Application of an improved ultraviolet spectrophotometry technology for the determination of antioxidants in natural ester liquids

2021 ◽  
Author(s):  
Wei Peng ◽  
Mingxiang Xiong ◽  
Xianqin Deng ◽  
Zhiyan Peng ◽  
Wu Lu ◽  
...  
Keyword(s):  
Ultraviolet Spectrophotometry ◽  
Natural Ester

Studies on the Behavior Some Paints in Electro-insulating Fluid Based on Vegetable Esters

2018 ◽  
Vol 69 (5) ◽  
pp. 1139-1144
Author(s):  
Iosif Lingvay ◽  
Adriana Mariana Bors ◽  
Livia Carmen Ungureanu ◽  
Valerica Stanoi ◽  
Traian Rus
Keyword(s):  
Structural Changes ◽  
Oxidation Processes ◽  
High Oleic ◽  
Painting Materials ◽  
Insulating Paper ◽  
Different Types ◽  
Mechanism And Kinetics ◽  
Kinetics Of ◽  
Natural Ester

For the purpose of using three different types of painting materials for the inner protection of the transformer vats, their behavior was studied under actual conditions of operation in the transformer (thermal stress in electro-insulating fluid based on the natural ester in contact with copper for electro-technical use and electro-insulating paper). By comparing determination of the content in furans products (HPLC technique) and gases formed (by gas-chromatography) in the electro-insulating fluid (natural ester with high oleic content) thermally aged at 130 �C to 1000 hours in closed glass vessels, it have been found that the presence the investigated painting materials lead to a change in the mechanism and kinetics of the thermo-oxidation processes. These changes are supported by oxygen dissolved in oil, what leads to decrease both to gases formation CO2, CO, H2, CH4, C2H4 and C2H6) and furans products (5-HMF, 2-FOL, 2 -FAL and 2-ACF). The painting materials investigated during the heat treatment applied did not suffer any remarkable structural changes affecting their functionality in the electro-insulating fluid based on vegetable esters.

Quantitative Determination of Benzaldehyde in Flavors and Cordials by Ultraviolet Spectrophotometry and 2,4-Dinitrophenylhydrazine Precipitation

1967 ◽  
Vol 50 (2) ◽  
pp. 319-322
Author(s):  
Richard L Brunelle
Keyword(s):  
Quantitative Determination ◽  
Spectrophotometric Method ◽  
Alternative Methods ◽  
Ultraviolet Spectrophotometry ◽  
Precipitation Procedure ◽  
Gravimetric Procedure

Abstract Three sets of samples were collaboratively analyzed by the official, first action ultraviolet spectrophotometric and 2,4-dinitrophenylhydrazine precipitation methods for determining benzaldehyde in flavors and cordials. The spectrophotometric method was unchanged, except for clarification, and collaborators reported recoveries averaging nearly 100%. The gravimetric procedure using 2,4-dinitrophenylhydrazine gave unsatisfactory recoveries on the first two sets of collaborative samples. However, collaborators reported approximately 96% recovery of benzaldehyde with a modified precipitation procedure on a third set of samples. The ultraviolet spectrophotometric method and the modified 2,4-dinitrophenylhydrazine precipitation procedure are recommended for adoption as official, final action as alternative methods.

UV Determination of Sulfoxide in Formulations

1965 ◽  
Vol 48 (3) ◽  
pp. 569-573
Author(s):  
J B Haus ◽  
L Manolev ◽  
R W Price
Keyword(s):  
Silicic Acid ◽  
Column Chromatography ◽  
The Other ◽  
Ultraviolet Spectrophotometry

Abstract A method for the assay of sulfoxide in insectieidal formulations involves separation of the sulfoxide from the other components by column chromatography on silicic acid with three successive eluting solutions: chloroform; 2% acetone in chloroform; and 10% acetone in chloroform. Sulfoxide is removed in the last eluate and is determined by ultraviolet spectrophotometry. Solvents, emulsifiers, pyrethrins, compounds related to sulfoxide, and other insecticides tested are separated by the column.

Determination of Nicotine in Feeds

1964 ◽  
Vol 47 (2) ◽  
pp. 226-228
Author(s):  
David E Root
Keyword(s):  
Aqueous Phase ◽  
Steam Distillation ◽  
Animal Feed ◽  
Collaborative Study ◽  
Basic Solution ◽  
Ultraviolet Spectrophotometry

Abstract Nicotine, used in medicated animal feed in combination with phenothiazine, dibutyl tin dilaurate, and 2,2'-dihydroxy-5,5’-dichlorophenyl methane, has been successfully isolated from these compounds and the feed interferences and cleaned up by extraction with 0.5% NaOH, steam distillation f r om this basic solution, and extraction from the aqueous phase with chloroform. The nicotine is then partitioned into 0.05iV HC1, and determined by ultraviolet spectrophotometry. A collaborative study yielded 9 0% over-all recoveries, and the method is recommended for adoption as official, first action.

Study on Determination of Glucose in Amylofermentation Liquid Using Ultraviolet Spectrophotometry

2012 ◽  
Vol 538-541 ◽  
pp. 2434-2437 ◽  
Author(s):  
Bao Shan He ◽  
Na Gao ◽  
Fang Wei ◽  
Qi Yu Lu
Keyword(s):  
Hydrogen Peroxide ◽  
Glucose Oxidase ◽  
Optical Method ◽  
Maximum Absorption ◽  
Ultraviolet Spectrophotometry ◽  
Titanyl Oxalate ◽  
Maximum Absorption Wavelength ◽  
Absorption Wavelength

In the presence of glucose oxidase, glucose in samples was oxygenated to hydrogen peroxide, the solution turned from colourless to yellow upon the reaction of potassium titanyl oxalate to the generated hydrogen peroxide. Using ultraviolet spectrophotometry, a new optical method for detecting glucose in amylofermentation liquid has been established. Results demonstrated that glucose concentrations were proportional to absorbance at the maximum absorption wavelength of 380 nm. A favorable linearity was presented in the range of 1 mmol/L to 60 mmol/L. The linear coeffciency was 0.993. This method was simple, reliable, and could be used for determing glucose in samples.

Determination of Biphenyl in Citrus Fruits by Thin Layer Chromatography and Ultraviolet Spectrophotometry

1967 ◽  
Vol 50 (4) ◽  
pp. 934-938
Author(s):  
Paul E Corneliussen
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Uv Light ◽  
Preparative Thin Layer Chromatography ◽  
Mean Deviation ◽  
Citrus Fruits ◽  
Ultraviolet Spectrophotometry ◽  
Spectrophotometric Measurement ◽  
Layer Chromatography

Abstract A rapid method for determining biphenyl in citrus fruits has been developed and was studied collaboratively. Biphenyl is separated from fruit tissue by steam liquidliquid extraction. The ra-heptane extract is subjected to preparative thin layer chromatography (TLC) on plates coated with silica gel containing phosphors for ready visibility of the biphenyl spots under UV light. The spots are removed from the plate and extracted with alcohol for spectrophotometric measurement at 248 mμ. The TLC cleanup adds specificity to the method; o-phenylphenol, if present, does not interfere and crop blanks are insignificant. The average of 36 recoveries (12 each at abovit 100, 50, and 10 ppm) was 96.7% with a mean deviation of 10.7%. It is recommended that the method be adopted as official, first action.

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