Eosin solution preparation

Bromophenol blue 2, 7 -DichIorofluorescein Eosin, tetrabromofluorescein Fluorescein Potassium rhodizonate, C404(0K)2 Rhodamine 6G Sodium 3-aIizarinsuIfonate Thorin Dissolve 0.1 g of the acid in 200 mL 95% ethanol. Dissolve 0.1 g of the acid in 100 mL 70% ethanol. Use 1 mL for 100 mL of initial solution. See Dichlorofluorescein. Dissolve 0.4 g of the acid in 200 mL 70% ethanol. Use 10 drops. Prepare fresh as required by dissolving 15 mg in 5 mL of water. Use 10 drops for each titration. Dissolve 0.1 g in 200 mL 70% ethanol. Prepare a 0.2% aqueous solution. Use 5 drops per 120 mL endpoint volume. Prepare a 0.025% aqueous solution. Use 5 drops. 

If ferric hydroxide be prepared by the hydrolysis of ferric chloride the resulting colloid contains chlorine ions which can be replaced by more readily adsorbable picrate or eosinate ions leaving hydrochloric acid in solution. 

Several derivatives of Eosin have been prepared and employed to study biological systems. Their main applications are as singlet energy acceptors and as triplet probes [93-97] to measure the rotational mobility of virus particles [98] and proteins in membranes and in solution. Examples of proteins studied using Eosin derivatives include myosin [99,100], band 3 protein [101,102], pyruvate dehydrogenase [103,104], and Sarcoplasmic... 

The standard solutions of three organic dyes, rhodamine B, fluorescein, eosin Y and their mixtures were prepared with 2.5xl0 mol/l NaOH. The two-way EM/EX matrices of size... 

Preparation of Eosin (SECTION 641).—In a small flask cover 5 grams of fluorescein with 20 cc. of alcohol. Add slowly in small portions, taking 10 minutes for the operation, 4 cc. of bromine. Shake the flask frequently. When about one-half of the bromine has been added most of the fluorescein passes into solution as the dibrom-substitution-product as the addition continues the tetrabrom-substitution-produet crystallizes out. (Eq.) Allow the mixture to stand for an hour filter and... 

A number of derivatives of fluorescein are useful dyes. Uranin is the disodium salt of fluorescein. ChrysoUn is a salt of benzyl-fluorescein, which is formed from phthalic anhydride and benzyl-resorcinol. It dyes silk and wool a fast yellow, and is used in cotton dyeing. Eosin is the disodium salt of tetrabromo-fluorescein, which is prepared by the action of bromine on fluorescein. Its dilute alkaline solution is rose-colored, and exhibits an intense yellow-green fluorescence. Other dyes related to fluorescein are tetrabromo-dichlorofluorescein and various ethers of fluorescein and its substitution-products. The dyes of this class produce on silk and wool shades from yellow to reddish yellow, cherry-red, and purple. 

Prepare a 20 mM (—15 mg/ml) stock solution of eosine in DMF just prior to its use. Shield the container from light by wrapping it in aluminium foil. 

Another method for preparing the p-form is based on the reaction of lead nitrate and sodium azide, at room temperature and in the presence of organic dyes. When solutions of lead nitrate (20 %) and of sodium azide were run continuously into water at 20 °C only a-LA was observed, but if even as little as 0.02 % of eosin or other organic dye is present in the reaction mixture, the p-form appears. The crystals are best handled as single specimens as they are sensitive breaking one will set off the whole batch [16]. 

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