The Determination of Free Sulfur in Vulcanizates by a Polarographic Method

1952 ◽  
Vol 25 (1) ◽  
pp. 161-166 ◽  
Author(s):  
F. C. J. Poulton ◽  
L. Tarrant
Keyword(s):  
Quantitative Determination ◽  
Acetone Extract ◽  
Polarographic Method ◽  
The Common ◽  
Free Sulfur ◽  
Working Processes

Abstract The polarographic method offers a rapid and accurate means of determining the “true” free sulfur in vulcanizates. In the case of single estimations, the test takes approximately as long as the copper-spiral method, but for multiple or replicate testing it is much quicker. Since the determination is made directly on the acetone extract, it was necessary to examine at some length the possibility of interference from other ingredients of the extract. It is shown that most of the common accelerators and antioxidants are not likely to interfere, and promising methods of determining certain of these substances were revealed. Thus MBT, MBTS, TCA, A11, ONV, ZDC, TMT, TET, Ureka, and some of the Nonox series of antioxidants give regular Polarographic waves readily distinguishable from that of sulfur, and the development of working processes for their determination should not present any great difficulties. Other accelerators and antioxidants, notably ZIX, some Nonox antioxidants and Agerite White, while showing Polarographic activity, give poor curves in the pyridine electrolyte. No doubt in other base solutions the form of curve could be improved, and their quantitative determination would then follow.

scholarly journals Quantitative Determination of Terramycin by Polarographic Method

1955 ◽  
Vol 4 (1) ◽  
pp. 30-34 ◽  
Author(s):  
TAKEJI NOTO ◽  
GAKU MATSUOKA
Keyword(s):  
Quantitative Determination ◽  
Polarographic Method

scholarly journals Composition of Essential Oils in Turmeric Rhizome

2016 ◽  
Vol 16 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Laxmi Devkota ◽  
Meena Rajbhandari
Keyword(s):  
Chemical Composition ◽  
Essential Oil ◽  
Thin Layer ◽  
Quantitative Determination ◽  
Essential Oils ◽  
Colorimetric Method ◽  
Acetone Extract ◽  
Caryophyllene Oxide ◽  
Finger Printing

Turmeric has been recognized as a pharmaceutical crop. It is valuable primarily for essential oil and curcumin content. Chemical composition of the essential oils obtained from the rhizome of turmeric was determined by GC/MS technique. More than 75 compounds were detected and 67 of them were identified. They accounted for 98.59% of essential oil. The essential oil contained 15 monoterpenes (5.58%), 43 sesquiterpenes (84.37%) and 10 nonterpenic components (8.64%). The major constituents were ß-turmeron, a-turmeron, Epi-a-patschutene, ß-sesquiphellandrene, 1,4-dimethyl-2-isobutylbenzene, (±)-dihydro-ar-turmerone, zingiberene, E-a-atlantone and (-)-caryophyllene oxide. Thin layer chromatographic finger printing and quantitative determination of phenolics in acetone extract of commercially available turmeric samples were carried out using Folin-Ciocalteu colorimetric method. Gallic acid was used as the standard for the estimation of phenolics. All the investigated turmeric extracts contained relatively high amount of phenolics.Nepal Journal of Science and Technology Vol. 16, No.1 (2015) pp. 87-94

The Determination of Free Sulfur by a Volumetric Method Part II

1933 ◽  
Vol 6 (4) ◽  
pp. 512-517
Author(s):  
W. D. Guppy
Keyword(s):  
Hydrogen Sulfide ◽  
Organic Compounds ◽  
Sulfur Compounds ◽  
Acetone Extract ◽  
Volumetric Method ◽  
Organic Sulfur Compounds ◽  
Vulcanized Rubber ◽  
Volumetric Determination ◽  
Free Sulfur

Abstract 1. The method previously described for the volumetric determination of free sulfur in vulcanized rubber has been compared with the older gravimetric methods in cases where other organic compounds containing sulfur are present in the vulcanizate. 2. The volumetric method gave lower results than the methods involving oxidation of the acetone extract in the case of vulcanized rubber containing aldehydeamine condensation products of thiouram disulfide compounds. This indicated that the sulfur combined with some organic compounds was not reduced by the reagents used. 3. The results with the accelerator tetraethylthiouram disulfide showed that in some cases part of the sulfur in organic compounds was reduced under the conditions of the reaction. 4. The acetone-soluble and the acetone-insoluble portions of brown substitute contain organic sulfur compounds. Part of the sulfur in these compounds was reduced to hydrogen sulfide by the action of nascent hydrogen. 5. The sulfur compounds present in white substitute were stable toward the reducing agents used in the estimation of free sulfur. 6. The sulfur compounds formed by the vulcanization of ebonite were in part reduced to hydrogen sulfide with tin and acid. Variations in the composition of the mixing and in the vulcanizing conditions altered the amount of these reducible compounds. 7. The volumetric method previously described cannot be used for the determination of the free sulfur in ebonite, brown substitute or in vulcanized rubber containing brown substitute. In the case of vulcanized rubber containing brown substitute or of ebonite the method can be used to determine the amount of sulfur in the acetone extract. 8. The volumetric method can be employed for the determination of the free sulfur in soft vulcanized rubber containing white substitute and in reclaimed rubber.

