Determination of Copper in Rubber Latex

1951 ◽  
Vol 24 (2) ◽  
pp. 472-481
Author(s):  
F. C. J. Poulton ◽  
M. E. Tunnicliffe
Keyword(s):  
Aqueous Solution ◽  
Carbon Tetrachloride ◽  
Ferric Iron ◽  
Potassium Cyanide ◽  
Zinc Salt ◽  
Colorimetric Determination ◽  
Rubber Latex ◽  
Experimental Conditions ◽  
Carbon Tetrachloride Solution

Abstract Small amounts of copper in rubber latex can be determined by following a dry-ashing procedure for removal of organic matter and concluding with a colorimetric determination of the copper in the ash. Provided the ignition is not undubly prolonged, the ashing temperature can safely rise to 800° C, and recovery of the copper is complete from the ash when a mixture of nitric and hydrochloric acids is used. Results are slightly higher than those obtained by the wet oxidation process. Assay of the copper can be carried out on the solution of the ash, either in aqueous medium or in carbon tetrachloride solution, depending on the extent of interference anticipated from iron and insoluble ingredients, such as clay, and on the degree of accuracy required. Visual color matching in aqueous solution is simpler and quicker, but insoluble material may give rise to considerable personal error. In aqueous solution, the copper equivalent of ferric iron is about 1/100, i.e., the coloration is about 100 times more intense for copper than for iron. for more accurate work, measurement of the color of a carbon tetrachloride solution of the copper diethyldithiocarbamate complex by means of a suitable colorimeter is recommended. The tendency of the complex to fade is overcome by replacing the sodium diethyldithiocarbamate by the zinc salt dissolved in carbon tetrachloride. In such a solution the copper equivalent of ferric iron is about 1/1000, but actual experimental conditions can vary this figure between wide limits. A more satisfactory procedure is, therefore, to measure the total color developed in carbon tetrachloride, and then bleach out the color due to copper with potassium cyanide. The residual (interfering) colors can thus be estimated, and the difference between the readings gives a direct measure of the concentrations of copper in the test solution.

scholarly journals Nitroso-R-salt as a sensitive spectrophotometric reagent for the determination of paracetamol in pharmaceutical preparations

2009 ◽  
Vol 6 (3) ◽  
pp. 570-577
Author(s):  
Baghdad Science Journal
Keyword(s):  
Aqueous Solution ◽  
Statistical Difference ◽  
Pharmaceutical Preparations ◽  
Molar Absorptivity ◽  
Calibration Graph ◽  
Subsequent Reaction ◽  
Experimental Conditions ◽  
Colored Complex ◽  
British Pharmacopoeia

Nitroso-R-salt is proposed as a sensitive spectrophotometric reagent for the determination of paracetamol in aqueous solution. The method is based on the reaction of paracetamol with iron(III) and subsequent reaction with nitroso-R-salt to yield a green colored complex with maximum absorption at 720 nm. Optimization of the experimental conditions was described. The calibration graph was linear in the concentration range of 0.1 – 2.0 ?g mL-1 paracetamol with a molar absorptivity of 6.9 × 104 L mol-1 cm-1. The method was successfully applied to the determination of paracetamol in pharmaceutical preparations without any interference from common excipients. The method has been statistically evaluated with British Pharmacopoeia method and no statistical difference between methods was found at the 95% confidence level.

Colorimetric Determination of Oxyphenisatin and Oxyphenisatin Diacetate in Pharmaceutical Preparations

1964 ◽  
Vol 47 (4) ◽  
pp. 688-692
Author(s):  
Antoine Major
Keyword(s):  
Aqueous Solution ◽  
Organic Solvent ◽  
Silver Nitrate ◽  
Sodium Hydroxide ◽  
Column Chromatography ◽  
Sodium Hydroxide Solution ◽  
Pharmaceutical Preparations ◽  
Colorimetric Determination ◽  
Hydroxide Solution

Abstract A method is described which will quantitatively determine 0.1 mg oxyphenisatin or the diacetate in various pharmaceutical preparations. After removal of interferences by organic solvent extractions from aqueous solution and partition column chromatography, the reaction of oxyphenisatin (diacetate) with silver nitrate in alcoholic sodium hydroxide solution produces a violet solution, which follows Beer’s law (1—15 μg per ml). The method was satisfactorily applied to the assay of commercial tablets, liquids, and powders with recoveries, as per cent found of declared, in the range 95—101%.

Rapid Thin Layer Chromatographic Determination of Aflatoxin M1 in Powdered Milk

1985 ◽  
Vol 68 (5) ◽  
pp. 952-954
Author(s):  
Maria Luisa Serralheiro ◽  
Maria Lurdes Quinta
Keyword(s):  
Aqueous Solution ◽  
Carbon Tetrachloride ◽  
Thin Layer ◽  
Limit Of Detection ◽  
Chromatographic Determination ◽  
Methanol Solution ◽  
Aflatoxin M1 ◽  
Powdered Milk ◽  
Layer Chromatography

Abstract A method has been developed for the detection of aflatoxin Mi in milk. The toxin is extracted with chloroform, the extract is evaporated, and the residue is partitioned between carbon tetrachloride and an aqueous saline-methanol solution. The toxin is once again extracted with chloroform from the methanol solution and analyzed by thin layer chromatography. The limit of detection of Mi in powdered milk is 0.5 μg/ kg; recoveries of added Mj are about 83%. The limit of detection can be improved to 0.3 μg/kg if the plate is sprayed with an aqueous solution of H2S04 after development.

