Dye extract

HPLC-UV is a popular technique to analyse textile dyes extracted from polyester fibres [697], acidic dyes from wool fibres [698] and basic dyes from acrylic fibres [699]. HPLC provides better sensitivity and resolution than TLC [697-699]. GE-RPLC has been used for the determination of 18 disperse dyes (e.g. Navy D-2G-133, Orange CB, Yellow D-3R and Red D-2G) extracted from polyester [700]. Compared with the traditional TLC method, HPLC offers lower detection limits, better observation of contaminant peaks, and reproducible quantitative results. HPLC has also been used to determine azo dyes [701,702]. 

Madder, also known as Turkey red, is a scarlet dye extracted from perennial herbaceous plants of the order Rubiacea, of which there are about 35 species (Chenciner 2001 Farnsworth 1951). A well-known plant from this order is Rubia tinctorum, found naturally in Palestine and Egypt, abundant in Asia and Europe, and extensively cultivated in the ancient world, was widely used for production of the dye since remote antiquity. The use of madder for dyeing seems to have originated in the Middle East it was identified in many textiles found in Egyptian tombs and in woolen fabrics from the Judean Desert in Palestine. It was also used by the ancient Persians, Greeks, and Romans. Madder from other varieties of Rubiacea plants were used by the Incas in ancient Peru (Schaefer 1941 Fieser 1930). 

The natural dye was extracted by immersion of fresh Morns nigra (black mulberry) in ethanol for several hours. The pure violet dye extract, a blend of p-carotene and Morus nigra, and a composite blend of chlorophyll A and B, carminic acid, trans-P-carotene, and Morus nigra extracts (hereafter called Mix) were deposited on Ti02. 

Cochineal and lac dye can be studied by HPLC with spectrophotometric and NI ESI MS detection. [34] In cochineal, carminic acid appears as a dominant colouring agent. In lac dye extracts, the signal at m/z 536 corresponding to a quasi-molecular ion of laccaic acid A is observed as the dominant one. [19]... 

A similar analysis of cochineal can be performed with the use of CE with ESI MS detection. The results are similar to those obtained with HPLC MS.[20] In the lac dye extract, the signal of laccaic acid A is found in the mass spectrum as the dominant one at m/ z 536. However, a second peak is observed on the electropherogram, and the eluted substance can be identified as laccaic acid E, on account of the mass spectrum which consists of the following signals at m/z 494 [M H], 476 [M H20 H] and 450 [M C02 H]. ... 

The optimized RPLC UV-Vis ESI MS method for all typical blue colourants (indi-goids, hematein, tannins, anthocyanins and selected flavonoids) was used for the identification of dyes extracted from a thread taken from an Italian tapestry of unknown origin from the collection of the National Museum in Warsaw (Poland). It was found that to obtain the red-blue colour of the fibre a mixture of dyestuffs was probably used. The presence of indigotin, tannic and ellagic acid (at m/z 301, NI), as well as carminic acid, suggested the use of indigo and cochineal. Reseda luteola could also have been used due to the presence of luteolin and apigenin. 

M. Trojanowicz, J. Orska Gawrys, I. Surowiec, B. Szostek, K. Urbaniak Walczak, J. Kehl and M. Wrobel, Chromatographic investigation of dyes extracted from Coptic textiles from the National Museum in Warsaw, Stud. Conserv., 49, 115 130 (2004). 

Azo dyes extracted from waste sludges can by identified by GC-MS after H2/Pd cleavage to aromatic amines according to reaction 3, in a microreactor mounted on the injector123. 

Earlier we found that the addition of alkyl-modified poly(propylene imine) dendrimers to polypropylene leads to fibers which can be dyed in conventional acid or disperse dyeing processes [3]. The alkyl chains make the additive compatible with the polypropylene matrix, while the polar core of the dendrimer can act as a receptor for the dye molecules. This host-guest behavior is analogous to the principle of the dendritic box as described by Meijer et al. [30] and elaborated by Baars et al. for dye extraction processes [31]. 

This procedure is more widely used in pharmacopoeial assays than the dye extraction procedure. Excess potassium iodide is added to an aqueous solution of the analyte, which is a lipophilic cation. A lipophilic ion pair is formed between the cation and the iodide ion and is then removed by extraction into an organic phase such as chloroform. The excess iodide remaining in the aqueous phase is then titrated in concentrated HCl (> 4 M) with potassium iodate. The iodate oxidises iodide to E, which immediately reacts with Cl to give ICl resulting in the following equation ... 

In addition to organic dyes, natural dyes extracted from plants can be used as photosensitizers [36,140,141]. A nanocrystalline 2 solar cell using a san-talin dye extracted from red sandalwood can produce 1.8% efficiency under 80 mW/cm2 irradiation [141]. Cherepy et al. reported that a nanocrystalline 2 solar cell using flavonoid anthocyanin dyes extracted from blackberries could convert sunlight to electrical power with an efficiency of 0.6% (Jsc = 1.5-2.2 mA/cm2 and Voc = 0.4-0.5 V) under AM 1.5 [36]. 

