Indigo blue

Analysis. Indium can be detected to 0.01 ppm by spectroscopic analysis, using its characteristic lines in the indigo blue region, at wavelengths 4511.36, 4101.76, 3256.09, and 3093.36 nm. Procedures for the quantitative deterrnination of indium in ores, compounds, alloys, and for the analysis of impurities in indium metal are covered thoroughly in the Hterature (6). 

Enzymatic stone-washing is performed either entirely without stones or sometimes by a combination of stones and enzymes. CeUulases are used to attack the surface of the cellulose fiber, but leave the interior intact. Denim garments are dyed with indigo blue, which stays on the surface of the yam. The ceUulase partiy hydrolyzes the surface of the fiber, and the indigo blue is partiy removed. Either neutral-type ceUulases acting at pH 6—8 or acid-type ceUulases acting at pH 4—5 are used for these processes. 

Indium and thallium were also discovered by means of the spectroscope as their names indicate. Indium was first identified in 1863 by F. Reich and H. T. Richter and named from the brilliant indigo blue line in its fiame spectrum (Latin indicum). Thallium was discovered independently by W. Crookes and by... 

It yields a characteristic reaction with bromine. If a few drops are, dissolved in 3 c.c. of glacial acetic acid and a little bromine vapour allowed to pass down the tube, a fine crimson colour forms which rapidly extends to the whole of the liquid and soon changes to violet and then to indigo blue with phosphoric acid, the acetic acid solution gives a rose madder colour at the junction of the liquids, and when the liquids are mixed, the colour changes to crimson and then slowly to violet. Baker and Smith consider that the sesquiterpene contains one double linkage. Semmler considers that it is a mixture of at least two bodies, one a bicyclic and the other a tricyclic sesquiterpene. 

Indig, m. indigo, -blau, n. indigo blue, -blau-schwefelsaure, /. = Indigoblauschwefel-... 

WD-50 s two bartenders wore raw-indigo blue jeans and dark cherry shirts. The arriving clientele, with their flattened hair, small bowling-bag purses and mini trench coats, could have stepped out of a dressing trailer parked on Clinton Street and walked into the restaurant as a group. 

Was prepd by Wieland and Hess (Ref 2) by acidifying its K salt with mineral or acetic acids, but it proved to be very unstable. It is si sol in warm ale, from which it can be crystd K salt KCH02N2 indigo-blue needles from aq ale mp, decomps explosively ca 194° with a loud report. Was prepd (Ref 2) by adding ale K hydroxide to a mixt of hydroxylamine hydrochloride and formamidoxime (Ref 1) in methanol at 50—60°. Sol in w, si sol in ale. Explds on heating or impact... 

Figure 5 Chromogenic BVMO assay using 3-acetyl indole resulting in the formation of indigo blue. ...

The natural dyes industry was also a large, sophisticated, and worldwide employer. Master dyers made a wide range of reasonably fast colors and handed down secret dye recipes to their apprentices. Europe s two staple dyes were madder red from the Mediterranean and indigo blue from India. Other natural dyes included violet from lichens dark red from the forget-me-not family brown from African aloe plants and black from tumorlike... 

Attempts to prepare 2-diazo-3-oxindole failed. In fact, base decomposition of the isatin-2-tosylhydrazone under conventional conditions with potassium hydroxide at room temperature led to the potassium salt (64JOC3577). When an aqueous solution of the potassium salt was heated at 70°C, indigo blue was obtained in 62% yield. 

Indium was discovered by Reich and Richter in 1863 in Germany during spectroscopic observations of local zinc ores. The new element was named indium after its characteristic indigo blue spectral lines. Although widely distributed in nature, its concentration is very low, estimated to be about 0.1 mg/kg in the earth s crust. It is found mostly in zinc sulfide ores and to a lesser extent in sulfide ores of iron and copper. The metal does not occur in free elemental form in nature. 

Dyestuffs of plant origin include indigo blue, used to dye jeans. A poison of detective novel fame is strychnine, obtained from the plant resin curare (Box 1.6). 

Analysis. The colorimetric method for In is capable of a detection limit of 20 ppb. Indium or an In compound in the flame gives an indigo blue color (451.1 nm). This photon line allows for the spectrophotometric determination ofinby AAS (atomic absorption flame spectroscopy). The method is sensitive to about 300 ppb. With ETAAS, this limit drops to 10 ppb, as it does with ICPAES. ICPMS drops the limit to 0.01 ppb. Alizarin detects In, as well as Al, but the reaction with Al can be masked by addition of F to a spot test. The limit of detection is about 1 ppm. 

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