Cellulose polyamide mixtures, dyeing

The separation characteristics of a considerable variety of other TLC supports were also tested using different dye mixtures (magnesia, polyamide, silylated silica, octadecyl-bonded silica, carboxymethyl cellulose, zeolite, etc.) however, these supports have not... 

The separation characteristics of a considerable variety of other TLC supports were also tested using different dye mixtures (magnesia, polyamide, silylated silica, octadecyl-bonded silica, carboxymethyl cellulose, zeolite, etc.) however, these supports have not been frequently applied in practical TLC of this class of compounds. Optimization procedures such as the prisma and the simplex methods have also found application in the TLC analysis of synthetic dyes. It was established that six red synthetic dyes (C.I. 15580 C.I. 15585 C.I. 15630 C.I. 15800 C.I. 15880 C.I. 15865) can be fully separated on silica high-performance TLC (HPTLC) layers in a three-solvent system calculated by the optimization models. The theoretical plate number and the consequent separation capacity of traditional TLC can be considerably enhanced by using supports of lower particle size (about 5 fim) and a narrower particle size distribution. The application of these HPTLC layers for the analysis of basic and cationic synthetic dyes has also been reviewed. The advantages of overpressured (or forced flow) TLC include improved separation efficiency, lower detection limit, and lower solvent consumption, and they have also been exploited in the analysis of synthetic dyes. 

It has become apparent that, in addition to the known disadvantages of loosely spread layers, the solvents quoted [71, 82] cannot necessarily be used without difficulty. The possibilities of separating numerous dyes, using TLC, have been subsequently investigated. Along with siUca gel G and alumina G and H (Firm 88), 1 1 mixtures of both, MN-cellulose powder, acetylated MN-cellulose powder (Ac) (Firm 83) and polyamide powder (Firm 153) have proved useful in thin-layer chromatographic separation. 

Disperse colouring materials are used principally for colouring cellulose acetate, polyamide and polyester fibres. Their chemical structure is similar to that of the fat-soluble dyes. They belong to the compound classes of nitrodiphenylamine derivatives and azo- and anthraquinone dyes without a sulphonate group. They are more or less easily soluble in organic solvents but insoluble or difficultly soluble in water. Mixtures of disperse dyes can be separated on alumina columns, using solvents such as ether, methylene dichloride, ethyl acetate and tetrahydrofuran [71]. PC-separations on cellulose paper are incomplete [14, 30, 31, 73, 85]. Separations are better on acetyl-paper [29, 30, 43] or pre-treated paper [19, 20, 25, 44, 73]. 

Food dyes are extracted from foods by using adsorbents such as wool fibers, powdered polyamide, cellulose exchange resins, or RP cartridges (Sep-pak Cis), which is the method of choice for a fast and easy cleanup. After desorption of the colorants and filtration, the solution is analyzed by either ion-pair or reversed-phase LC. Ion-pair LC uses water acetone mixtures (80 20) with tetrabutylammonium chloride added as ion-pair agent and Cig or Cg columns. As for RPLC, a combination of phosphate buffer methanol, water acetonitrile, and methanokacetone are commonly used. Gradients are used to allow the separation of the different classes of... 

---