A Colorimetric Method for the Determination of Esters

1950 ◽  
Vol 3 (1) ◽  
pp. 128 ◽  
Author(s):  
AR Thompson
Keyword(s):  
Absorption Spectra ◽  
Colorimetric Method ◽  
Hydroxamic Acids ◽  
Degree Of Conversion ◽  
Maximum Absorption ◽  
Ferric Ion ◽  
Factors Influencing ◽  
Ferric Hydroxamate ◽  
Volatile Esters

The colorimetric method of Hill, based on conversion of esters to hydroxamic acids which form red complexes with ferric ion, has been adapted for the estimation of volatile esters. Investigation of the factors influencing the two reactions involved has led to a satisfactory procedure for esters derived from acids with an unbranched chain of two to ten carbon atoms and esters of isobutyric and isovaleric acids. The degree of conversion to ferric hydroxamate complexes has been found by reference to pure hydroxamic acids. The absorption spectra of the ferric hydroxamate complexes from all the esters examined show a maximum absorption at 520 mμ. Hence a mixture of esters may be estimated in terms of one of the esters.

A Simplification and Improvement in the Determination of Copper in Fabrics and Rubberized Materials

1932 ◽  
Vol 5 (3) ◽  
pp. 356-359
Author(s):  
F. Kirchhof
Keyword(s):  
Nitric Acid ◽  
Colorimetric Method ◽  
Test Solution ◽  
Ferric Ion ◽  
The Past ◽  
Equivalent Quantity ◽  
Determination Of Copper

Abstract The determination of small quantities of copper in fabrics and in rubberized materials can be simplified by destruction with concentrated nitric acid, which accelerates the ignition to the final ash. At the same time, this method avoids the usual danger of volatilization of copper as chloride as a result of the presence of chlorine from white factice or from cold vulcanization. Likewise, precipitation of the copper as sulfide can be avoided by repeating the precipitation of the extract from the ash, which contains predominantly aluminum and iron, with ammonia. In this second precipitation, only around 1 to 2 per cent of the total quantity of copper is retained in the precipitate and filter, and this quantity may in most cases be neglected. The ordinary colorimetric method used in the past for the detection of copper as complex cuprammonium ion can be made about ten times as sensitive by making use of the reaction: Cu+ + + 2I− → CuI + I. This is, however, applicable only in the complete absence of the ferric ion and of nitric acid in the test solution. The sensitivity can be increased still more by the addition of starch. Another advantage of the determination of copper by measurement of the equivalent quantity of iodine lies in the fact that, if necessary, only one-tenth as much sample need be used, but in this case as in all such determinations, the copper must be distributed uniformly throughout the material to be analyzed.

FACTORS INFLUENCING THE DETERMINATION OF MAXIMUM SURFACE TEMPERATURE FOR EXPLOSION-PROOF LUMINAIRES

2017 ◽  
Vol 16 (6) ◽  
pp. 1309-1316 ◽  
Author(s):  
Lucian Moldovan ◽  
Sorin Burian ◽  
Mihai Magyari ◽  
Marius Darie ◽  
Dragos Fotau
Keyword(s):  
Surface Temperature ◽  
Maximum Surface ◽  
Factors Influencing ◽  
Maximum Surface Temperature

Spectrophotometric study of the reactions of lanthanoids with bromopyrogallol red in the presence of cation active tensides

1982 ◽  
Vol 47 (2) ◽  
pp. 503-508 ◽  
Author(s):  
Irena Němcová ◽  
Pavla Plocková ◽  
Tran Hong Con
Keyword(s):  
Absorption Spectra ◽  
Photometric Determination ◽  
Spectrophotometric Study ◽  
Ternary Complexes ◽  
Optimal Conditions ◽  
Bromopyrogallol Red ◽  
Binary Complexes

The absorption spectra of the binary complexes of lanthanoids with bromopyrogallol red were measured and the formation of ternary complexes with cation active tenside, Septonex, was studied. Optimal conditions were found for the formation of these complexes and the possibility of their use in the photometric determination of lanthanoids was demonstrated on several examples.

The Need for Using An Enzymatic Colorimetric Assay in Creatinine Determination of Peritoneal Dialysis Solutions

1990 ◽  
Vol 10 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Liliane Larpent ◽  
Christian Verger
Keyword(s):  
Peritoneal Dialysis ◽  
Reliable Method ◽  
Colorimetric Assay ◽  
Colorimetric Method ◽  
Peritoneal Membrane ◽  
Creatinine Kinetics ◽  
Dialysis Solutions ◽  
Peritoneal Dialysis Solutions ◽  
Enzymatic Test

The fate of the peritoneal membrane on continuous ambulatory peritoneal dialysis (CAPD) is usually evaluated through the modification of its permeability to various solutes as glucose, creatinine, and urea. Therefore, the accuracy of the methods used for measurements of creatinine is of great importance. A particular problem does exist for creatinine determination as it may be influenced by the presence of glucose. We studied a new enzymatic colorimetric method for creatinine determination in peritoneal dialysis solutions which contain high dextrose concentrations. Creatinine was measured in plasma, urine, and dialysate from 18 patients on CAPD and in pure dextrose solutions, with an enzymatic test (Boehringer Mannheim) and with Jaffe's reaction on two different analyzers: Astra (Beckman) and Eris (Merck). Creatinine results were similar with both assays (Jaffe's reaction and enzymatic test) when measured in blood and urine. However the Jaffe's reaction gave higher creatinine results than the enzymatic test (p < 0.001), when assays were performed in peritoneal dialysis solutions and in pure glucose solutions. In addition, it appeared that other components of dialysis solutions, mainly calcium chloride, influenced unpredictably the results of creatinine with the Jaffe's reaction. We conclude that specific enzymatic test is a more accurate and reliable method to evaluate creatinine kinetics through the peritoneal membrane when determined in CAPD solutions.

Bestimmung der Dauerhaftigkeit von Hochleistungsbeton mit Hilfe des CDF-Tests / Determination of the durability of high performance concrete by means of CDF-test

1999 ◽  
Vol 5 (1) ◽  
pp. 29-40
Author(s):  
R. Krumbach ◽  
U. Schmelter ◽  
K. Seyfarth
Keyword(s):  
Frost Resistance ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Factors Influencing

Abstract Variable obsen>ations concerning frost resistance of high performance concrete have been made. The question arises which are the decisive factors influencing durability under the action of frost and de-icing salt. The proposed experiments are to be carried out in cooperation with F.A.- Finger - Institute of Bauhaus University Weimar. The aim of this study is to determine possible change of durability of high strength concrete, and to investigate the origin thereof. Measures to reduce the risk of reduced durability have to be found.

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