Bromcresol green

Bromcresol green, tetrabromo-m-cresol-sulfonphthalein (indicator) dissolve 0.1 g in 7.15 mL 0.02 N NaOH and dilute with water to 250 mL or, 0.1 g in 100 mL 20% alcohol pH range yellow 4.0-5.6 blue. 

Sodium bicarbonate is generally added to increase alkalinity and muriatic acid (HCl) or sodium bisulfate (NaHSO ) to reduce it. In general, with acidic sanitizers such as chlorine gas or trichloroisocyanuric acid, ideal total alkalinity should be in the 100—120 ppm range, whereas, with alkaline products such as calcium, lithium, or sodium hypochlorite, a lower ideal total alkalinity of 80—100 ppm is recommended (14). Alkalinity is deterrnined by titration with standard sulfuric acid using a mixed bromcresol green—methyl red indicator after dechlorination of the sample with thiosulfate. Dechlorination with thiosulfate causes higher readings due to formation of hydroxyl ion (32) ... 

In a titration of 50.00 mL of 1.00 M HC2H302 with 1.00 M NaOH, a student used bromcresol green as an indicator (A, = 1.0 X 10-5). About how many milliliters of NaOH would it take to reach the end point with this indicator Is there a better indicator that she could have used for this titration ... 

Of the indicators in Figure 18-6, one that has the pH of the equivalence point within its pH color change range is methyl red (yellow at pH = 6.2 and red at pH = 4.5) Bromcresol green would be another choice. At the 50 % titration point,... 

Paper chromatography has been used to separate and detect pseudoephedrine hydrochloride from other pharmacologically active amines. Whatman No. 1 paper developed in n-butanol water 95% acetic acid (4 5 1), n-butanol toluene water 95% acetic acid (10 10 5 5), ethyl acetate water 95% acetic acid (3 3 1), or chloroform water 95% acetic acid (10 5 4) gave Rf values of 0.73, 0.35, 0.57, and 0.52 for pseudoephedrine hydrochloride respectively. Visualization of pseudoephedrine hydrochloride was done by spraying the chromatogram with 0.5% bromcresol green in methanol or 0.2% nin-hydrin in acetic acid butanol 5 95.30... 

At the equivalence point, the point at which the moles of OH equals the moles of H30+, an indicator mixture of bromcresol green and methyl red with a suitable end point, was used to determine the equivalence point (pH of 5.1). The reason that the equivalence point is at 5.1 is that the ammonium ion present as a product hydrolyzes resulting in an acidic solution ... 

Methyl violet Cresol red Thymol blue Methyl orange Bromcresol green Methyl red Bromthymol blue Phenolphthalein Thymolphthalein Clayton yellow... 

After the flasks have cooled, swirl the solutions and add four or five drops of bromcresol green or methyl red indicator mix. If the solution is green, all the base has not been neutralized. In this case, add 25.00 mL of 0.2 M HC1 with a volumetric pipet and boil again for 10 min. Repeat this process until the solution remains red. 

Bromcresol green was used as the indicator for the Na2C03 titration in Experiment 11. Would phenolphthalein also work Explain. 

Would bromcresol green be an appropriate indicator for an acetic acid titration Explain. 

Why does the titration curve of sodium carbonate have two inflection points Why does this titration require that the solution be boiled as you approach the second equivalence point Why can bromcresol green be used as the indicator and not phenolphthalein ... 

Bromcresol green is frequently used for the quantitation of albumin, to which it binds selectively at pH 4.2 with a resulting increase in absorbance at 630 nm. The dye is initially a yellow colour but the resulting protein-dye complex is an intense blue colour (Figure 11.12). The method is relatively specific for albumin, bromcresol green being able to displace most substances that may be initially bound to the protein molecule. 

Figure 11.12 Absorption spectrum of the albumin-bromcresol green complex ...

Procedure 11.5 Quantitation of albumin using bromcresol green dye binding... 

The use of bromcresol green for the measurement of albumin has been criticized on several counts. There is a tendency for the protein-dye complexes to precipitate at pH 4.2, which is very near the iso-ionic pH of albumin. It is claimed that the method is not absolutely specific for albumin and particularly with serum samples shows a positive bias in results. There is also some variability in the intensity of the colour produced with albumins from different sources, a fact which makes the choice of the standard material important. 

Bromcresol purple has been suggested as showing improved specificity for albumin and less variation in colour intensity compared with bromcresol green. The dye-albumin complex shows an absorption maximum at 603 nm and the use of a reagent buffered at pH 5.2 appreciably reduces the tendency of the complex to precipitate. 

Chlorpromazine hydrochloride was assayed in neutral solvents such as acetone or acetonitrile with a glacial acetic acid solution of perchloric acid. The combination of methyl violet and bromcresol green served as a mixed indicator [57]. 

An ion-pairing spectrophotometric method has also been described [14]. This method involves the use of bromphenol blue, bromcresol purple, bromcresol green, bromthymol blue, or methyl orange, and extracting the ion-pair species into chloroform. The absorbance of the yellow product is determined at 420 nm. 

Bromcresol green, 0.1%, and methyl red, 0.01%, each in 96% ethanol mix in a volume ratio of 1 2. [A stronger methyl red stock solution (2) is difficult to prepare.] The working solution, which is stable indefinitely, is made by adding 12 ml of the mixed indicator per 100 ml of the boric acid. Only exceptionally need adjustment to the desired reddish-purple color be performed, by adding drops of acid or alkali. 

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