Methyl red solution

Reagents. Methyl red solution. Dissolve 0.10 g pure crystalline methyl red in 30 mL 95 per cent ethanol and dilute to 50 mL with water. The solution required in the experiment (standard solution) is prepared by transferring 5.0 mL of the above stock solution to 50 mL of 95 per cent ethanol contained in a lOOmL graduated flask and diluting to lOOmL with water. 

A sample of silica, dried at 150°, representing about 10 m /gm, is added to 25 ml of a methyl red solution in benzene containing 0.6-0.7 gm of the azo compound per liter. After agitating for about 2 hours at room temperature, the concentrations of equilibrium solution and original solution are compared by spectrophotometry at 4750 A. The specific hydroxylated surface area in m /gm is calculated from the formula ... 

Bhatt et al. have described a method based on the complex formation between chlorpromazine and K3Fe(CN)5 [151]. The latter substance yielded a reduction wave at zero applied potential, and addition of chlorpromazine decreased the wave height in an amount directly proportional to the amount added. Optimum conditions for the determination were reported to be pH 7.4-6.2, use of 0.1 M KCl as the supporting electrolyte, and 0.001% methyl red solution as the maximum suppressor. In this system, chlorpromazine can be determined up to concentrations of 1.4 pg/mL. 

Another official procedure (30) involves digestion of an accurately weighed sample of saccharin in hydrochloric acid. The resulting ammonium salt is reacted with sodium hydroxide and the liberated ammonia is distilled into 0.1 N sulphuric acid. The excess of the acid is determined by titrating with sodium hydroxide using methyl red solution as indicator. 

Mixed Indicator Solution Prepare separate 0.1% solutions of bromocresol green in methanol and the sodium salt of methyl red in water. Mix 5 parts by volume of the bromocresol green solution with one part of the methyl red solution. 

Lanthanum perchlorate, anthranilic acid and methyl red solutions of /i = 0.2 M are placed in the temperature jump cell and equilibrated. Since AH is small, the indicator change of the system is also small. The wavelength region 470-525 nm was chosen for the temperature jump. 

Methyl Red Solution. Dissolve 24 mg of methyl red sodium in purified water to make 100 ml. If necessary, neutralize the solution with 0.02 A-sodium hydroxide... 

For the test, the contents of the autoclaved containers are combined into a conical flask. The same volume of purified wafer is placed into a second similar flask as a blank. Add to each flask 0.05 ml of methyl red solution for each 25 ml of liquid. Then titrate the blank with 0.01 M hydrochloric acid and the test liquid until the color of the testing solution is the same as that obtained for the blank. Subtract the value found for the blank titration from that found for the test liquid, and express the results in milliliters of 0.01 M hydrochloric acid per 100 ml. The results, or the average of the results if more than one titration is performed, are not greater than the values stated in Table 4. 

The method of assay depends on the extraction and purification of the total alkaloids by solvent extraction technique. The residue of total alkaloids is then dissolved in several ml of chloroform, 20 ml of 0.01M sulfuric acid VS is added and the chloroform is removed by evaporation on a water-bath. The excess acid is titrated with 0.02M sodium hydroxide VS using methyl red solution as indicator. 

G. PicHARD and R. Chaminade have studied the behavior of methyl red and various sulfonephthaleins when shaken with organic solvents. They added ten drops of a 0.1% methyl red solution or of a 0.04% solution of a sulfonephthalein to 10 c.c. of aqueous solutions at different pH s, and noted the color of isobutyl alcohol extracts. They made the following observations with isobutyl alcohol as solvent ... 

The hydrolysis.error becomes smaller for smaller c and larger Km values. It is very small for neutralized methyl red solutions, but much greater for neutralized solutions of bromthymol blue. Evidently one obtains a correct measure of the reaction of pure water with neither the pure indicator solution nor with the neutralized solution. 

Results of measurements of the pH of slightly hydrolyzed zinc sulfate solutions are contained in the accompan3dng table. The determinations were made both with the hydrogen electrode and with isohydric methyl red solutions. ... 

