Phenol red indicator

The pH is measured colorimetricaHy with phenol red indicator. High FAC causes lower pH rea dings due to bleaching of the indicator and resultant HCl formation. The pH of pool water is readily controlled with inexpensive chemicals. Hydrochloric acid solution or sodium bisulfate lower it, whereas sodium carbonate raises it. Since acid addition neutralizes a portion of the alkalinity, this must be replenished if the alkalinity drops below the minimum. By contrast, pH adjustment with carbon dioxide does not affect alkalinity. 

Gravimetric and volumetric methods are practicable for the quantitative determination of the a-sulfo fatty acid esters. Using gravimetric methods the surfactant is precipitated with p-toluidine or barium chloride [105]. The volumetric determination method is two-phase titration. In this technique different titrants and indicators are used. For the analysis of a-sulfo fatty acid esters the quaternary ammonium surfactant hyamine 1622 (p,f-octylphenoxyethyldimethyl-ammonium chloride) is used as the titrant [106]. The indicator depends on the pH value of the titration solution. Titration with a phenol red indicator is carried out at a pH of 9, methylene blue is used in acid medium [106], and a mixed indicator of a cationic (dimidium bromide) and an anionic (disulfine blue VN150) dye can be used in an acid and basic medium [105]. 

M HCI NaHC03 100-mL beaker 10-mL graduated cylinder dropper phenol red indicator... 

Add 2-3 drops of phenol red indicator. The solution should be red in color. Place a piece of white paper under the beaker to view the color of the solution better. 

The bioreactor is allowed to become established without interference for about 4 d or until the pH of the medium begins to fall (color change of the phenol red indicator), whichever is sooner. This time limit is critical, because glutamine levels fall rapidly and the antibiotic cover deteriorates. 

A 50-mL sample aliquot is treated with 2 mL buffer solution followed by 2 mL phenol red indicator and 0.5 mL chloramine-T solution. Shake well after... 

P 34] Dilution-type dye imaging with phenol red indicator and dilute hydrochloric acid solution was applied and monitored by video taping [34], Details on flow rates were not given. 

Kenny (1973) recommends a Soy peptone-yeast dialysate medium (Appendix 4) for culture of mycoplasma. Inclusion of arginine (16 mM) and 0.4 mg% phenol red indicates the presence of arginine deaminase by formation of alkali (purple coloration). Alternatively, incubation with tritiated thymidine and analysis of the culture medium for tritiated thymine can be used to detect thymidine phosphorylase (House and Waddell, 1967). 

Inclusion of arginine (16 mM) and 0.4 mg% phenol red indicates the presence of arginine deiminase by formation of alkali (purple colouration). 

Do not put a pH probe into the HBSS mixtures to be used for eosinophil purification and labeling. Adjust the pH of HBSS/BSA and HBSS/citrated plasma by adding 0.1 MNaOH until the color of the phenol red indicator in the HBSS shows pH 7.3. (Remove an aliquot to check the pH and then discard.) Adjust the pH of Percoll/HBSS by cautious addition of 1M HC1 with mixing to prevent formation of a precipitate. Use the color of the phenol red indicator as a guide, but only remove a small aliquot for pH measurement if the pH probe will function with 100 pL or less (and then discard). 

These acid- or alkaline-balanced products may be advertised as pH balanced. But what does pH mean We can get a clue from revisiting the pool test kit. The phenol red indicator is also labeled pH indicator pH is a measure of how acidic or basic a solution is. It is a measure of the acid quality of a solution. 

M HCl solution by titrating 5.00 mL of it with the standard 0.1 MNaOH as in Experiment 7. The phenol red indicator may be used. If you have only a standard 0.1 M HCl solution, use this to standardize 0.1 M NaOH solution. 

Preparation of comparison solution. Prepare a standard for color comparison at the end point as follows. Place 6 mL of 1% saline solution in a 25-mL Erlenmeyer flask and add 0.10 mL semm or plasma. Add two drops phenol red indicator, insert a stopper, and rotate gently to mix the contents. The transition range of this indicator is pH 8.4 to 6.7 (yellow to red). Because of the buffering capacity of the blood, the end point occurs in this range. 

Ammonia in whole blood and plasma is determined by adding sodium hydroxide to the sample and releasing the ammonia into an acceptor stream containing phenol red indicator [24] (cf. Sec. 9.2.4). 

Hydroxyester Synthesis MD I>2qM silicone polymer was dispersed in an equal weight of toluene. 0.1 wt % trlethylamlne was added, and varying amounts of benzoic acid or acetic acid were added, followed by reflux until titration with phenol red indicator showed that >95% of the carboxylic acid had been consumed. Toluene, trlethylamlne, and unreacted carboxylic acid were removed via vacuum strip to 150 C. Selected properties of polymer products are found in Table II. 

One milliliter of purified virus containing 200 pg of virus was acidified by the addition of 2 mL of 0.1M NaH2P04. Phenol red indicator solution was added (0.05 mL), and the mixture was left at room temperature for 10 min, after which the pH was adjusted to 7.4 by the addition of 0.1 MNaOH. 

Srour, R. K. and McDonald, L. M. Determination of the acidity constants of methyl red and phenol red indicators in binary methanol- and ethanol-water mixtures. J. Chem. Eng. Data, 53, 116-127 (2008). 

Adjust the penicillinase to pH 7 5 using phenol red as indicator. Prepare a colour control by mixing 1 ml of this with 10 ml of distilled water containing 0 2 ml of phenol red indicator. Weigh accurately 50 mg of the penicillin sample, dissolve in 10 ml of water also containing 0-2 ml of phenol red indicator, and adjust the pH value to match that of the control. Add 1 ml of penicillinase and allow to stand at room temperature for thirty minutes. Titrate with 0-01N sodium hydroxide until the colour of the solution again matches that of the control. Allow to stand for some minutes longer to ensure that the reaction is completed, and titrate further if necessary. Calculate the potency of the preparation on the basis that 1 ml of O OIK sodium hydroxide is equivalent to 6023 I.U. of p( nicillin. 

Weigh 0-3 g into a flask, add 120 ml of water and boil gently until dissolved. Cool, add 20 ml of O IN silver nitrate and 1-5 ml of phenol red indicator and titrate the liberated nitric acid with 0-lN sodium hydroxide to a deep red-violet colour. 1 ml 0-1N — 0-01802 g C7H8O2N4. 

Starting with about 10 mL of dilute NaCI(aq) containing a couple of drops of phenol red indicator, what color would the solution be for each of the following actions (a) first 10 drops of 1.0 M HCI(aq) are added to the solution (b) next 15 drops of 1.0 M NaCH3COO(aq) are added to solution (a) ... 

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