The Quantitative Determination of Rubber Chemicals

1957 ◽  
Vol 30 (4) ◽  
pp. 1017-1026 ◽  
Author(s):  
Otto Lorenz ◽  
Elisabeth Echte
Keyword(s):  
Quantitative Determination ◽  
Chloride Solution ◽  
Silver Salt ◽  
Stannous Chloride ◽  
Zinc Salt ◽  
Iodine Solution ◽  
Experimental Conditions ◽  
Zinc Salts ◽  
Free Sulfur

Abstract 1. Both the precipitation of mercaptobenzothiazole as a silver salt and its oxidation with an iodine solution to a disulfide may be utilized for quantitative determination. 2. Zinc benzothiazolyl mercaptide can be determined iodometrically, either directly or indirectly, after being cleaved by acids. 3. Benzothiazolyl disulfide is determined as mercaptobenzothiazole after reduction with acidic stannous chloride solution. 4. A procedure for the determination of a mixture of mercaptobenzothiazole, zinc benzothiazolyl mercaptide, and dibenzothiazolyl disulfide is described. 5. Experimental conditions are indicated, under which the quantitative determination of free sulfur is possible in the presence of mercaptobenzothiazole, its zinc salt, the disulfide, and the zinc salts of fat acids. In all cases the uncombined sulfur is determined after its conversin to thiocyanate by an argentometric conductivity titration of the thiocyanate.

scholarly journals A New Approach for the Determination of Benzocaine and Procaine in Pharmaceuticals by Single-Sweep Polarography

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Serhij Plotycya ◽  
Oksana Strontsitska ◽  
Solomiya Pysarevska ◽  
Mykola Blazheyevskiy ◽  
Liliya Dubenska
Keyword(s):  
Quantitative Determination ◽  
Oxidation Products ◽  
Polarographic Reduction ◽  
Polarographic Method ◽  
Experimental Conditions ◽  
New Approach ◽  
Reduction Current ◽  
Product Specifications ◽  
Good Agreement

A new polarographic method for the determination of benzocaine and procaine based on the polarographic reduction of their chemically obtained oxidation products with potassium peroxymonosulfate is developed. Experimental conditions affecting quantitative yield of benzocaine and procaine oxidation products such as рH, oxidation time, reagents’ concentration, and temperature are explored. It is shown that the reduction current changes in a linear fashion (R=0.999) with increasing concentration of anesthetics over a concentration range of 1·10−6 - 5·10−5 mol L−1. The calculated limits of detection (LOD) for benzocaine and procaine are found to be 5.6·10−6 and 6·10−6 mol L−1, respectively. In the present study, quantitative polarographic determination of benzocaine in Farisil tablets and “Septolete Plus” lozenges and procaine in solution for injections is performed. The results of the analysis are in good agreement with the product specifications described in the quality certificates. The possibility of quantitative determination of benzocaine and procaine in pharmaceuticals is confirmed.

The Volumetric Determination of Free Sulfur

1933 ◽  
Vol 6 (3) ◽  
pp. 412-413 ◽  
Author(s):  
A. Castiglioni
Keyword(s):  
Silver Nitrate ◽  
Nitrate Solution ◽  
Potassium Cyanide ◽  
Silver Nitrate Solution ◽  
Potassium Thiocyanate ◽  
Acetone Extract ◽  
Red Color ◽  
Volumetric Determination ◽  
Free Sulfur

Abstract In order to determine free sulfur in substances like rubber and antimony sulfide, extraction is carried out with a solvent, preferably acetone. After separation from the solvent, the extracted sulfur is converted into the sulfate and weighed as barium sulfate. With the object of making this determination, easier and simpler, it occurred to the author to determine the sulfur in the acetone extract volumetrically, instead of gravimetrically, by utilizing the observed fact that potassium thiocyanate is formed when the acetone extract is boiled with potassium cyanide. Experimental investigation of this subject showed that in the presence of an excess of potassium cyanide, conversion of the sulfur into potassium thiocyanate is quantitative, so that after evaporation of the solvent a mixture of potassium cyanide and potassium thiocyanate remains behind. To determine the potassium thiocyanate in the aqueous solution of these two salts, the method of Schulek (cf. Z. anal. Chem., 65, 433 (1924–25)) was used, which is based on the decomposition of potassium cyanide by formaldehyde. Instead, however, of adding an excess of titrated silver nitrate solution, as recommended by Schulek, and then determining the excess silver by the Volhard method, the titration was carried out directly with the silver nitrate solution, using iron nitrate as indicator, until the blood-red color of ferric thiocyanate had disappeared. In the following table are given the results of determinations by this procedure.