ML Puttemans, L Dryon, DL Massart. Evaluation of thin-layer, paper and HPLC for identification of dyes extracted as ion-pair with tri-n-octylamine. J Assoc Off Anal Chem 65 730-736, 1982. 

Dye woods and barks are sold in lumps or ground or powdered, or as dyeing extracts. The latter are aqueous decoctions of the materials and are met with either as more or less dense liquids or in the dry state as cakes, irregular or, rarely, crystalline fragments, or powder. They are usually brown or yellowish and they have a sweet taste, almost or quite free from astringency they bum with emission of the odour of burning vegetable matter and leave little ash they are more or less completely soluble in water and sometimes also in alcohol. 

Dyeing extracts may be mixed or adulterated with tanning extracts and may also be adulterated with artificial organic dyes or -various inert substances, either organic (molasses, glucose, dextrin, starch, glue) or inorganic (sodium sulphate and other soluble salts, and insoluble substances). 

Detection of Artificial Organic Dyes.—Dyeing extracts are sometimes " improved with artificial organic dyes. Unless these are present in very small quantity, they may be suspected from the odour emitted when the extract is burnt. Moreover, the colour reactions of dyeing extracts are more or less altered by the presence of artificial dyes. 

When shaken with alcohol, ether, benzene, nitrobenzene, etc., dyeing extracts as a rule do not colour these solvents, whereas artificial organic dyes dissolve in some of them and thus colour them. In some cases the extraction may be effected after the substance has been rendered acid or alkaline. 

Artificial organic dyes may also be detected in dyeing extracts by dyeing tests and subsequent examination of the colouring matters thus fixed on the fibre (see Textile Fibres). 

As regards starch, this may be investigated microscopically, best in the residue left after extraction of the dyeing extract with ether and alcohol. 

Dyeing Value.—The best criterion of the dyeing value of a dyeing extract is obtained by a small dyeing test, which is made also on a genuine extract for purposes of comparison. This test is carried out differently with different extracts and according to whether the colour is to be applied to cotton, wool or silk most commonly the tests are made with wool. 

Besides being subjected to the tests indicated for dyeing extracts in general, logwood extract is examined as follows. 

In addition to the tests and determinations already indicated for all dyeing extracts, the following tests are made in this case. 

Indigo, especially the natural product, may be adulterated with mineral substances (sand, clay, slate, brickdust, barium sulphate, chalk, graphite), starch, dextrin, gum, resin, dyeing extracts, Prussian blue, etc. 

It is often adulterated with cochineal exhausted of its colouring matter and then dried, or moistened with solutions of dyeing extracts (especially red wood) and is frequently mixed with talc, gypsum, or heavy spar. It is sometimes mixed also with leaden fragments or filings. The tests to be made are as follows ... 

Litmus is a purple dye extracted from lichens and sea weeds. Lichens grow abundantly along the Mediterranean coast. Litmus readily dissolves in water to form a purple solution. This solution is used as an indicator to find out whether a solution is acidic or alkaline. Acid turns the litmus solution red and the base turns the litmus solution blue. 

Blue dye is extracted from the leaves of the woad plant (an old world plant). Dyes extracted from plants are called vegetable dyes. People obviously knew how to extract dyes from plants. 

Figure 5 shows the comparison of the madder dyes taken from the Adler-dalmatika with samples of Rubia tinctorum, alizarin, and purpurin by TLC. The dye extracted from the sample of the Adlerdalmatika with dilute sulfuric acid is unmistakably madder. 

Figure 5. Identification of the madder dyes in the Aldlerdalmatika by TLC comparison. 1, dyes extracted from the Aldlerdalmatika by diluted sulfuric acid 2, madder dyes 3, alizarin 4, purpurin.

Figure 9. TLC comparison of the red insect dyes in the Karabagh carpets, figures 7 and 8, after dissolving the dye extracts in different organic solvents. 1 and 2, extracts of the Karabagh carpet (figure 7) 1, soluble in ether 2, soluble in ethyl acetate + methanol 3 and 4, extracts of the Karabagh carpet (figure 8) 3, soluble in ether 4, soluble in ethyl acetate + methanol 5 and 6, extracts of Armenian cochineal S, soluble in ether 6, soluble in ethyl acetate + methanol 7, Polish cochineal 8, American cochineal 9, kermes 10, laccaic acids (XXVIII - XXXII) 11, erythrolaccin (XXXIII) 12, deoxyerythrolaccin (XXXTV).

This last point is important since it has prevented many researchers from successfully determining the spectral characteristics of the visual dyes extracted from retinas for many years. 

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