Quantitative Determination of Natural Rubber Hydrocarbon by Refractive Index Measurements

1952 ◽  
Vol 25 (3) ◽  
pp. 680-688
Author(s):  
Rachel J. Fanning ◽  
Norman Bekkedahl
Keyword(s):  
Refractive Index ◽  
Natural Rubber ◽  
Quantitative Determination ◽  
Original Sample ◽  
Hydrocarbon Content ◽  
Good Grade ◽  
Different Sources ◽  
Better Than

Abstract Rubbers from different sources vary considerably in rubber hydrocarbon content, from 70 per cent or less for some of the wild varieties to about 95 per cent for a good grade of plantation rubber. The quality of a rubber is measured to a great extent by the percentage of rubber hydrocarbon. A new procedure for the quantitative determination of this hydrocarbon has been developed, which involves the measurement of refractive index of a solution of a known weight of acetone-extracted rubber in a known weight of 1-bromonaphthalene. From the observed data and from other previously determined or known physical constants, such as the densities and refractive indexes of the rubber hydrocarbon and the solvent, the percentage of hydrocarbon in the original sample can be calculated. This new method gives results as good as, or better than, other existing methods, and is simpler and less time-consuming to perform.

Determination of Peroxides in Synthetic Rubbers

1945 ◽  
Vol 18 (4) ◽  
pp. 874-876
Author(s):  
Richard F. Robey ◽  
Herbert K. Wiese
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Quantitative Determination ◽  
High Molecular Weight ◽  
Active Oxygen ◽  
Lower Molecular Weight ◽  
Synthetic Rubber ◽  
High Molecular Weight Polymers ◽  
Methanol Solutions

Abstract Peroxides are found in synthetic rubbers either as the result of attack by oxygen, usually from the air, or as a residue from polymerization operations employing peroxide catalysts. Because of possible detrimental effects of active oxygen on the properties of the rubber, a method of quantitative determination is needed. The concentration of peroxides in substances of lower molecular weight may be determined with ferrous thiocyanate reagent, either titrimetrically as recommended by Yule and Wilson or colorimetrically as by Young, Vogt, and Nieuwland. Unfortunately, many highly polymeric substances are not soluble in the acetone and methanol solutions employed in these procedures. This is also the case with hydrocarbon monomers, such as butadiene, containing appreciable concentrations of soluble high molecular weight polymers. Bolland, Sundralingam, Sutton and Tristram recommended benzene as a solvent for natural rubber samples and the reagent made up in methanol. However, most synthetic rubbers are not readily soluble even in this combination. The following procedure employs the ferrous thiocyanate reagent in combination with a solvent capable of maintaining considerable concentrations of synthetic rubber in solution. The solvent comprises essentially 20 per cent ethanol in chloroform.

Quantitative Determination of Copper in Natural Rubber

1953 ◽  
Vol 26 (1) ◽  
pp. 251-256 ◽  
Author(s):  
Lewis T. Milliken
Keyword(s):  
Carbon Tetrachloride ◽  
Natural Rubber ◽  
Quantitative Determination ◽  
Oxidation Process ◽  
Aqueous Suspension ◽  
Wet Oxidation ◽  
Acid Extract ◽  
Organic Solution ◽  
Determination Of Copper

Abstract A procedure is recommended in which small amounts of copper in rubber can be measured quantitatively by determining the depth of color of a copper carbamate complex in a carbon tetrachloride solution. The complex is formed in an alkaline solution prepared from an acid extract of the rubber ashed at 550° C. This procedure yields results which are as reliable as those obtained by the more tedious and time-consuming procedures involving the wet-oxidation process which are at present recommended by standardizing organizations. The use of an organic solution rather than an aqueous suspension gives better reproducibility, permits easier use of a photometer, and reduces the interference due to iron by a factor of ten.

scholarly journals Determination of Effectiveness Absorption of The Rice Husk And Hazelnut Shell to Purification Used Cooking Oil

2019 ◽  
Vol 12 (1) ◽  
pp. 19
Author(s):  
Loth Botahala ◽  
Yanti Malailak ◽  
Herlin Silvia Maure ◽  
Hagar Karlani
Keyword(s):  
Rice Husk ◽  
Activated Charcoal ◽  
Absorption Capacity ◽  
Cooking Oil ◽  
Used Cooking Oil ◽  
Hazelnut Shell ◽  
Hazelnut Shells ◽  
Better Than

The effectiveness of the absorption of activated rice husk and hazelnut shells on the purification of used cooking oil has been carried out. The aim is to determine the absorption capacity of the active charcoal of rice husk and hazelnut shells to purify used cooking oil. After being physically activated, activated charcoal from rice husk and pecan shells is applied to the purification of used cooking oil. The results show that the quality of hazelnut shell charcoal is better than rice husk after it is applied to purifying used cooking oil.

scholarly journals EXTRACTION, HYDROLYSIS, AND ELECTROPHORETIC ANALYSIS OF RIBONUCLEIC ACID FROM MICROSCOPIC TISSUE UNITS (MICROPHORESIS)

1960 ◽  
Vol 8 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Jan-Erik Edström
Keyword(s):  
Quantitative Determination ◽  
Ultraviolet Light ◽  
Coefficient Of Variation ◽  
Ribonucleic Acid ◽  
Single Cells ◽  
Electrophoretic Analysis ◽  
Test Substance ◽  
Different Sources ◽  
Purine Pyrimidine