Pyridoxine Determined Fluorometrically as Pyridoxal Cyanide Compound

1964 ◽  
Vol 47 (5) ◽  
pp. 827-828
Author(s):  
Marilyn Macarthur Polansky ◽  
Ricpiard T Camarra ◽  
Edward W Toepfer
Keyword(s):  
Aqueous Solution ◽  
Manganese Dioxide ◽  
Potassium Cyanide ◽  
Fluorometric Determination

Abstract Pyridoxine was oxidized with manganese dioxide to pyridoxal, which was converted to pyridoxal cyanohydrin by a reaction with potassium cyanide. Fluorescence readings were linearly related over a range of 0.005 to 0.5 μg of pyridoxine/ml. Recoveries of pyridoxine as pyridoxal were good and offered a method for the fluorometric determination of pyridoxine in aqueous solution.

Rapid Determination of Furazolidone in Feed

1964 ◽  
Vol 47 (3) ◽  
pp. 562-565
Author(s):  
Loyal R Stone
Keyword(s):  
Carbon Tetrachloride ◽  
Rapid Determination ◽  
Official Method ◽  
Alumina Column ◽  
Additional Advantage ◽  
Carbon Tetrachloride Solution ◽  
Color Development ◽  
Laboratory Time

Abstract Furazolidone is extracted from feed into dimethylformamide-carbon tetrachloride solution and isolated by chromatography on an alumina column. After extraction into water the absorbance of furazolidone itself is measured without color development. The procedure requires much less laboratory time than method 33.025 and has the additional advantage of being specific for furazolidone. Accuracy is at least equal to that of the official method over the range 0.0055% to 0.033% furazolidone.

Small Amounts of Copper in Dyes and Rubber Chemicals. Colorimetric Determination with Zinc Dibenzyldithiocarbamate

1953 ◽  
Vol 26 (1) ◽  
pp. 257-262
Author(s):  
R. I. Martens ◽  
R. E. Githens
Keyword(s):  
Carbon Tetrachloride ◽  
Acid Solution ◽  
Specific Method ◽  
Colorimetric Determination ◽  
Acid Solutions ◽  
Metallic Ions ◽  
Reagent Solution ◽  
Cent Solution ◽  
Dyed Fabrics

Abstract This work was undertaken to provide a more specific method for the routine determination of small amounts of copper in rubber chemicals, dyes, and dyed fabrics. A dithiocarbamate type of reagent—a 0.01 per cent solution of zinc dibenzyldithiocarbamate in carbon tetrachloride—will selectively extract copper from acid solutions containing relatively large amounts of most other metals. The method is accurate and reproducible to about 0.5 microgram in the range of 0.5 to 40 micrograms of copper. No precipitations or filtrations are required. The reagent is commercially available, the reagent solution and the color of the extracted copper dibenzyldithiocarbamate are stable, and the acid solution remaining after extraction may be used to determine other metals. Because copper dibenzyldithiocarbamate is selectively extracted from solutions containing relatively large amounts of many other metallic ions, the reagent may be used to determine small amounts of copper in metals and their salts.

DETERMINATION OF GLYCEROL AND RELATED COMPOUNDS IN FERMENTATION SOLUTIONS BY PARTITION CHROMATOGRAPHY

1950 ◽  
Vol 28b (9) ◽  
pp. 535-540 ◽  
Author(s):  
A. C. Neish
Keyword(s):  
Aqueous Solution ◽  
Periodate Oxidation ◽  
Colorimetric Determination ◽  
Partition Chromatography ◽  
Sugar Alcohols ◽  
Modified Technique ◽  
Silica Column ◽  
To Receive ◽  
Related Compounds

A modified technique is described for applying partition chromatography, using a silica column, to the separation of simple organic compounds which are difficult to extract from water. An aqueous solution is pipetted directly on a Celite–water column the upper 15% of which has been left dry to receive it. Acetoin, 2, 3-butanediol, 1, 2-propanediol, ethanediol, glycerol, and erythritol can be separated from each other and from sugars and sugar alcohols containing five or more carbon atoms if the column is properly developed by ethyl acetate and benzene–butanol mixtures. After separation the compounds can be estimated by a rapid colorimetric determination of the acetaldehyde or formaldehyde formed by periodate oxidation. The recoveries are quantitative, thus making it possible to determine 1 to 2 mgm. of glycerol or 2, 3-butanediol within an error of ± 3% even when they are mixed with larger amounts of closely related compounds which cause interference in the usual methods.

Colorimetric Determination of Cyanide Liberated from Apricot Kernels

1977 ◽  
Vol 60 (4) ◽  
pp. 954-956 ◽  
Author(s):  
Keith L Egli
Keyword(s):  
Hydrogen Cyanide ◽  
Steam Distillation ◽  
Sodium Hydroxide Solution ◽  
Picric Acid ◽  
Colorimetric Method ◽  
Potassium Cyanide ◽  
Colorimetric Determination ◽  
Apricot Kernels ◽  
Aoac Method

Abstract A simple colorimetric method is described for determining the quantity of hydrogen cyanide produced by the spontaneous decomposition of amygdalin in apricot kernels. The evolved cyanide is collected in sodium hydroxide solution and assayed colorimetrically by reaction with picric acid. Results for duplicate assays, 3.02 and 3.06 mg CN-/g, compare well with those obtained by AOAC method 26.115 which specifies steam distillation and silver nitrate titration; results for triplicate assays were 3.02, 3.03, and 3.08 mg CN-/g by the latter. Recovery of cyanide from potassium cyanide at a level equivalent to 243 μg CN-/g was 101.0%.

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