Alizarin complexan

Fluoride Indicator solution Prepare a solution containing 100 mg of lanfhanum-alizarin complexan mixfure per milliliter in 60% isopropyl alcohol. Filter the solution if it is not clear. 

Prepare a buffered alizarin cornplcxan solution by weighing 40.1 mg of 3-aminomethylalizarin-A,A-diacetic acid into a beaker and add 1 drop of 1 N NaOH followed by 20 ml of distilled water. Warm to dissolve, then cool and dilute to 200 ml. Prepare a separate solution of 4.4 g of sodium acetate in water. Add 4.2 ml of glacial acetic acid and dilute to 42 ml. Pour this sodium acetate solution into the alizarin complexan and mix to form the buffered solution. 

Abbreviation as in Table 6 with BPR = bromopyrogallol red RBE = rose bengal extra, tetrachloiotetraiodofluorescein MTB = methylthymol blue salf = salieylfluorenone DHC = dihydroxychromenol Hsal = salicylic acid ALC = alizarin complexan. 

The condensation product of dihydroxyanthraquinone with formaldehyde and iminodiacetic acid was introduced by Belcher, Leonard and West (1958) under the name alizarin complexan (58), though the names alizarin complexone or (nowadays) alizarin fluorine blue are preferred. It greatly resembles xylenol orange in its general behaviour though its complexes with thorium and the lanthanons are more stable than these EDTA complexes. However, the most interesting... 

Ternary complex formation with alizarin complexan -Ce lll) Color changes from red to lilac blue None 0.2... 

A method for the determination of fluorine in fluorinated polymers such as polytetrafluoroethylene (PTFE) is based on decomposition of the sample by oxygen flask combustion followed by spectrophotometric determination of the fluoride produced by a procedure involving the reaction of the cerium(III) complex of alizarin complexan (1,2-dihydroxy-anthraquinone-3-ylmethylamine N,N-diacetic acid). The blue colour of the fluoride-containing complex (maximum absorption, 565 nm) is completely distinguishable from either the yellow of the free dye (maximum absorption, 423 nm) or the red of its cerium(III) chelate (maximum absorption, 495 nm). 

Test with cerium i-- or lanthanum-alizarin complexan ... 

Fluoride ions change the red color of the chelate of alizarin complexan (l,2-dihydroxyanthraquinone-3-methylamino-N,N-diacetic acid) with trivalent cerium to lilac blue, the color of the alizarin complexan itself. The behavior of lanthanum-alizarin complexan is analogous. ... 

Procedure. One drop of the test solution is mixed in a micro test tube with a drop of 0.001 M alizarin complexan buffered to pH 4.3 with sodium acetate-acetic acid. One drop of 0.001 M cerium nitrate is added with stirring. A lilac to blue color indicates the presence of fluorine. 

When a 0.001 M lanthanum nitrate solution is used, the alizarin complexan solution is buffered to pH 5.4. 

Alizarin complexan, 0.0005 M, transfer 0.385 g of alizarin complexan to a 2 litre calibrated flask by means of 20 ml of recently prepared 0.5 N sodium hydroxide and set aside for 5 minutes with occasional swirling, to ensure complete solution. Dilute to about 1500 ml with water, add 0.2 g of hydrated sodium acetate and adjust the pH to about 5 by careful addition of 1 N hydrochloric acid. Dilute to the mark and filter into a brown glass bottle. Tbis solution is stable for at least 4 months. 

In each of a series of 100 ml calibrated flasks place 50 ml of distilled water, an accurately measured volume between 2 and 8 ml of standard fluoride solution, 10 ml of alizarin complexan solution and 3 ml of acetate buffer solution. Mix each solution thoroughly, add 10 ml of 0.0005 M cerous nitrate, dilute to the mark with distilled water and set aside, protected from direct light for 1 hour. At the same time, prepare a blank solution in a similar fashion by omitting the standard fluoride solution. Measure the optical densities of the test solutions against the blank in 4 cm cells at 610 nm and plot a graph of optical density against amount of fluoride present. 

Transfer 20 ml of distilled water and 2.4 ml of buffered alizarin complexan solution to a 50 ml beaker. Add 1 ml of test solution and mix swirling the solution. Finally, add 2 ml of cerous nitrate solution and mix again. Treat the blank solution in a similar manner. When fluorine is present in the sample a mauve colour will be developed in the test solution (compared with the pink coloured blank solution). If a semi-quantitative estimation of fluorine is required, set the solutions aside for 10 minutes and measure the optical density of the test solution against the blank solution at 600 nm in 1 cm cells. Sulfur, chlorine, phosphorus and nitrogen do not interfere in this procedure. 

Transfer the distillate to a 250-ml separator and add 10 00 ml of alizarin complexan solution and 2 00 ml of buffer solution, pH 4 3. Mix and immerse the separator almost completely in a water-bath, maintained at 25 2", for ten minutes, swirling periodically. Then add... 

Application of the oxygen-flask combustion method to the determination of fluorine in organic combination has now been made by a number of workers. The fluoride in solution after combustion may be determined by thorium nitrate titration or colorimetrically as the alizarin complexan chelate or with a chloranilate (see Halogen Acids and Salts, p. 302). A method based upon the alizarin complexan chelate is given in Appendix IV. 

Li J, Yi F, Shen D, Fei J (2002) Adsorptive stripping voltammetric study of scandium-alizarin complexan complex at a carbon paste electrode. Anal Lett 35 1361-1372... 

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