Determination of the optimal conditions for dental subtraction radiography using a storage phosphor system.

The composition, optical characteristics, molar absorption coefficients and equilibrium constants of the reactions of formation of the ML and ML2 complexes of both reagents with cadmium(II) ions were determined by graphical analysis and numerical interpretation of the absorbance-pH curves by the modified SQUAD-G program. Optimal conditions were proposed for the spectrophotometric determination of Cd in 10% v/v ethanol medium in the presence of 0.1% w/v Triton X-100 or 1% w/v Brij 35. BrPADAP and ClPADAP are the most sensitive spectrophotometric reagents for the determination of cadmium(II) ions (ε = 1.28-1.44 . 105 mmol-1 cm2 at 560 nm and pH 8.0-9.5) with a high colour contrast in the reaction (Δλmax ~117 nm) and a selectivity similar to that of other N-heterocyclic azodyes (PAR, PAN, etc.).

Download Full-text

Spectrophotometric study of the reactions of lanthanoids with bromopyrogallol red in the presence of cation active tensides

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19820503 ◽

1982 ◽

Vol 47 (2) ◽

pp. 503-508 ◽

Cited By ~ 2

Author(s):

Irena Němcová ◽

Pavla Plocková ◽

Tran Hong Con

Keyword(s):

Absorption Spectra ◽

Photometric Determination ◽

Spectrophotometric Study ◽

Ternary Complexes ◽

Optimal Conditions ◽

Bromopyrogallol Red ◽

Binary Complexes

The absorption spectra of the binary complexes of lanthanoids with bromopyrogallol red were measured and the formation of ternary complexes with cation active tenside, Septonex, was studied. Optimal conditions were found for the formation of these complexes and the possibility of their use in the photometric determination of lanthanoids was demonstrated on several examples.

Download Full-text

The polarographic and voltammetric determination of 2,6-dicyano-4-nitro-2'-acetylamino-4'-diethylaminoazobenzene

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19901508 ◽

1990 ◽

Vol 55 (6) ◽

pp. 1508-1517 ◽

Cited By ~ 1

Author(s):

Jiří Barek ◽

Dagmar Civišová ◽

Ashutosh Ghosh ◽

Jiří Zima

Keyword(s):

Azo Dye ◽

Differential Pulse ◽

Differential Pulse Polarography ◽

Determination Limit ◽

Polarographic Reduction ◽

Hanging Mercury Drop Electrode ◽

Optimal Conditions ◽

Pulse Polarography ◽

Pulse Voltammetry

The polarographic reduction of the title azo dye was studied and optimal conditions were found for its analytical utilization in the concentration range 1 . 10-6 - 1 . 10-7 mol l-1 using differential pulse polarography and 1 . 10-6 - 1 . 10-8 mol l-1 using fast scan differential pulse voltammetry or linear scan voltammetry at a hanging mercury drop electrode. When the latter technique is combined with adsorptive accumulation of the studied substance on the surface of the hanging mercury drop, the determination limit can be further decreased to 3 . 10-9 mol l-1.

Download Full-text

Manufacturing Process for Extracting Essential Oils from White Pepper (Piper nigrum L.) by Hydrodistillation Technique

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.298.89 ◽

2019 ◽

Vol 298 ◽

pp. 89-93 ◽

Cited By ~ 3

Author(s):

Thien Hien Tran ◽

Thi To Quyen Ngo ◽

Thi Kim Ngan Tran ◽

Tri Duc Lam ◽

Tan Phat Dao ◽

...

Keyword(s):

Essential Oil ◽

Essential Oils ◽

Manufacturing Process ◽

Oil Extraction ◽

Piper Nigrum ◽

Optimal Conditions ◽

Distillation Process ◽

White Pepper ◽

Oil Performance

Vietnam is the world's leading country in growing and producing pepper trees. In this study, we attempted the optimization of white pepper essential oil extraction. The obtained oil was then subject to determination of constituent composition via GC-MS method. The essential oil performance achieved 3.6% by hydro-distillation process with optimal conditions (25 grams of fresh pepper, size 18, 120 minutes extraction, 130°C). A total of 23 volatile constituents were identified from the white pepper essential oil, with the major components being 27.4% of Limonene, 3-Carene 22,928%, Sabinene 17,622%, β-pinene 10.068%, α-Pinene 5.426%.

Download Full-text

The impact of acid hydrolysis conditions on carbohydrate determination in lignocellulosic materials: a case study with Eucalyptus globulus bark

Holzforschung ◽

10.1515/hf-2020-0250 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ricardo Jorge Oliveira ◽

Bruna Santos ◽

Maria J. Mota ◽

Susana R. Pereira ◽

Pedro C. Branco ◽

...