Capillary phenomena may arise from other causes. Thus a solution of ammonium acetate turns both red and blue litmus papers violet. The drops are more bluish in the center and more red at the edge. It appears that the paper hinders the diffusion of ammonium hydroxide to a greater extent than it does the diffusion of acetic acid. The effect is even more evident when the reaction is produced with lead acetate. Around the center of the drop is found a blue region (adsorption of lead hydroxide) which is surrounded by a red region due to the diffusion of the acetic acid. These observations account for the discrepancy found in medical books regarding the reaction of lead acetate. It is impossible to determine accurately the reaction of this salt with litmus paper. It can be done, however, with methyl red solutions. The reaction resulting from the hydrolysis of salts such as sodium acetate and ammonium chloride is demonstrated readily by means of indicator papers. 

Preliminary preparation. Place 25 ml of the periodate reagent in the distillation flask, add 10 ml of water, and stir well. Add a few fragments of porous porcelain and distil 10 ml of water into a receiver containing 5 ml of the Methyl Red solution. Transfer the solution from the receiver to a 25-ml standard flask, make up to the mark with water, and measure the absorbance of the solution against water. The absorbanee measured should not be lower than the absorbance of the solution obtained by diluting 5 ml of the Methyl Red solution with water in a 25-ml standard flask. If the absorbance is lower, add 10 ml of water to the distillation flask, and repeat the procedure described above. 

Complete discoloration of the Methyl Red solution implies that too large a sample was taken. 

When free chlorine is determined in tap water, a sample of water is placed in a still (with no oxidizer) and chlorine is distilled, along with some water, into a reeeiver containing Methyl Red. The sample water may also be added directly to a Methyl Red solution. 

Procedure in teBt—1. To 5 cc. of each culture add 6 drops of methyl red solution. 

Solutions of strong mineral acids (HjSO, HCl, HNO3) change the yellow colour of neutral methyl red solution to a pink colour. The colour intensity is proportional to the concentration of hydrogen ions of mineral acids in... 

Treat the distillate with five drops of methyl red solution and titrate with 0.025 m H2SOz from yellow to red. Boil up the solution briefly so as to expel CO2, cool off to room temperature and titrate again to the same colour. 

As well as the p-hydroxybenzoate esters, sorbic and benzoic acids are also often used in food technology as preservatives. According to Copitjs-Peereboom [20], these preservatives may be satisfactorily separated on cellulose layers (Firm 83) using n-butanol-35% ammonium hydroxide-water (70 + 20 + 10) at chamber saturation. Visualisation is performed with a bromophenol blue-methyl red solution (Rgt. No. 29), followed by spraying with permanganate solution. 

Indicator Brom cresol green-methyl red solution prepared by mixing 5 parts BCG solution and 1 part MR solution, each made by dissolving 0.1 g of the indicator in 100 ml of ethanol. 

Transfer a 25 ml aliquot of the standard ammonium chloride solution (1 ml = 10 pg N) into the distillation tube of the nitrogen apparatus and 10 ml boric acid solution (1 %) and 2 drops methyl purple (bromo-cresol green/methyl red) solution (0.1 %) into the receiving flask the tip of the outlet should be just above the solution in the receiving flask. 

Step 7. Add 5 ml of 4 (NHij)2 2 4 <3rops of methyl red Indicator solution, and make basic by the dropwlse addition of cone. NHj OH. Hake the solution Just red to the Indicator by the dropwlse addition of 6h HNO, and add 3 drops In excess. Plate at 1.1 ang> and 6 volts for 1 hr at 80 C. At the end of the first 10 min, add 3 drops of methyl red solution and make acid with 6M HNO. Check acidity at two additional 10-min Intervals, and at the end of 40 min add 3 drops of cone. NH OH. At 10-mln intervals thereafter check to see that the plating solution Is Just basic to the Indicator. Remove the cell from the water bath, wash three times with methanol. 

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