Determination of Total Sulfur in Rubber and Rubberlike Materials

1943 ◽  
Vol 16 (3) ◽  
pp. 675-678 ◽  
Author(s):  
La Verne E. Cheyney
Keyword(s):  
Nitric Acid ◽  
Perchloric Acid ◽  
Potassium Nitrate ◽  
Potassium Chlorate ◽  
Sodium Peroxide ◽  
Oxide Mixture ◽  
Vulcanized Rubber ◽  
Large Numbers ◽  
Fusion Methods

Abstract The determination of total or combined sulfur in vulcanized rubber and materials of similar type involves numerous difficulties. This fact is attested by the very large number of methods which have been proposed. All the most important methods involve oxidation of the sulfur, in whatever form it may be present, to sulfate and weighing the latter as barium sulfate. The only essential differences lie in the methods of oxidation employed. The methods which seem to be the most popular at the present time are (1) oxidation of the sample in a Parr bomb with sodium peroxide, potassium chlorate, and sugar; (2) oxidation with perchloric acid and nitric acid, sometimes with the additional use of bromine; (3) oxidation with nitric acid and bromine, followed by sodium carbonate-potassium nitrate fusion; and (4) oxidation with nitric acid-zinc oxide mixture, bromine, and potassium chlorate. Serious explosions have been known to occur with perchloric acid oxidations; hence this method is not so popular at present as the other three. The fusion methods are reliable, but they are time-consuming and therefore not convenient when large numbers of samples must be handled.

Determination of Sulfur in Rubber by the Perchloric Acid Method

1929 ◽  
Vol 2 (1) ◽  
pp. 45-55 ◽  
Author(s):  
Edward Wolesensky
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Sulfur Content ◽  
Perchloric Acid ◽  
Steam Bath ◽  
Accurate Method ◽  
Dilute Solution ◽  
Sodium Peroxide ◽  
Rubber Compounds

Abstract In a search for a rapid and accurate method for determining sulfur in rubber it was found that oxidation of the sample by means of sodium peroxide in the Parr bomb is unsatisfactory when the sulfur content of the rubber is low because the samples that can be used for this purpose are too small for accurate results, or, if larger samples are used, the oxidation is incomplete. The use of a mixture of nitric and perchloric acids, as described by Kahane, is also unsatisfactory; but with certain modifications the method may be made to yield very good results, and if fusions are unnecessary, it will save time and labor. The chief modifications recommended are the use of a more dilute solution of nitric acid (equal volumes of the concentrated acid and water), allowing the rubber to dissolve completely on the steam bath before heating more strongly, then heating to gentle boiling until oxidation is complete, and finally destroying the residual nitric acid by means of hydrochloric acid. The use of a larger flask (500 to 800 cc.) is also recommended, and suggestions are also made for the adaptation of this method to the analysis of those rubber compounds which contain barium, lead, etc.

The Perchloric Method for the Determination of Sulfur in Rubber

1934 ◽  
Vol 7 (4) ◽  
pp. 730-735
Author(s):  
Ernest Kahane
Keyword(s):  
Nitric Acid ◽  
Perchloric Acid ◽  
Organic Substance ◽  
Present Author ◽  
General Idea ◽  
Organic Substances ◽  
Gutta Percha ◽  
Higher Temperature ◽  
As If

Abstract The problem of the determination of sulfur in rubber has been dealt with extensively in the literature, and it seems as if discussions and descriptions of new technic are nowhere nearly ended yet. The determination is so essential, and its rapid and precise execution is of such importance in industrial technic, that efforts in this direction should not be regarded as wasted. In 1926 and in 1927 Le Caoutchouc et La Gutta-Percha contained two articles in which the present author discussed the conditions of the determination of sulfur in rubber and then proposed the use of a new oxidizing mixture, not mentioned previous to that time, which involved the destruction of organic substances by perchloric acid. This method consisted simply in the attack on a 1-gram sample of rubber by 10 cc. of nitric acid (d. 1.39) and 5 cc. of perchloric acid (d. 1.61). Upon heating, attack by the nitric acid takes place, and this is followed by evaporation of the excess nitric acid, then at a little higher temperature there is an attack by the perchloric acid, which oxidizes the rest of the organic substance completely. This publication was concerned much more, in the determination of sulfur by the perchloric method, with the general idea of the destruction of organic substances than it was with the precise details of carrying it out. The technic had been studied somewhat superficially, as is shown by the text of the article itself.