Keyword(s):

Acid Hydrolysis ◽

Eucalyptus Globulus ◽

Industrial Processes ◽

Lignocellulosic Materials ◽

Optimal Conditions ◽

Hydrolysis Conditions ◽

The Impact ◽

Eucalyptus Bark

Abstract Lignocellulosic biomass represents a suitable feedstock for production of biofuels and bioproducts. Its chemical composition depends on many aspects (e.g. plant source, pre-processing) and it has impact on productivity of industrial bioprocesses. Numerous methodologies can be applied for biomass characterisation, with acid hydrolysis being a particularly relevant step. This study intended to assess the most suitable procedures for acid hydrolysis, taking Eucalyptus globulus bark as a case study. For that purpose, variation of temperature (90–120 °C) was evaluated over time (0–5 h), through monosaccharides and oligosaccharides contents and degradation. For glucose, the optimal conditions were 100 °C for 2.5 h, reaching a content of 48.6 wt.%. For xylose, the highest content (15.2 wt.%) was achieved at 90 °C for 2 h, or 120 °C for 0.5 h. Maximum concentrations of mannose and galactose (1.0 and 1.7 wt.%, respectively) were achieved at 90 and 100 °C (2–3.5 h) or at 120 °C (0.5–1 h). These results revealed that different hydrolysis conditions should be applied for different sugars. Using this approach, total sugar quantification in eucalyptus bark was increased by 4.3%, which would represent a 5% increase in the ethanol volume produced, considering a hypothetical bioethanol production yield. This reflects the importance of feedstock characterization on determination of economic viability of industrial processes.

Download Full-text

Micellar Electrokinetic Chromatographic Study of the Separation of an Aromatase Inhibitor and a Tryciclic Antidepressant in the Breast Cancer Treatment

Analytical Chemistry Insights ◽

10.4137/aci.s939 ◽

2008 ◽

Vol 3 ◽

pp. ACI.S939 ◽

Cited By ~ 5

Author(s):

J. Rodríguez Flores ◽

A.M. Contento Salcedo ◽

L. Muñoz Fernández

Keyword(s):

Micellar Electrokinetic Chromatography ◽

Solid Phase ◽

Background Electrolyte ◽

Kinetic Studies ◽

Breast Cancer Treatment ◽

Chromatographic Study ◽

Optimal Conditions ◽

Sodium Dodecylsulphate ◽

Experimental Parameters

Micellar electrokinetic chromatography (MEKC) was investigated for the simultaneous determination of letrozole, imipramine and their metabolites in human urine samples over a concentration range of therapeutic interest. Experimental parameters such as pH of the running electrolyte, sodium dodecylsulphate (SDS) concentration, borate concentration, voltage, etc were investigated. Under optimal conditions of 25 mM SDS, 15 mM borate buffer (pH 9.2), 15% 2-propanol, as background electrolyte; 28 kV and 40 °C, as voltage and cartridge temperature, respectively; resolution between the peaks was greater than 1.7. Before the determination, a solid phase extraction (SPE) procedure with a C18 cartridge was optimized. Good linearity, accuracy, precision, robustness and ruggedness were achieved and detection limits of 12.5 ng/mL for letrozole and its metabolite and 37.5 ng/mL, were obtained for imipramine and their metabolites. Real determinations of these analytes in two patient urines were carried out. Sensitivity achieved in this method is sufficient to perform kinetic studies in humans.

Download Full-text

A Two-step Electrodeposition of Pd-Cu/Cu2O Nanocomposite on FTO Substrate for Non-enzymatic Hydrogen Peroxide Sensor

Current Analytical Chemistry ◽

10.2174/1573411017666210520153409 ◽

2021 ◽

Vol 17 ◽

Author(s):

Ke Huan ◽

Li Tang ◽

Dongmei Deng ◽

Huan Wang ◽

Xiaojing Si ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Cyclic Voltammetry ◽

