scholarly journals In-Situ Formation of Modified Nickel–Zinc-Layered Double Hydroxide Followed by HPLC Determination of Neonicotinoid Insecticide Residues

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 43
Author(s):  
Jitlada Vichapong ◽  
Rawikan Kachangoon ◽  
Rodjana Burakham ◽  
Yanawath Santaladchaiyakit ◽  
Supalax Srijaranai
Keyword(s):  
Limit Of Detection ◽  
Sodium Dodecyl ◽  
The European Union ◽  
Precipitate Phase ◽  
Insecticide Residues ◽  
Nickel Zinc ◽  
Neonicotinoid Insecticide ◽  
In Situ Formation

A single-step preconcentration procedure using the in-situ formation of modified nickel–zinc-layered double hydroxides (LDHs) prior to high-performance liquid chromatography (HPLC) is investigated for the determination of neonicotinoid insecticide residues in honey samples. The LDHs could be prepared by the sequential addition of sodium hydroxide, sodium dodecyl sulfate, nickel nitrate 6-hydrate and zinc nitrate 6-hydrate, which were added to the sample solution. The co-precipitate phase and phase separation were obtained by centrifugation, and then the precipitate phase was dissolved in formic acid (concentrate) prior to HPLC analysis. Various analytical parameters affecting extraction efficiency were studied, and the characterization of the LDHs phase was performed using Fourier-transformed infrared spectroscopy and scanning electron microscopy. Under optimum conditions, the limit of detection of the studied neonicotinoids, in real samples, were 30 μg L−1, for all analytes, lower than the maximum residue limits established by the European Union (EU). The developed method provided high enrichment, by a factor of 35. The proposed method was utilized to determine the target insecticides in honey samples, and acceptable recoveries were obtained.

scholarly journals Determination of Simvastatin by Voltammetry Method at Screen-Printed Electrode Modified by Graphene Oxide Nanosheets and Sodium Dodecyl Sulfate

2022 ◽  
Author(s):  
Abolfazl Darroudi ◽  
Saeid Nazari ◽  
Seyed Ali Marashi ◽  
Mahdi Karimi-Nazarabad
Keyword(s):  
Graphene Oxide ◽  
Sodium Dodecyl Sulfate ◽  
Limit Of Detection ◽  
Sodium Dodecyl ◽  
Screen Printed Electrode ◽  
Support Electrolyte ◽  
Limit Of Quantitation ◽  
Dodecyl Sulfate ◽  
Screen Printed

Abstract An accurate, rapid, simple, and novel technique was developed to determine simvastatin (SMV). In this research, a screen-printed electrode (SPE) was deposited with graphene oxide (GO) and sodium dodecyl sulfate (SDS), respectively. For the first time, the handmade modified SPE measured the SMV by differential pulse voltammetry (DPV) with high sensitivity and selectivity. The results of cyclic voltammetry indicated the oxidation irreversible process of SMV. Various parameters (pH, concentration, scan rate, support electrolyte) were performed to optimize the conditions for the determination of SMV. Under the optimum experiment condition of 0.1 M KNO3 as support electrolyte and pH 7.0, the linear range was achieved for SMV concentration from 1.8 to 36.6 µM with a limit of detection (LOD), and a limit of quantitation (LOQ) of 0.06 and 1.8 µM, respectively. The proposed method was successfully utilized to determine SMV in tablets and urine samples with a satisfactory recovery in the range of 96.2 to 103.3%.

scholarly journals Micellar Liquid Chromatographic Determination of Carbaryl and 1-Naphthol in Water, Soil, and Vegetables

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Mei-Liang Chin-Chen ◽  
Maria Rambla-Alegre ◽  
Abhilasha Durgbanshi ◽  
Devasish Bose ◽  
Sandeep K. Mourya ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Limit Of Detection ◽  
Cetylpyridinium Chloride ◽  
Sodium Dodecyl ◽  
Chromatographic Determination ◽  
Limit Of Quantification ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

A liquid chromatographic procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite 1-naphthol, using a C18 column (250’mm’ × ’4.6’mm) with a micellar mobile phase and fluorescence detection at maximum excitation/emission wavelengths of 225/333’nm, respectively. In the optimization step, surfactants sodium dodecyl sulphate (SDS), Brij-35 andN-cetylpyridinium chloride monohydrate, and organic solvents propanol, butanol, and pentanol were considered. The selected mobile phase was 0.15’M SDS-6% (v/v)-pentanol-0.01’M NaH2PO4buffered at pH 3. Validation studies, according to the ICH Tripartite Guideline, included linearity (r>0.999), limit of detection (5 and 18’ng mL-1, for carbaryl and 1-naphthol, resp.), and limit of quantification (15 and 50’ng mL-1, for carbaryl and 1-naphthol, resp.), with intra- and interday precisions below 1%, and robustness parameters below 3%. The results show that the procedure was adequate for the routine analysis of these two compounds in water, soil, and vegetables samples.

