Phenylfluorone

Luskima and Syavtsillo [120] have described a spectrophotometric procedure utilising phenylfluorone for the determination of organotin compounds in water. 

Germanium solutions in the presence of phenylfluorone (1) and lauryldimethylam-monium bromide yield coloured compounds, Zmax 508 nm, el.60 x 105. This allows germanium determination at concentrations of 8-80 Xg/L. Only Sb, Sn, Cr(VI) and Mo interfere with the analysis17. Precipition and filtration of the Ge(IV)-l complex formed in... 

An alternative to AAS for the end analysis of stannane generated by hydrogenation, could be collection in permanganate solution and spectrophotometric determination with phenylfluorone (3). This was applied to submicrogram Sn/L concentrations in fresh and marine waters276. Determination by hydride generation-AAS was found to be about 20 times more sensitive than by spectrophotometry of the phenylfluorone (3) complex28. 

In the experiment shown in Fig. 10.7b phenylfluorone acting as hole trapper was... 

Die beste Methode ist wohl die colorimetrische Bestimmung mit Phenylfluoron 42). 

Germanium mit Phenylfluoron. 2. Mitteilung. Mikrochim. Acta [Wien]... 

With metal ions, some organic reagents form coloured compounds that are sparingly soluble both in water and in organic solvents. They are either polynuclear complexes, such as formed by phenylfluoron with Sn(IV) or with Ge(IV), or adsorption-type compounds such as those formed by titanium yellow with Mg. In such cases, the absorbance is measured for suspensions of coloured pseudo-solutions stabilized with protective colloids [e.g., gum arabic, gelatine, poly(vinyl alcohol)]. 

Antimony was determined in coal and steel with the use of mandelic acid [80]. Phenylfluorone derivatives were applied in determination of Sb in non-ferrous metal alloys... 

Other organic reagents recommended for determining chromium include phenylfluorone [49] and o-nitrophenylfluorone (in the presence of CTA) (e = 1.1-10 at 582 nm) [50], Methylene Blue (e = 8.3-10" ) [51], Pyrogallol Red [52], morin [53], and 2,2 -diquinoxalyl [54]. Chromium was also determined by a sensitive method based on the ion-associate of Cr(VI) with Rhodamine 6G in aqueous solution containing poly(vinyl alcohol) [55], and after extraction into toluene [56]. 

Many other organic reagents have been used to determine Co, including phenylfluorone (in the presence of CP, e = 1.16-10 at 620 nm) [84,85], and ferrozine [86,87]. A very sensitive method has been based on the complex of Co with a,p,y,5-tetrakis(4-sulphonyl)porphyrin (Co replaces Cd in the complex) (e = 2.4-10 at 432 nm) [88,89]. ]. Less sensitive methods for Co utilize EDTA, DCTA, EGTA and NTA ( = 200-300 nm) [90]. 

The phenylfluorone method has been used generally for determining germanium. The sensitivity of this method is higher in the presence of surfactants. Methods based on ion associates with basic dyes deserve notice because of their high sensitivities. 

At wavelengths >500 nm the interference from the absorption of the reagent is slight. The molar absorptivity of the solution of the Ge-phenylfluorone complex, under the conditions given in the procedure below, is 5.3-10 at 510 nm (a = 0.73). 

Phenylfluorone also forms coloured complexes with many metals, e.g., Sn, Sb, Ti, Fe(III), Nb, and Ta. Low concentrations of arsenic, silicon, and fluoride do not interfere in the formation of the germanium complex. Citric and oxalic acids are used to mask Mo, V, Sn, and Ti [19,20]. Preliminary separation of germanium as GeCU by extraction or distillation renders the phenylfluorone method specific for germanium. 

When the colloidal solution of germanium phenylfluoronate is shaken with CCU, the precipitate agglomerates at the interface. After removal of nearly all the CCLt and the aqueous solution (containing the excess of phenylfluorone), the precipitate is dissolved in acetone and the absorbance measured [21]. High sensitivity (e= 1.2-10 at 495 nm) is obtained, if phenylfluorone is added to a chloroform extract of Ge complex with N-p-chlorophenyl-2-furohydroxamic acid [8]. A DMF solution of phenylfluorone was also added to a toluene extract of GeCL (e = 7.1 10 at 525 nm [3].An aqueous solution of Ge was also... 

Phenylfluorone, 0.01% solution in methanol. Dissolve 25 mg of the reagent in methanol containing 2.5 ml of cone. HCl, and dilute the solution with methanol to volume in a 250-ml standard flask. A method for purification of phenylfluorone has been proposed [23]. 

Determination of Ge. To a 25-ml standard flask, add the solution obtained (or an aliquot thereof) containing not more than 25 pg of Ge. Add water to 10 ml, 1 ml of 1% gum arabic solution, 5 ml of phenylfluorone solution, 5 ml of methanol, and 1 ml of acetate buffer, mixing the solution after the addition of each reagent. After 5 min, dilute the solution to the mark with HCl (1+4), and measure the absorbance at 510 nm against a blank solution. 

Cetyltrimethylammonium bromide (CTA) has been found to increase greatly the sensitivity of germanium determination with phenylfluorone [5,25]. 

Phenylfluorone, 0.001 M (-0.03%) solution. Dissolve 80 mg of the reagent in 100 ml of ethanol containing 1 ml of cone. HCl, then dilute the solution to 250 ml with ethanol. The solution is stable for one month. 

To a slightly acidic sample solution (about 10 ml in a 25-ml standard flask) containing not more than 8 pg of Ge, add 2 ml of 10% ascorbic acid solution, 3 ml of cone. HCl, and 2 ml of CTA solution. Then add 2 ml of phenylfluorone solution, dilute to volume with water, and mix. After 5 min, measure the absorbance of the solution at 507 nm vi. a reagent blank. 

In addition to phenylfluorone, a number of other 2,3,7-trihydroxy-6-fluorones have been recommended for determination of germanium. Disulphophenylfluorone (e = 9.0-10" ) reacts under the conditions similar to those of fluorone [29]. Some trihydroxyfluorones react with Ge in the presence of antipyrine and bromide (also f, SCN, and CIO4) to form compounds extractable with CHCI3 or similar solvents [30]. The sensitivity of determining Ge with various fluorones increases in the presence of cationic surfactants. The following systems have been recommended salicylfluorone with CP (e = 1.2-10 at 530 nm) [31], tetrabromo-salicylfluorone with CP (e = 1.3 10 at 520 nm) [32], and o-chlorophenylfluorone with CTA (e = 1.8-10 at 516 nm [33]). A non-ionic surfactant Triton X-305 has been used in the case of disulphophenylfluorone [34]. 

---