Photoelectron Spectroscopy ◽

Chemical Structure ◽

Pd Nanoparticles ◽

Optimal Conditions ◽

Potential Oscillation ◽

X Ray Diffraction ◽

X Ray

Background: Hydrogen peroxide (H2O2) is a common reagent in the production and living, but excessive H2O2 may enhance the danger to the human body. Consequently, it is very important to develop economical, fast and accurate techniques for detecting H2O2. Methods: A simple two-step electrodeposition process was applied to synthesize Pd-Cu/Cu2O nanocomposite for non-enzymatic H2O2 sensor. Cu/Cu2O nanomaterial was firstly electrodeposited on FTO by potential oscillation technique, and then Pd nanoparticles were electrodeposited on Cu/Cu2O nanomaterial by cyclic voltammetry. The chemical structure, component, and morphology of the synthesized Pd-Cu/Cu2O nanocomposite were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of Pd-Cu/Cu2O nanocomposite were studied by cyclic voltammetry and amperometry. Results: Under optimal conditions, the as-fabricated sensor displayed a broad linear range (5-4000 µM) and low detection limit (1.8 µM) for the determination of H2O2. The proposed sensor showed good selectivity and reproducibility. Meanwhile, the proposed sensor has been successfully applied to detect H2O2 in milk. Conclusion: The Pd-Cu/Cu2O/FTO biosensor exhibits excellent electrochemical activity for H2O2 reduction, which has great potential application in the field of food safety.

Download Full-text

Determination of optimal conditions for the removal of 4-chlorophenol using several peroxidases in a stirred batch reactor

New Biotechnology ◽

10.1016/j.nbt.2009.06.419 ◽

2009 ◽

Vol 25 ◽

pp. S122-S123

Author(s):

D. Barbosa ◽

J. Bastida ◽

A.M. Hidalgo ◽

M.C. Montiel ◽

S. Ortega ◽

...

Keyword(s):

Batch Reactor ◽

Optimal Conditions

Download Full-text

Determination of chloramphenicol by differential pulse voltammetry at carbon paste electrodes – The use of sodium sulfite for removal of oxygen from electrode surface

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc2011011 ◽

2011 ◽

Vol 76 (5) ◽

pp. 383-397 ◽

Cited By ~ 2

Author(s):

Ferenc T. Pastor ◽

Hana Dejmková ◽

Jiří Zima ◽

Jiří Barek

Keyword(s):

Differential Pulse Voltammetry ◽

Glassy Carbon ◽

Sodium Sulfite ◽

Differential Pulse ◽

Optimal Conditions ◽

Carbon Paste ◽

Tricresyl Phosphate ◽

Carbon Paste Electrodes ◽

Pulse Voltammetry

The possibility of determination of chloramphenicol by differential pulse voltammetry at four different carbon paste electrodes, in the full pH range (2–12) of Britton–Robinson (BR) buffer was investigated. Electrodes were prepared by mixing spectroscopic graphite powder or glassy carbon microbeads with mineral oil (Nujol) or tricresyl phosphate. Under optimal conditions (BR buffer pH 12, the electrode prepared from glassy carbon microbeads and tricresyl phosphate), linear calibration graph was obtained only in 10–5 M chloramphenicol concentration range. Determination of lower concentrations of chloramphenicol was complicated by irreproducible peak of oxygen from the carbon paste which overlapped with peak of chloramphenicol. Addition of sodium sulfite removed the oxygen peak without influence on the peak of chloramphenicol. Under optimal conditions (electrode paste made from glassy carbon microbeads, BR buffer pH 10 and 0.5 M sodium sulfite), straight calibration line was obtained in the 10–6 and 10–5 M chloramphenicol concentration range. Limit of determination was 5 × 10–7 mol/l.

Download Full-text

First Electrochemical Method of Nitrothal-Isopropyl Determination in Water Samples

Journal of Chemistry ◽

10.1155/2016/6045347 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Dariusz Guziejewski ◽

Agnieszka Nosal-Wiercińska ◽

Sławomira Skrzypek ◽

Witold Ciesielski ◽

Sylwia Smarzewska

Keyword(s):

Environmental Samples ◽

Electrochemical Method ◽

Concentration Level ◽

Stripping Voltammetry ◽

Adsorptive Stripping Voltammetry ◽

Hanging Mercury Drop Electrode ◽

Optimal Conditions ◽

Step Potential ◽

Accumulation Time

The aim of the research was the use of square wave adsorptive stripping voltammetry (SWAdSV) in conjunction with a hanging mercury drop electrode (HMDE) for the determination of nitrothal-isopropyl. It was found that optimal SW technique parameters were frequency, 200 Hz; amplitude, 50 mV; and step potential, 5 mV. Accumulation time and potential were studied to select the optimal conditions in adsorptive stripping voltammetry: 45 s at 0.0 V, respectively. The calibration curve (SWSV) was linear in the nitrothal-isopropyl concentration range from 2.0 × 10−7 to 2.0 × 10−6 mol L−1 with detection limit of 3.46 × 10−8 mol L−1. The repeatability of the method was determined at a nitrothal-isopropyl concentration level equal to 6.0 × 10−7 mol L−1 and expressed as RSD = 5.5% (n=6). The proposed method was successfully validated by studying the recovery of nitrothal-isopropyl in spiked environmental samples.

Download Full-text