Congo red method

The I2-starch reaction is the basis of a spectrophotometric assay at 640 nm with amylose standards. A similar Congo red method is less precise than the iodine method, but it has the advantage of insensitivity to the DP, molecular size, and shape. The Congo red assay can therefore be supple-... 

ISO 182-1, Plastics Determination of the tendency of compounds and products ba.sed on inyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures Part 1 Congo red method, 1990. 

BS 2782 Method I.IOA. Determination of the thermal stability of polyvinyl chloride by the Congo red method. 1991. 

Abnormal aggregations of misfolded protein molecules stainable with the fluorescence Congo red method of Askanas [90], or more simply but less inclusively with crystal violet, are called "amyloid." The amyloid in skeletal mnsde tissue can be (a) extracellular, usually in mnsde connective tissue regions or in blood-vessel walls, including blood vessels of peripheral nerves or (b) intracellular (within muscle fibers) of s-IBM (see Chapters 7 and 10). Musde extracellular amyloid is often composed of the variable portion of an immunoglobulin light chain, or mutant transthyretin, but sometimes other proteins are involved primarily or secondarily. (Extracellular amyloid can be clinically identified, noninvasively, by Mibi radioisotope scanning [91]). We have previously postulated that cyto-disturbance... 

Figure 5.81 Influenoe of the buffer system on residual stability (Congo red method) in polyvinyl chloride films after UV irradiation with Xenotest 1200 (OSRAM Vitalux lamps), distance 30 cm, formulation 100 ml S-PVC, 54 ml DOP, I ml ESO, 3 ml Ba/Cd stabilizer [202]...

Stabilization 294 Composites 410 Composition 223, 233 Compostability 850 Compost test 878 Congo red method 497 Containers, oontainment 257... 

If the original ester is a fat or oil and produces an odour of acrolein when heated, it may be a glyceride. Esters of ethylene glycol and of glycol with simple fatty acids are viscous and of high b.p. They are hydrolysed (method I) and the ethyl alcohol distilled ofl. The residue is diluted (a soap may be formed) and acidified with hydrochloric acid (Congo red paper). The acid is filtered or... 

To hydrolyse an ester of a phenol (e.g., phenyl acetate), proceed as above but cool the alkaline reaction mixture and treat it with carbon dioxide until saturated (sohd carbon dioxide may also be used). Whether a solid phenol separates or not, remove it by extraction with ether. Acidify the aqueous bicarbonate solution with dilute sulphuric acid and isolate the acid as detailed for the ester of an alcohol. An alternative method, which is not so time-consuming, may be employed. Cool the alkaline reaction mixture in ice water, and add dilute sulphuric acid with stirring until the solution is acidic to Congo red paper and the acid, if aromatic or otherwise insoluble in the medium, commences to separate as a faint but permanent precipitate. Now add 5 per cent, sodium carbonate solution with vigorous stirring until the solution is alkaline to litmus paper and the precipitate redissolves completely. Remove the phenol by extraction with ether. Acidify the residual aqueous solution and investigate the organic acid as above. 

Prepare 26 g. of molecular sodium in a 1500 ml. round-bottomed flask (Section II,50,d, Method 1). Cover the sodium with 625 ml. of sodium-dried A.R. benzene fit the flask with an efficient reflux condenser protected from the air by means of a calcium chloride (or cotton wool) guard tube. Add 151 5 g. of diethyl adipate (Sections 111,99 and 111,100) in one lot, followed by 1 6 ml. of absolute ethyl alcohol. Warm the flask on a water bath until, after a few minutes, a vigorous reaction sets in and a cake of the sodio compound commences to separate. Keep the flask well shaken by hand during the whole of the initial reaction. After the spontaneous reaction has subsided, reflux the mixture on a water bath overnight, and then cool in ice. Decompose the product with ice and dilute hydrochloric acid (1 1) add the acid until Congo red paper is turned blue. Separate the benzene layer, and extract the aqueous layer with 100 ml. of benzene. Wash the combined extracts with 100 ml. of 5 per cent, sodium carbonate solution and 160 ml. of water dry over a KWe anhydrous magnesium sulphate. Remove the benzene under atmospheric pressure (Fig. II, 13, 4, but with modified Claisen flask), and fractionate the residue under reduced pressure. Collect the 2-carbethoxy-epelopentanone at 108-111°/15 mm. (96 g.). Upon redistillation, the product boils at 102°/H mm. 

Eisert R, Felau L, Brown LR (2006) Methods for enhancing the accuracy and reproducibility of Congo red and thioflavin T assays. Anal Biochem 353(1) 144-146... 

There have been many reports in which the immobilization method was covalent binding. In fact, many pH indicators used in above reports own at least one active amino or carboxyl group so that they can be covalently bound relatively easily to a solid substrate [165,166], Kostov et al. had discussed the immobilizing process of Congo red, neutral red and phenol... 

Many conventional OFCD exploit pH indicators as molecular probes.03-19 The pH indicators allow the detection of a chemical species by measuring the generation or uptake of hydrogen ions in chemical reactions. Some indicators such as p-nitrophenol,3) Congo Red,04 bromophenol blue,05 and others06-19 have been used successfully. Unfortunately, not all chemicals can be detected in this fashion and alternate methods of detection are necessary. Additionally, the use of absorbance spectroscopy by itself may not allow low detection limits since many molecules can interfere with absorbance measurements. 

The nitrous acid liberated at the anode reacts with the amine to form a diazonium compound, and this immediately condenses with the phenolic substance which is present to produce the azo-dye. Cooling is desirable though not so important as in the ordinary chemical method, since the diazonium compound couples with the phenol immediately it is formed but a diaphragm must be used to separate anode from cathode. Orange II, Congo red, dianisidine blue, and many other colours have been formed in this way. 

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