 (6.0~30.0 mmol·L-1). The proposed method was applied to NaNO2 concentration detection in soak water from picked vegetables with satisfactory results. Conclusion: This Nafion/Hb/GQD/CILE had a good bioelectrocatalytic activity to different substrates such as trichloroacetic acid, NaNO2 and H2O2 reduction with the advantages including wide detection range, low detection limit and good stability. Therefore, the application of GQD in electrochemical sensor was extended in this paper.

Encapsulation of Urease in Molybdenum Trioxide Sol-Gel

2004 ◽  
Vol 828 ◽  
Author(s):  
Prashant K. Jha ◽  
P. I. Gouma
Keyword(s):  
Gas Sensing ◽  
Molybdenum Trioxide ◽  
Ph Value ◽  
Sol Gel ◽  
Microstructural Analysis ◽  
Phosphate Buffer Solution ◽  
Gaseous Ammonia ◽  
Buffer Solution ◽  
Transmission Electron ◽  
The Matrix

ABSTRACTMolybdenum trioxide sol-gel matrices were tested for their ability to host biomaterials in their structures without adversely affecting the activity of the encapsulated biomolecules. The sol-gel composites were prepared at room temperature; the urease was added during the hydrolysis step to ensure proper encapsulation in the pore structure of the sol. Phosphate buffer solution was added during this stage to maintain the pH value of the sol in the bio-compatible range. The activity of incorporated urease was tested by exposing composite sol-gel material to standard urea test solutions and measuring the amount of gaseous ammonia (released by the reaction of urea with water in the presence of urease) using an ammonia electrode. The concentration of urea solutions ranged from 1mM to 10mM. An electronic olfactory system (EOS 835) was also employed to detect the presence of gaseous ammonia. Gas sensing tests were done to verify the sensitivity of the matrix to ammonia. Microstructural analysis was carried out by means of scanning and transmission electron microscopy. It was found that urease retained its activity inside molybdenum trioxide sol-gels that are sensitive to ammonia. These hybrid nanoporous composites are useful in the field of biosensors and fuel cells.

Cyclic voltammetry of natural flavonoids on MWNT-modified electrode and their determination in pharmaceuticals

2011 ◽  
Vol 76 (12) ◽  
pp. 1619-1631 ◽  
Author(s):  
Guzel Ziyatdinova ◽  
Ilmira Aytuganova ◽  
Alfiya Nizamova ◽  
Mikhail Morozov ◽  
Herman Budnikov
Keyword(s):  
Cyclic Voltammetry ◽  
Dynamic Range ◽  
Phosphate Buffer Solution ◽  
Cyclic Voltammograms ◽  
Buffer Solution ◽  
Coulometric Determination ◽  
Average Roughness ◽  
Pharmaceutical Dosage Forms ◽  
Force Microscopy ◽  
Relative Standard

The determination of rutin, quercetin and taxifolin in pharmaceutical dosage forms using cyclic voltammetry on multi-walled carbon nanotube modified glassy carbon electrode (MWNT-GCE) has been developed. The surface of the electrode created has been characterized by atomic force microscopy. Electrode modification with MWNT increases the surface average roughness (190-fold) and structures it. There are two oxidation steps at 0.22 and 0.80, 0.23 and 0.80, 0.26 and 0.86 V on cyclic voltammograms of taxifolin, quercetin and rutin, respectively, in phosphate buffer solution of pH 7.4. The linear dynamic range is 1.4–28 and 28–210, 2.0–220 and 0.52–210 μM with detection limits of 0.71, 1.0 and 0.26 μM for rutin, quercetin and taxifolin, respectively. The relative standard deviation of flavonoids determination in pharmaceuticals does not exceed of 7%. The data obtained are in good agreement with coulometric determination.

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