A Facile In-Situ Development of L-Valine Film onto the Surface of Carbon Paste Electrode Towards the Detection of Environmentally Hazardous 4-Amino Phenol

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
T. Venu Gopal ◽  
Tukiakula Madhusudana Reddy ◽  
P. Shaikshavali ◽  
G. Venkataprasad ◽  
P. Gopal
Keyword(s):  
Cyclic Voltammetry ◽  
Carbon Paste Electrode ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Small Scale ◽  
Carbon Paste ◽  
Relative Standard ◽  
Paste Electrode

Abstract A small scale of environmentally hazardous 4-aminophenol can show significant impact on human health. Hence, in the present work, we have designed L-Valine film (Vf) modified carbon paste electrode (Vf/CPE) for the determination of 4-aminophenol. Herein, a facile in-situ L-Valine film was developed by electrochemical polymerization method onto the surface of bare carbon paste electrode (BCPE) with the help of cyclic voltammetry (CV) technique. A two-folds of electrochemical peak current enhancement was achieved at Vf/CPE in comparison with BCPE towards the determination of 4-aminophenol in optimum pH 7.0 of phosphate buffer solution (PBS). This was achieved due to the large surface area and conductive nature of Vf/CPE, which was concluded through the techniques of cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The effect of pH of buffer and scan rate studies were successfully studied. Morphological changes of BCPE and Vf/CPE was studied with the help of scanning electron microscopy (SEM). The formation of Vf on CPE was also analyzed by Fourier transform infrared (FTIR) spectra. Under the optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) values of 4-aminophenol were estimated with the aid of chronoamperometry (CA) technique and was found to be 9.8 μM and 32 μM, respectively. Finally the proposed method was found to have satisfactory repeatability, reproducibility and stability results with low relative standard deviation (RSD) values.

scholarly journals Analysis of Nucleation and Glass Formation by Chip Calorimetry

2021 ◽  
Vol 11 (16) ◽  
pp. 7652
Author(s):  
Meng Gao ◽  
Chengrong Cao ◽  
John H. Perepezko
Keyword(s):  
Differential Scanning Calorimetry ◽  
Crystal Nucleation ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Chip Calorimetry ◽  
In Situ Formation ◽  
Materials Behavior

The advent of chip calorimetry has enabled an unprecedented extension of the capability of differential scanning calorimetry to explore new domains of materials behavior. In this paper, we highlight some of our recent work: the application of heating and cooling rates above 104 K/s allows for the clear determination of the glass transition temperature, Tg, in systems where Tg and the onset temperature for crystallization, Tx, overlap; the evaluation of the delay time for crystal nucleation; the discovery of new polyamorphous materials; and the in-situ formation of glass in liquid crystals. From these application examples, it is evident that chip calorimetry has the potential to reveal new reaction and transformation behavior and to develop a new understanding.

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 Nitrate-Selective Electrodes Based on the Trinuclear Chromium(III) Pivalates

2008 ◽  
Vol 3 (1) ◽  
pp. 44-47 ◽  
Author(s):  
Mihail Revenco ◽  
Mariana Martin ◽  
Waell A.A. Dayyih
Keyword(s):  
Vinyl Chloride ◽  
Limit Of Detection ◽  
Polymeric Matrix ◽  
Nitrate Anion ◽  
Electroactive Material ◽  
Poly Vinyl Chloride ◽  
Different Types

The paper describes the analytical potentialities of the trinuclear chromium(III) complexes as potentiometric ionophores for the construction of electrodes sensitive to the presence of nitrate anion. The electroactive material containing 4,4’-bipyridil was synthesized in situ. The membrane was prepared using dioctylphthalate as a solvent mediator and poly (vinyl chloride) as a polymeric matrix. The electrodes presented a slope of 56 mV/decade, a low limit of detection (3,2.10-6 mol/l), an adequate lifetime (4 months), and suitable selectivity characteristics when compared with other nitrate electrodes. The good parameters of this electrode made possible its application to the determination of nitrate in different types of fertilizers.

