Bromophenol blue test

Amphoteric surfactants contain both anions and cations. They should show positive results when tested using either the basic methylene blue test for anionic surfactants or the alternative bromophenol blue test for cationic surfactants. 

Dissolve 0-3 g in about 75 ml of water in a separator and add 0-4 ml of bromophenol blue test solution (0-1 g of bromophenol blue dissolved in 3 ml of 0 05N sodium hydroxide and diluted to 200 ml with water), 10 ml of chloroform and 1 ml of N sodium hydroxide. Titrate with 0-02M sodium tetraphenylboron to the disappearance of the blue colour from the chloroform layer, adding the titrant dropwise towards the end of the titration and shaking vigorously after each addition. 1 ml 0 02M = 0-008962 g C27H42O2NCI. 

The completeness of the coupling step can be monitored using the bromophenol blue test. Please note that all traces of DIEA and TMP need to be removed by extensive washing to obtain a reliable result (reeNote 12). 

Bromophenol blue test is an alternative to the more toxic Kaiser test. A change from deep blue to yellow indicates disappearance of aminomethyl groups [27, 28]. 

A good technical grade of carbon tetrachloride contains not more than the following amounts of impurities 1 ppm acidity as HCl, 1 ppm carbon disulfide if manufactured by carbon disulfide chlorination, 20 ppm bromine, 200 ppm water, and 150 ppm chloroform. The residue should not exceed 10 ppm on total evaporation. The product should give no acid reaction with bromophenol blue, and the starch iodine test should indicate the absence of free chlorine. 

In this case the sulphonic acid group is present in a sulphon-phthalein dye namely the indicator bromophenol blue. As in the previous example, the species (R3NH + )(R S03 ) can be extracted into chloroform whilst the indicator itself is not extracted, and the colour of the extract is proportional to the quantity of surfactant in the material under test. 

Testing is undertaken by several methods, including chloroform extraction and use of a sulfonphthalein dye (absorbance of yellow-colored complex using bromophenol blue and bromocresol green) or the use of eosin (sodium tetrabromofluorescein) solution in acetone and tetrachloroethane solvent. After shaking with a citric acid buffer and eosin addition, upon standing the lower layer turns pink if filmer is present. Subsequent titration with Manoxol OT (sodium dioctyl sulfosuccinate) quantifies the filmer, with loss of the pink color indicating the end point. 

Modras (51) reported spot test reactions to differentiate hydralazine from closely related drugs. Reagents used were aqueous copper (I) chloride, aqueous ammonium molybdate, iodine in potassium iodide solution, aqueous cobalt (II) nitrate, alcoholic ninhydrin, and alcoholic bromophenol blue. The tests were performed on paper or on Silica Gel G. 

DMAC does not detect urea, but uronium ion (8). Another color test for urea nitrate, which is less specific but is simple and quick, was developed in Israel by A. Bomstein. It is based on the fact that urea nitrate is highly acidic thus, the pH indicator bromophenol blue changes its color from blue to yellow upon reaction with trace amounts of urea nitrate [95]. Red pigment formation in the reaction between p-DMAC and urea nitrate [91, 92] is as follows ... 

The current method (3, 4, 6, 22) involves steam distillation to separate the volatile (primarily acetic) acids from the non-volatile (fixed) acids. Special equipment has been devised for this separation (6). Sulfurous and sorbic acid content can be corrected, or the sulfurous acid may be removed (33). Carbon dioxide must be removed so that it does not interfere with the test (6, 33). An automated procedure is also available (34) which measures the volatile acids in the distillate at 450 nm using bromophenol blue. 

Transfer small amount of resin to the test tube, wash resin with DCM, and perform the bromophenol blue (BPB) test (29) for presence of free amine (see Note 6). 

Number 8 16 x 150 mm test tubes and place them in a test tube rack. Into each tube carefully pipette 0.10 ml of the bromophenol blue solution. 2-67. Into each of the tubes carefully pipette 12.0 ml of one of the buffer solutions prepared in steps 2-62 and 2-64. 

For the test, add 2-5 drops of a neutralised sample solution to 10 ml of bromophenol blue solution. Shake well and observe the colour of the mixture. If a blue colour is shown, the existence of a cationic surfactant is confirmed. 

The use of a low excess of the building block requires careful control of the progress of the acylation reaction. Besides the 3-hydroxy-4-oxo-3,4-dihydro-l,2,3-benzotriazine reagent 23, the incorporation of the building block can be monitored by addition of Bromophenol Blue (0.05% of the resin loading) [52,67,73] or Violet Acid 17 [20] to the reaction vessel, as well as the ninhydrin test [74]. If the coupling is carried out by in situ formation of the 1-hydroxybenzotriazole ester, an excess of 1-hydroxyben-zotriazole is required for reliable monitoring with Bromophenol Blue. 

Amodiaquine base is extracted from urine into amyl acetate immediately after alkalinization. The addition of bromophenol blue in S% boric acid to the organic phase causes a green to blue coloring, depending on the concentration of the drug. The sensitivity of the test is 0.8 mg%. 

Corn seedling NR has also been studied by mediated electrochemistry. MV was the artificial electron donor and the enzyme was dispersed in a Nafion film cast on a glassy carbon electrode. The electrode was tested with other mediators as well that had previously shown activity in a scaled-up electrochemical nitrate reducing bioreactor including azure A, safranin T, neutral red, bromophenol blue and cibacron blue. MV was the superior reductant and the biosensor was optimized with this mediator to show a low detection limit of 3.0 pM for the determination of nitrate in fertilizers and drinking-water samples. One of the main drawbacks of the biosensor was stability and activity was lost within two days. 

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