Xylidyl Blue

Magon [3-hydroxy-4-(hydroxyphenylazo)-2-naphthoyI-2,4-dimethyIanilide Xylidyl Blue... 

Eriochrome black T, oxine,b xylidyl blue, HQBA,b quinalizarin ... 

Hydroxyquinoline 8-Hydroxyquinoline + Butylamine Titan Yellow Xylidyl Blue Formaldoxime... 

Magon [3-hydroxy-4-(hydFoxyphenylazo)-2-naphthoyl-2,4-dimethylaiii]ide, Xylidyl Blue H [523-67-1] M 411.5, m 246-247 . Suspend it in H2O and add aqueous NaOH until it dissolves, filter and acidify with dilute HCl. Collect the dye, dissolve it in hot EtOH (solubiUty is lOOmg/L at ca 25°) concentrate to a small volume and allow to cool. The solubility of the Na salt in H2O is 0.4mg/ml. [Mann Yoe Anal Chim Acta 16 155 1957, Mann Yoe Anal Chem 28 202 1956]... 

Xylidyl blue (Magon) Magnesium forms a colored complex with sulfonated Magon in a strongly basic medium. The absorbance maximum of the complex is at 548 nm. Calcium interference is avoided by the addition of ethylene-bis-(oxyethylene-nitrilo)-tetraacetic acid (EGTA) and interference by heavy metals by using cyanide. 

For determination of magnesium in clinical laboratories AAS is the method of choice. Spectrophotometric tests (titan yellow, xylidyl blue, magon) have proved less reliable in comparison with methods based on fluorimetry [27], nuclear magnetic resonance [28], and enzymatic assays [29]. 

Atomic absorption spectroscopy is a preferred method in clinical chemistry. However, UV/Vis spectrometry by use of chelating methods combined with photometry of chromophores offers simple and fast approaches. Examples are methods recommended by the National Committee for Clinical Laboratory Standards (NCCLS 1990) taking ferrocene for Fe, eliminating interferences by Cu by addition of thiourea. Mg is determined by addition of xylidyl blue, Ca by use of o-cresolphthalein or arsenazo complexes. Interferences by Mg are reduced by addition of 8-hydroxyquinoline. Further chromophores and complexing agents are discussed in subsequent chapters and elsewhere [39]. 

Test with Xylidyl Blue on ion exchange resin beads... 

The dyestuffs Xylidyl Blue I and II 4 -hydroxy-3-[2-hydroxy-3-(2,4 -xylylcarbamoyl)naphthylazo]benzeneand its sulfonic acid (Magon I and II) give a purple color with magnesium in alkaline medium. With the aid of ion exchange resins, this forms the basis of a very sensitive spot test for magnesium. ... 

Procedure. Dowex 1X1 (50-100 mesh) is treated with 20 times its volume of a 0.01 % solution of Xylidyl Blue I or II in ethanol. A drop of the test solution is mixed on a spot plate with one drop each of 0.5 iST sodium hydroxide, saturated aqueous glucose and 50% aqueous triethanolamine to make the pH 10-12. A few beads of the treated resin are then added. A purple color appears in the presence of magnesium. 

Hydroxyquinoline 8-Hydroxyquinoline + butylamine Titan yellow Xylidyl blue... 

Dimethylpheny[)amino carbonyl]-2-hydroxy-l-naphthalenyl]azo] 4-hydroxybenzenesulfonic acid, 9CI. 1-Azo-2-hydroxy-3- 2,4-dimethylcarboxanilido)naphthalene- r - 2-hydroxybenzene-5-sulfonic acid). Xylidyl blue I [36505-52-9]... 

---