The Effects of Acidic Medium on the Sodium Contents Determination by FAAS

2020 ◽  
Vol 1001 ◽  
pp. 139-144
Author(s):  
Ying Li ◽  
Ben Tao Li ◽  
Guang Yu Sun ◽  
Hui Huang ◽  
Chen Gong ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Atomic Absorption Spectrometry ◽  
Flame Atomic Absorption Spectrometry ◽  
Perchloric Acid ◽  
Acidic Medium ◽  
Absorption Spectrometry ◽  
Flame Atomic Absorption ◽  
Acid Effect

The influence of different acidic medium, including hydrochloric acid, nitric acid and perchloric acid on the absorbance of sodium by flame atomic absorption spectrometry was studied. The results showed that the effects of acidic medium and water on the determination of sodium were as follows: hydrochloric acid > perchloric acid > nitric acid > water. Acid effect changed with the increase of acid concentration, however, the absorbance value of sodium element decreased when the concentration of acid was higher than 1%~2%. This effect was more obvious for high content of sodium. The detection limits, repeatability and recovery of the samples under the three acidic medium were compared. The optimum acid conditions were determined and the sensitivity of the method was improved.

Determination of Free Carbon in Rubber. The Cresol Method

1941 ◽  
Vol 14 (1) ◽  
pp. 241-248 ◽  
Author(s):  
J. B. Roberts
Keyword(s):  
United States ◽  
Nitric Acid ◽  
Carbon Content ◽  
Accurate Method ◽  
The United States ◽  
Free Carbon ◽  
Simple Apparatus ◽  
Vulcanized Rubber ◽  
Acid Method

Abstract A simple, accurate method for the determination of free carbon in either raw or vulcanized rubber is presented. It has replaced the nitric acid method entirely in the laboratory of the United States Rubber Company, Detroit, Michigan. A study of the effects of interfering substances, and numerous comparisons of results by the cresol and the nitric acid methods, are given. Results by the cresol method, in the absence of interfering substances, are within 1 per cent of the calculated free carbon content. The method requires only simple apparatus readily available.

Turbidimetry of inorganic sulfate, ester sulfate, and total sulfur in urine.

1980 ◽  
Vol 26 (8) ◽  
pp. 1178-1181 ◽  
Author(s):  
P Lundquist ◽  
J Mårtensson ◽  
B Sörbo ◽  
S Ohman
Keyword(s):  
Polyethylene Glycol ◽  
Nitric Acid ◽  
Perchloric Acid ◽  
Barium Sulfate ◽  
Wet Oxidation ◽  
Total Sulfur ◽  
Sulfate Ester ◽  
Healthy Persons ◽  
Inorganic Sulfate

Abstract We describe simple and precise methods for the determination of inorganic sulfate, ester sulfate, and total sulfur in urine. The methods are based on turbidimetry of sulfate as barium sulfate in the presence of a small amount of preformed barium sulfate and with polyethylene glycol as a stabilizing agent. Inorganic sulfate is directly determined, whereas ester sulfate is measured after removal of inorganic sulfate, followed by acid hydrolysis. Total sulfur is determined after wet oxidation of the sample with nitric acid and perchloric acid in the presence of vanadate as a catalyst. We also report excretion values for healthy persons on a self-selected diet. Men excrete significantly higher amounts of inorganic sulfate and total sulfur than women, but this sex-related difference becomes insignificant if excretion values are expressed relative to creatinine.

Spectrophotometric Determination of Microgram Quantities of Copper in Biologic Materials

1964 ◽  
Vol 10 (9) ◽  
pp. 845-852 ◽  
Author(s):  
Ramon E Stoner ◽  
Waldemar Dasler
Keyword(s):  
Nitric Acid ◽  
Spectrophotometric Determination ◽  
Alkaline Solution ◽  
Perchloric Acid ◽  
Acid Mixture

Abstract A procedure for the determination of microgram quantities of copper in biologic material is described. The sample is wet-ashed with a nitric acid-perchloric acid mixture. The copper is extracted from an alkaline solution of the ash with a solution of diphenylcarbazide in benzene. Absorbance of the red complex is read at 540 mµ. The copper in as little as 0.5 ml. of serum can be determined and the method is suitable for routine determinations. The use of microcells makes possible the analysis of 0.1 ml. of serum.

