Thymol blue test

The Japanese scientists tested the fiber optic carbon dioxide sensor86, prepared by dip-coating method - the sol-gel film containing indicator dye, thymol blue, was deposited on unclad fiber. The sensitive film had both organic and inorganic parts with good permeability. The differences between attenuation in N2 gas and in CO2/N2 mixture gas increased with the CO2... 

Acidity Transfer about 25 g of sample, accurately weighed, into a 125-mL conical flask add 50 mL of toluene and 2 drops of thymol blue TS and titrate rapidly with 0.02 M sodium methoxide in toluene. Swirl the flask continuously until the yellow color changes to a dark color, and then continue the titration without stopping but slowing the addition of titrant until a single drop changes the solution to a clear blue color. The endpoint is stable for about 8 to 15 s. Not more than 1.0 mL of 0.02 M sodium methoxide is required. Lead Determine as directed for Method I in the Atomic Absorption Spectrophotometric Graphite Furnace Method under Lead Limit Test, Appendix IIIB. 

Hydroxylamine Hydrochloride Solution Dissolve 20 g of hydroxylamine hydrochloride in sufficient water to make about 65 mL, transfer the solution into a separator, add a few drops of thymol blue TS, then add ammonium hydroxide until the solution assumes a yellow color. Add 10 mL of a 1 25 solution of sodium diethyldithiocarbamate, mix, and allow to stand for 5 min. Extract the solution with successive 10- to 15-mL portions of chloroform until a 5-mL test portion of the chloroform extract does not assume a yellow color when shaken with cupric sulfate TS. Add 2.7 N hydrochloric acid until the extracted solution is pink, adding 1 or 2 drops more of thymol blue TS if necessary, then dilute to 100 mL with water, and mix. 

Deri here (Ref 3) modified these methods by adding the water, used for washing the gases evolved during the stabilization test, directly to the container in which the proplnt had been heated and determining the pH colorimetrically (instead of electrometrically) by a series of sensitive indicators (thymol blue for pH 2 to 3 3 btomophenol blue 2.8 to 4.6, bromocresol green 3.6 to 4.8 methyl orange 3.S to 5 2 bromocresol purple 5-2 to 6,8 and bromothymol blue 6.0 to 7.6)... 

For the test, add 5 ml neutralised sample solution to 5 ml thymol blue solution. Shake well and observe the colour of the mixture. A reddish-purple colour is the evidence of existence of anionic surfactants in the sample solution. 

To an aliquot of solution containing not more than 50 /ig of copper in a volume of not more than 25 ml add 2 g of citric acid and 0 5 g of the disodium salt of EDTA. Add 10 per cent solution of ammonia until the pH is approximately 9 (thymol blue). Add 10 ml of a freshly prepared 0 1 per cent solution of sodium diethyldithiocarbamate and extract immediately with three portions, each of 5 ml, of carbon tetrachloride added from a burette, passing each extract through a small filter of cotton wool. A blank should be run with reagents at the same time. Measure the extinction of the mixed extracts at 435 m u and obtain the number of micrograms of copper equivalent to the observed extinctions of the test and blank solutions from a calibration graph prepared as follows ... 

Measure carefully by pipette 10 ml. of gastric contents into a flask or large test tube. Add 5 drops of O-l per cent, thymol blue or t.p. indicator. A red colour denotes the presence of free hydrochloric acid. 

In the known absence of bromoform, iodoform, chloral, and other halogenated methanes, the formation of phenyhsonitrile with aniline provides a simple and faidy sensitive but nonspecific test for the presence of chloroform, the carbylamine test. Phenyhsonitrile formation is the identification test given in the British Pharmacopoeia. A small quantity of resorcinol and caustic soda solution (10% concentration) added to chloroform results in the appearance of a yellowish red color, fluorescing yeUow-green. When 0.5 mL of a 5% thymol solution is boiled with a drop of chloroform and a small quantity of potassium hydroxide solution, a yellow color with a reddish sheen develops the addition of sulfuric acid causes a change to brilliant violet, which, diluted with water, finally changes to blue (33). 

All this can mean that, if the aq soln of unknown sample is colorless in Test 2, no ppt with,Nessler s reagent, no color with ethylene-diamine in Test 2, deep blue color with DPhA in Test 3 and green a>lor with thymol soln in Test 4, it could be NG... 

B. Identification. Place ca 0.2g of material in a 5 ml beaker, add 2-3 ml distd w and stir for 5 min. Decant the liq through a filter into a small beaker, Evap this to dryness and test part of the deposit white, in the case of BkPdr) with 1 drop of 1% DPhA soln in coned H2S04, using a white porcelain spot-test plate A blue color indicates the presence of a nitrate. Place another portion of the deposit in an indenture of a white porcelain spot-test plate, add an equal amt of cryst thymol and... 

The EO of Ziziphora clinopodioid.es ssp. rigida (blue mint bush) was isolated by hydrodistillation of the dried aerial parts, which was collected during the anthesis. The main compounds are thymol and 1,8-cineole with a content of 8% and 2.7%, respectively. Different extracts were tested by the DPPH assay to determine the antioxidative activity and showed that the free radical scavenging activity of the menthol extract was superior to all other extracts. Polar extracts exhibited stronger antioxidant activity than nonpolar extracts (Salehi et al., 2005). 

RDX. Place several milligrams of the white, unknown material in a test tube and add about 200 milligrams of thymol and six drops (0.3 ml) of concentrated sulfuric acid. Warm the tube for five minutes at 100°C, and add 5 to 10 milliliters of ethanol. RDX produces a rich blue color. Under these conditions sugars and aldehydes give a brown color, and HMX... 

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