Polarographic Determination of Accelerators, Antioxidants, and Other Rubber Chemicals. I.

1959 ◽  
Vol 32 (4) ◽  
pp. 1254-1268
Author(s):  
F. Mocker
Keyword(s):  
Zinc Oxide ◽  
Quantitative Determination ◽  
Raw Materials ◽  
Zinc Stearate ◽  
Zinc Salt ◽  
Polarographic Method ◽  
Experimental Conditions ◽  
Methanolic Extracts ◽  
Rubber Compounds

Abstract The present paper shows that the Polarographic method for the determination of rubber additives (rubber chemicals) delivers fully usable results. The following points are discussed : 1. The method is qualified for a rapid quantitative determination of MBT and 2-mercaptobenzimidazole in raw materials control. 2. The zinc salt of MBT can be indirectly determined after its decomposition with acid. 3. MBT and 2-mercaptobenzimidazole can be determined directly in the methanolic extracts of masterbatches. 4. As with the masterbatches, MBT can be determined directly in the extracts of rubber stocks and vulcanizates when zinc oxide is absent. Magnesium oxide or zinc stearate do not interfere. 5. Experimental conditions are given which permit quantitative determinations of MBT in the presence of zinc oxide in uncured and cured rubber compounds. 6. The experiments have shown that the method is applicable to complex recipes containing MBT as the only accelerator. Of course, the limit of error is higher, that is, around −5%. The investigations are being continued and the results will be presented at a later date.

The Volumetric Determination of Free Sulfur in Rubber

1933 ◽  
Vol 6 (4) ◽  
pp. 518-519
Author(s):  
J. A. Robertson ◽  
J. Young
Keyword(s):  
Rapid Method ◽  
Acetone Extract ◽  
Review Of The Literature ◽  
Chemical Laboratory ◽  
Analytical Process ◽  
Time Control ◽  
Volumetric Determination ◽  
Control Work ◽  
Free Sulfur

Abstract The determination of free sulfur is probably the analytical process most frequently carried out in the chemical laboratory of a rubber factory, and it would be even more often used, could it be more quickly performed. For the oxidation of the sulfur contained in the acetone extract from rubber, Mackay (J. Soc. Chem. Ind., 49, 401-3T (1930)) has described a rapid method which has been used in these laboratories for several years with complete success, but the sulfate produced has to be determined gravimetrically and the process is still too slow for use in factory control work. The acetone extraction of the rubber samples can usually be carried out at night on a bath with automatic time control, and if a rapid method for the determination of sulfur in the extract were available, the results of the analysis could be ready early next day. From a review of the literature the volumetric determination of sulfate by rhodizonate (Strebinger and von Zombory, Z. anal. Chem., 79, 1 (1929)) appeared to be promising, and on trial has given satisfactory results.

Analysis of Vulcanized Rubbers. Influence of Accelerators on the Determination of Free Sulfur by the Copper Spiral Method

1952 ◽  
Vol 25 (4) ◽  
pp. 956-958
Author(s):  
J. Mann
Keyword(s):  
Hydrogen Sulfide ◽  
Copper Sulfide ◽  
Acetone Extract ◽  
British Standard ◽  
Standard Methods ◽  
Vulcanized Rubber ◽  
Potential Source ◽  
Source Of Error ◽  
Free Sulfur

Abstract The copper spiral method is being inserted in a revised edition of the “British Standard Methods of Testing Vulcanized Rubber”, and this raises the question of what sulfur compounds react as “free” sulfur. In this method, “free” sulfur is considered to be that part of the sulfur which is present in the acetone extract and which reacts with a copper spiral, placed in the acetone during the extraction, with the production of copper sulfide, the amount of which can be estimated after its removal from the acetone. Since most accelerators contain sulfur, it is obvious that the presence of accelerators or accelerator fragments is a potential source of error. Fourteen accelerators of various types were therefore examined, and it was found that some react with copper, producing compounds which evolve hydrogen sulfide on treatment with hydrochloric acid.

Sign in / Sign up

Export Citation Format

Share Document