Determination of Free Carbon in Cured Rubber Stocks

1951 ◽  
Vol 24 (1) ◽  
pp. 224-227
Author(s):  
I. M. Kolthoff ◽  
R. G. Gutmacher
Keyword(s):  
Nitric Acid ◽  
Carbon Black ◽  
Natural Rubber ◽  
Osmium Tetroxide ◽  
Free Carbon ◽  
Vulcanized Rubber ◽  
Tert Butyl Hydroperoxide ◽  
Inorganic Fillers ◽  
Dilute Nitric Acid

Abstract A method for the determination of free carbon in vulcanized rubber stocks is described. The sample is softened in boiling p-dichlorobenzene before treatment with tert-butyl hydroperoxide in the presence of osmium tetroxide. No difficulties are encountered in the filtration of the carbon black. The carbon black is washed on the filter with dilute nitric acid to remove acid-soluble inorganic fillers. The method has been successfully applied to natural rubber, GR-S, Butyl rubber, and Neoprene. No correction is necessary.

Determination of Phosphorus in Fruits and Fruit Products by a Spectrophotometry Molybdovanadate Method and by the Official Gravimetric Quinoline Molybdate Fertilizer Method

1969 ◽  
Vol 52 (4) ◽  
pp. 865-870
Author(s):  
Ben Estrin ◽  
Wallace S Brammell
Keyword(s):  
Nitric Acid ◽  
Perchloric Acid ◽  
Colorimetric Method ◽  
Volumetric Method ◽  
Dry Ashing ◽  
Ash Weight ◽  
Molybdate Method ◽  
Phosphorus Determination ◽  
Good Agreement

Abstract A newly developed spectrophotometric molybdovanadate method and the official gravimetric quinoline molybdate fertilizer method, 2.025(b), slightly modified, were used to determine phosphorus in fruits and fruit products. In the former method, the use of hazardous perchloric acid is avoided by dry-ashing the sample as in method 20.017 and by using nitric acid rather than perchloric acid in the molybdovanadate reagent. In the quinoline molybdate method, the sample is dry-ashed in the same way. In both proposed methods, the official ash solution is used for the phosphorus determination as in the official volumetric method, 20.031–20.032. Ash weight can be obtained before preparing this solution; in the official colorimetric method, however, a second aliquot must be dry-ashed for the ash weight. The two proposed methods gave results in good agreement with those obtained by the official volumetric method. These methods are simpler and faster than the two present official methods.

Simple, Rapid Digestion Technique for the Determination of Mercury in Fish by Flameless Atomic Absorption

1972 ◽  
Vol 55 (4) ◽  
pp. 741-742 ◽  
Author(s):  
Walter Holak ◽  
Benjamin Krinitz ◽  
John C Williams
Keyword(s):  
Nitric Acid ◽  
Atomic Absorption ◽  
Perchloric Acid ◽  
Closed System ◽  
Acid Digestion ◽  
Flameless Atomic Absorption ◽  
Digestion Technique ◽  
Mercury In Fish

Abstract A simple and rapid digestion technique is described for the determination of mercury in fish by flameless atomic absorption. The sample is digested with nitric acid in a closed system in a commercially available vessel made of Teflon. A 30 min digestion at 150 °C is sufficient to convert the mercury to an inorganic form so that it can t h e n be reduced to the elemental state , aerated, and determined by atomic absorption. The proposed digestion compares favorably with the official AOAC sulfuricnitric- perchloric acid digestion.

Determination of Free Sulfur in Vulcanized Rubber

1942 ◽  
Vol 15 (2) ◽  
pp. 376-377
Author(s):  
J. G. Mackay ◽  
C. H. J. Avons
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Barium Sulfate ◽  
Barium Chloride ◽  
Acetone Extract ◽  
Volumetric Method ◽  
Watch Glass ◽  
Rubber Industry ◽  
Vulcanized Rubber

Abstract The following comments pertain to a paper of the above title by Mackay and Avons, published in Transactions of the Institution of the Rubber Industry, Vol. 16, pages 117–122, October 1940, and reprinted in Rubber Chemistry and Technology, Vol. 14, pages 520–524, April 1941. H. P. Stevens draws attention to the penultimate paragraph on p. 522 in which it is pointed out that the bromine method of oxidation is tedious and the reagent unhealthful, whereas perchloric acid may be dangerous. As a result of many years experience he is of the opinion that neither reagent is necessary. After adding nitric acid to the acetone extract in the flask, which should be covered with a watch glass, and when the reaction has subsided, about 0.5 gram of potassium chlorate is added and the mixture kept warm at 50 to 60° C. The top of a water oven is convenient; but the heating must be limited, as the yellow oxides of chlorine are rapidly driven off near 100°, and the liquid changes back from yellow to orange. The flask can be left to itself for an hour or two, but further addition of chlorate may be necessary to complete the oxidation. The contents are evaporated to dryness and taken up twice with concentrated hydrochloric acid preparatory to precipitation with barium chloride. A volumetric method may be preferable when a large number of routine tests have to be made, otherwise the final estimation can be made as barium sulfate.

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