Dye xylenol orange

Surfactant solutions above the c.m.c. can solubilise otherwise insoluble organic material by incorporating it into the interior of the micelles for example, the dye xylenol orange dissolves only sparingly in pure water but gives a deep red solution with sodium dodecyl sulphate present above its c.m.c. 

In another study, the Anslyn group has employed receptor 6 in combination with xylenol orange to determine the concentration of Ca and citrate in flavored vodkas (Figure 7.3) [16]. Receptor 6 can bind to the dye xylenol orange or to citrate. The dye and citrate, on the other hand, can both form complexes with Ca. The addition of samples containing Ca and citrate to a sensor comprised of receptor 6 and xylenol orange was therefore expected to result in a complex dynamic mixture of aggregates. 

Various phthalein dyes have been proposed for detection and determination of H2O2, with different operating principles, such as direct measurement of the dye and complex formation. The FOX assay is based on the oxidation of Fe(II) to Fe(III), followed by complex formation of the latter ion with Xylenol Orange (71). The concentration of the complex is measured at = 560 nm (e = 4.3 x 10 The linearity... 

ALTERNATE PROTOCOL DETERMINATION OF PEROXIDE VALUE BY MEASUREMENT OF IRON OXIDATION The ferrous oxidation/xylenol orange (FOX) method is based on the ability of lipid peroxides to oxidize ferrous ions at low pH. The resulting oxidation is quantitated by using a dye that complexes with the generated ferric ions to produce a color that can be measured spectrophotometrically. Peroxide values (PVs) as low as 0.1 meq active oxygen/kg sample can be determined with this method, providing a distinct advantage over iodometric titration. 

In the modified FOX method (see Alternate Protocol), the 5- min incubation period must be strictly adhered to because the color intensity changes with time. Incubation for an additional 5-min increases the absorption of the blank. Jiang et al. (1992) proposed that the changes in color with time might result from instability of the dye on further oxidation of the sample. The color of the iron-xylenol orange complex changes from reddish to purple as the level of peroxides in the sample increases. This causes a decrease in absorbance at 560 nm. As noted in the protocol itself, the content of Fe3+ versus absorbance is not linear over wide concentra-... 

A different vesicular photoimaging material consists of an assembly of lipid vesicles sensitized with rhodopsin. In one system the vesicles can be filled with a solution containing Co2+, and the solution outside the vesicles can be free of metal ions but contain a chelating indicator dye such as xylenol orange (101). The whole assembly can be coated, and when exposed to actinic radiation the vesicles are disrupted in exposed areas and release Co2+ ions, which are complexed by the dye indicator, thereby forming an image.253... 

Wennemers and Still have recently reported that common, commercially available dyes (such as rhodamine methyl ester, crystal violet, Safranine O, phenol red, xylenol orange, etc.) bind certain acylated tripeptides attached to hydrophilic poly(ethylene glycol)-polystyrene beads with high selectivity in water [76], They suggested that hydrophobic interactions and electrostatic interactions are the driving forces for the binding. 

The following triphenylmethane dyes have been employed for determination of Sc similarly to Xylenol Orange Methylthymol Blue [33], Chrome Azurol S [34,35], Chromal Blue G [36], and Eriochrome Brilliant Violet B [37]. Much higher sensitivities have been obtained in the presence of some cationic surfactants [38 0]. In the method with Chrome Azurol S and Zephiramine, the e value is 1.5-10 at 610 nm, and in the method with Eriochrome Cyanine R and CP, e = 9.2-10" at 600 nm [40]. When o-hydroxy-quinonephthalein and CP are used, the molar absorptivity is 1.1-10 at 555 nm [41], Scandium has been determined with the use of Nile Blue in a poly(vinyl alcohol) medium [42]. 

Selenium has been determined with 5,5-dimethyl-1,3-cyclohexanedione [51], 6-amino-1-hydroxynaphthalenesulphonic acid [52,53], and l-aminonaphthalene-7-sulphonic acid [54], Determinations of Se involved also the following dyes Rhodamine B [55], Methylene Blue [56], Xylenol Orange [57], and Rhodamine 6G (by the amplification method, in iodide medium, after oxidation of iodide to iodine, and reaction of the I03 with the dye) [58]. 

Ill, Xylenol Orange (XO), Alizarin Complexone (AC), and Methylthymol Blue (MTB). A few reports have appeared using dyes to extract transition metal ions in ABSs [65,66. ... 

Nakayama, H. Tachiyashiki, S. Ishii, M. Preparation of high purity Xylenol Orange and isolation of a new metaUochromic dye by cation exchange column chromatography on SP-Sephadex. Anal. Sci. 1989, 5, 619-621. 

Triphenylme thane dyes, such as xylenol orange and methylthymol blue, are widely used in spectrophotometiic determination of rare earths. Veber (1979, 1981) studied several triphenylmethane dyes by polarographic methods. It was found that the quinoid group and the carbonium ion are responsible for the reduction wave in polarography. Zhang et al. (1984) investigated and compared the polarographic... 

Xylenol orange (XO) is a triphenyhnethane dye, which is used as an indicator. It is widely used in spectrophotometry for the determination of rare earths. Veber et al. (1979) studied the polarographic behavior of XO and showed that the carbonyl group in the molecule reduces via two steps. In the first step a free radical is formed and in the second step this free molecule is reduced. At high acidity the free radical disproportionates into XO and a final product, so the second wave disappears. At pH 4-5, the rate of disproportionation is very slow, hence we may obtain two separate waves of approximately equal height. 

There are now many metallochromic indicators which may be used in complexometric titrations. For successful end-point indication the pK value of the metal-dye complex should be at least 4 units less than that of the metal-EDTA complex which is formed during the titration if the difference is less than 4 units the titrant is unable to compete satisfactorily with the indicator dye and a sluggish end-point results. The indicators which are most widely used in the methods described in this book are solochrome black (for titrations carried out in ammoniacal solution), xylenol orange (for titrations carried out between pH 4 and 7) and catechol violet (for titration in mineral acid solution at pH 1 to 2). Table 63 lists the various indicators called for in methods in the monographs. Discussion of the merits of different indicators for specific purposes will be found in various parts of the book. 

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