A procedure for the purine-pyrimidine analysis of RNA in the 100- to 1000 µµg. range is presented. It includes hydrolysis and electrophoretic analysis of RNA, which is extracted from single isolated tissue units, like single cells. The quantitative determination of the separated compounds is carried out by a photographic-photometric procedure in ultraviolet light. The determined values show a coefficient of variation of about ±7 per cent on test substance. Microelectrophoretic analyses of RNA from different sources have been performed and are compared to macrochemical analyses. The agreement is good in those cases in which it is possible to get any information at all through macrochemical analyses.

scholarly journals Herbal Extracts Incorporated into Shortbread Cookies: Impact on Color and Fat Quality of the Cookies

Biomolecules ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 858
Author(s):  
Mariola Kozlowska ◽  
Anna Zbikowska ◽  
Katarzyna Marciniak-Lukasiak ◽  
Malgorzata Kowalska
Keyword(s):  
Room Temperature ◽  
Control Sample ◽  
Herbal Extracts ◽  
Lemon Balm ◽  
Overall Acceptability ◽  
Fat Quality ◽  
Room Temperature Increase ◽  
Better Than

This study aimed at determining the effect of aqueous ethanolic extracts from lemon balm, hyssop and nettle, and butylated hydroxyanisole (BHA) on properties of shortbread cookies. This was achieved by instrumental measurements of color and sensory properties of the cookies directly after baking and by determination of peroxide (PV) and p-anisidine (p-AnV) values, and specific extinction coefficients (K232 and K268 values) for fat extracted from the cookies stored for 3 months at room temperature. Increase of the herbal extracts’ concentration from 0.02% to 0.2% in the cookies caused a reduction of L* (the brightness) and a* values (the red coordinate), while b* values (the yellow coordinate) increased when the cookies were enriched with lemon balm and nettle extracts. Among the cookies studied, those prepared with BHA and 0.1 and 0.2% addition of lemon balm extracts were characterized by the highest scores for aroma, taste, and overall acceptability. Incorporation of BHA and 0.02% hyssop extract into the cookies caused a decrease of PV values (the peroxide value) for fat extracted from the cookies after 3 months of their storage compared to a (control) sample without additives and produced the lowest K232 values. Changes in the p-AnV values for the fat samples studied occurred gradually and slowly during the storage and the obtained values were lower compared to the control sample. All of the studied fat samples also showed a higher ability to scavenge DPPH radicals than the control sample. Considering both PV and p-AnV values as indicators of fat oxidation, BHA protected fat extracted from cookies against oxidation better than the herbal extracts used.

scholarly journals Determination of the Use ofLactobacillus plantarumandPropionibacterium freudenreichiiApplication on Fermentation Profile and Chemical Composition of Corn Silage

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Norafizah Abdul Rahman ◽  
Mohd Ridzwan Abd Halim ◽  
Noraniza Mahawi ◽  
Hazira Hasnudin ◽  
Jameel R. Al-Obaidi ◽  
...  
Keyword(s):  
Crude Protein ◽  
Dry Matter ◽  
Bacterial Culture ◽  
Corn Silage ◽  
Propionibacterium Freudenreichii ◽  
Fermentation Profile ◽  
Silage Quality ◽  
Better Than

Corn was inoculated withLactobacillus plantarumandPropionibacterium freudenreichiisubsp.shermaniieither independently or as a mixture at ensiling, in order to determine the effect of bacterial additives on corn silage quality. Grain corn was harvested at 32–37% of dry matter and ensiled in a 4 L laboratory silo. Forage was treated as follows: bacterial types: B0 (without bacteria-control), B1(L. plantarum), B2 (P. freudenreichiisubsp.shermanii), and B3 (combination ofL. plantarumandP. freudenreichiisubsp.shermanii). Each 2 kg of chopped forage was treated with 10 mL of bacterial culture and allowed to ferment for 27 days. The first experiment determined the most suitable wavelength for detection of bacteria (490 nm and 419 nm for B1 and B2, resp.) and the preferable inoculation size (1 × 105 cfu/g). The second experiment analysed the effect of B1 and B2 applied singly or as a mixture on the fermentation characteristics and quality of corn silage.L. plantarumalone increased crude protein (CP) and reduced pH rapidly. In a mixture withP. freudenreichii, the final pH was the lowest compared to other treatments. As a mixture, inclusion of bacteria resulted in silage with lower digestibility than control. Corn silage treated withL. plantarumorP. freudenreichiieither alone or mixed together produced desirable silage properties; however, this was not significantly better than untreated silage.

scholarly journals СРАВНИТЕЛЬНЫЙ АНАЛИЗ МЕТОДИК КОЛИЧЕСТВЕННОГО ОПРЕДЕЛЕНИЯ АСКОРБИНОВОЙ КИСЛОТЫ В СУБСТАНЦИИ

2019 ◽  
Vol 1 (11(41)) ◽  
pp. 32-36
Author(s):  
Д. Т. Гаибназарова ◽  
Г. У. Тиллаева ◽  
Д. Б. Касимова ◽  
У. М. Тиллаева
Keyword(s):  
Ascorbic Acid ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Comparative Analysis ◽  
Quantitative Determination ◽  
High Performance ◽  
Quantitative Content ◽  
Physicochemical Methods

Increasing requirements for the safety, effectiveness and quality of medicines make it necessary to develop new and improve existing methods for their analysis. As a rule, the quality of substances is ensured by a set of analytical methods that confirm their authenticity, determine the purity and quantitative content of the active substance.In this study, a comparative analysis of the physicochemical methods for the quantitative determination of ascorbic acid in substances is carried out. The advantage of using the method of high performance liquid chromatography over the spectrophotometric method is determined.

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