Identification of Curing Agents in Rubber Products. Ultraviolet Absorptiometric Analysis of Selective Solvent Extracts

1956 ◽  
Vol 29 (1) ◽  
pp. 319-332 ◽  
Author(s):  
K. E. Kress ◽  
F. G. Stevens Mees
Keyword(s):  
Quality Control ◽  
Aqueous Solutions ◽  
Organic Compounds ◽  
Ethyl Ether ◽  
Test Methods ◽  
Spot Test ◽  
Selective Solvent ◽  
Elapsed Time ◽  
Quantitative Results ◽  
Curing Agents

Abstract A method has been devised for identification of organic compounds that accelerate the vulcanization of rubber products. Identification of these active trace materials aids product improvement and quality control. Identification is made through ultraviolet spectrophotometric absorbance curves over the 220 to 380 mµ region on the aqueous alkali or acid extracts, or on liquid-liquid ethyl ether extracts of the aqueous solutions. Thiazole, thiuram, thiocarbamate, amine, and guanidine classes of commercial accelerators are regularly identified in 2 grams of uncured or cured rubber products, with less than 4 hours' elapsed time. Interference of common softeners and antioxidants is usually negligible. The method is more rapid than chromatographic procedures and more sensitive and specific than spot-test methods. Quantitative results may be obtained if calibration work is undertaken.

Estimation of the effect of NaCl on the solubility of organic compounds in aqueous solutions

2000 ◽  
Vol 89 (12) ◽  
pp. 1620-1625 ◽  
Author(s):  
Nina Ni ◽  
Mohamed M. El‐Sayed ◽  
Tapan Sanghvi ◽  
Samuel H. Yalkowsky
Keyword(s):  
Aqueous Solutions ◽  
Organic Compounds

Animal Models and Alternatives in the Quality Control of Vaccines: Are In Vitro Methods or In Vivo Methods the Scientific Equivalent of the Emperor's New Clothes?

1995 ◽  
Vol 23 (1) ◽  
pp. 61-73
Author(s):  
Coenraad Hendriksen ◽  
Johan van der Gun
Keyword(s):  
Quality Control ◽  
Test Methods ◽  
In Vitro Test ◽  
Large Numbers ◽  
Alternative Approach ◽  
Inactivated Vaccines ◽  
Vitro Test

In the quality control of vaccine batches, the potency testing of inactivated vaccines is one of the areas requiring very large numbers of animals, which usually suffer significant distress as a result of the experimental procedures employed. This article deals with the potency testing of diphtheria and tetanus toxoids, two vaccines which are used extensively throughout the world. The relevance of the potency test prescribed by the European Pharmacopoeia monographs is questioned. The validity of the potency test as a model for the human response, the ability of the test to be standardised, and the relevance of the test in relation to the quality of the product are discussed. It is concluded that the potency test has only limited predictive value for the antitoxin responses to be expected in recipients of these toxoids. An alternative approach for estimating the potency of toxoid batches is discussed, in which a distinction is made between estimation of the immunogenic potency of the first few batches obtained from a seed lot and monitoring the consistency of the quality of subsequent batches. The use of animals is limited to the first few batches. Monitoring the consistency of the quality of subsequent batches is based on in vitro test methods. Factors which hamper the introduction and acceptance of the alternative approach are considered. Finally, proposals are made for replacement, reduction and/or refinement (the Three Rs) in the use of animals in the routine potency testing of toxoids.

PROGRESS IN THE ANALYSIS OF INORGANIC AND ORGANIC COMPOUNDS IN NON-AQUEOUS SOLUTIONS

1962 ◽  
Vol 31 (4) ◽  
pp. 244-266 ◽  
Author(s):  
A P Kreshkov ◽  
L N Bykova ◽  
N A Kazaryan ◽  
N Sh Aldarova
Keyword(s):  
Aqueous Solutions ◽  
Organic Compounds ◽  
Inorganic And Organic

Some applications of polarography for investigation of equlibria in aqueous solutions of organic compounds

2009 ◽  
Vol 74 (11-12) ◽  
pp. 1777-1789 ◽  
Author(s):  
Petr Zuman
Keyword(s):  
Aqueous Solutions ◽  
Organic Compounds ◽  
Carbonyl Compounds ◽  
Limiting Current ◽  
Nitroso Compounds ◽  
Primary Amines ◽  
Acid Base ◽  
Fast Reactions ◽  
Half Wave

There are two possibilities how to follow equilibria of organic compounds established in aqueous solutions using polarography: for very fast reactions, information can be obtained from shifts of half-wave potentials. For slowly established equilibria, the changes in the limiting current are followed. In both cases variation of the half-wave potentials or limiting currents with concentration of a reactant, present in excess, is followed. The types of reactions, which had been followed in this way, are as follows: hydration–dehydration equilibria, additions of hydroxide ion to carbonyl and nitroso compounds, the role of slowly established acid–base equilibria involving C-acids; further also reactions involving the addition of ammonia, primary amines, hydroxylamine, and hydrazine to carbonyl compounds.

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