scholarly journals Optimized Protocol for the In Situ Derivatization of Glutathione with N-Ethylmaleimide in Cultured Cells and the Simultaneous Determination of Glutathione/Glutathione Disulfide Ratio by HPLC-UV-QTOF-MS

Metabolites ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 292
Author(s):  
Xueni Sun ◽  
Raffaela S. Berger ◽  
Paul Heinrich ◽  
Ibtissam Marchiq ◽  
Jacques Pouyssegur ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Limit Of Detection ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Internal Standard ◽  
Glutathione Disulfide ◽  
Optimized Protocol ◽  
In Situ Derivatization ◽  
In Cells

Glutathione (GSH) and glutathione disulfide (GSSG) are commonly used to assess the oxidative status of a biological system. Various protocols are available for the analysis of GSH and GSSG in biomedical specimens. In this study, we present an optimized protocol for the in situ derivatization of GSH with N-ethylmaleimide (NEM) to prevent GSH autooxidation, and thus to preserve the GSH/GSSG ratio during sample preparation. The protocol comprises the incubation of cells in NEM containing phosphate buffered saline (PBS), followed by metabolite extraction with 80% methanol. Further, to preserve the use of QTOF-MS, which may lack the linear dynamic range required for the simultaneous quantification of GSH and GSSG in non-targeted metabolomics, we combined liquid chromatographic separation with the online monitoring of UV absorbance of GS-NEM at 210 nm and the detection of GSSG and its corresponding stable isotope-labeled internal standard by QTOF-MS operated with a 10 Da Q1 window. The limit of detection (LOD) for GS-NEM was 7.81 µM and the linear range extended from 15.63 µM to 1000 µM with a squared correlation coefficient R2 of 0.9997. The LOD for GSSG was 0.001 µM, and the lower limit of quantification (LLOQ) was 0.01 µM, with the linear (R2 = 0.9994) range extending up to 10 µM. The method showed high repeatability with intra-run and inter-run coefficients of variation of 3.48% and 2.51% for GS-NEM, and 3.11% and 3.66% for GSSG, respectively. Mean recoveries of three different spike-in levels (low, medium, high) of GSSG and GS-NEM were above 92%. Finally, the method was applied to the determination of changes in the GSH/GSSG ratio either in response to oxidative stress in cells lacking one or both monocarboxylate transporters MCT1 and MCT4, or in adaptation to the NADPH (nicotinamide adenine dinucleotide phosphate) consuming production of D-2-hydroxyglutarate in cells carrying mutations in the isocitrate dehydrogenase genes IDH1 and IDH2.

Simultaneous Determination of Cationic and Anionic Surfactants in Domestic, Sewage and River Effluent by Diffuse Reflectance -Fourier Transform Infrared Spectroscop ic Analysis

2021 ◽  
Vol 30 (1) ◽  
pp. 32-40 ◽  
Author(s):  
Ramsingh Kurrey ◽  
Kaushlya Thakur ◽  
Swati Chandrawanshi ◽  
Manas Kanti Deb
Keyword(s):  
Fourier Transform ◽  
Standard Deviation ◽  
Simultaneous Determination ◽  
Diffuse Reflectance ◽  
Limit Of Detection ◽  
Sodium Dodecyl ◽  
Fourier Transform Infrared ◽  
Domestic Sewage ◽  
Relative Standard

A new, simple, rapid and precise novel hyphenated diffuse reflectance-Fourier transform infrared spectroscopy (DRS-FTIR) technique for the simultaneous determination of the most frequently used cationic surfactants (CS+) i.e. cetyltrimethylammonium bromide (CTAB) and anionic surfactant (AS-) i.e. sodium dodecyl sulphate (SDS) in domestic, sewage and river wastewater samples has been stabilised. CS+ and AS- were analyzed using DRS-FTIR, the most steady and strongest vibrational IR peak at 2917.13 cm-1 for CTAB and 1226.07 for SDS were selected for the simultaneous quantiflcation of CS+ and AS- under the optimized condition such as effect of samples volume and effect of temperature. The limit of detection (LOD) and limit of quantiflcation (LOQ) of the present method were 5 µg/mL and 15 µg/mL, respectively. The absorbance and peak area were determined by the DRS-FTIR method, which shows excellent linearity with a correlation coefflcient value of 0.985 and 0.981 for the concentration range of 10-100 µg/mL. The standard deviation (SD) and relative standard deviation (RSD) for six replicate measurements were found to be 0.052 µg/L and 2.8 %, respectively.

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