Questions tagged [dye]

For questions related to compounds for producing color (intentional or not).

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I need to test fabric for arsenic, and I've found 141-year-old guidance. Is it legit?

I'm a book and paper conservator, and a few years ago had four books to restore. Their endpapers were this gorgeous green silk, but they were badly dry rotted, and needed to be removed. I suspected ...
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DNA staining agent with good absorbance at 532 nm

I need to stain some double-stranded DNA with an intercalating fluorescent dye. For imaging, I am using a microscope setup equiped with a 532 nm green laser. What is the staining agent of choice to ...
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Fluorophores with high quantum yield and low lifetime

Does anyone know of any fluorophore or family of fluorophores with a relatively high fluorescence quantum yield (larger than 0.1) and a short lifetime (below hundreds of picoseconds)? I have been ...
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Why don't universal indicator solutions react with themselves?

Universal indicator is a pH indicator made of a solution of water, 1-propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, sodium bisulfite, and thymol blue that exhibits ...
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Has anyone added dyes to a mixture about to separated by chromatography in order to visualize where the desired product lies?

Usually in preparative chromatography one needs to know when the desired substance to be separated is coming down the pike. Often this required some sophisticated instrumentation. But, it occurred to ...
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Why are colloidal sol particles of acidic dyes negatively charged and basic dyes positively charged, when it should be the other way round?

From NCERT Class 12 Chemistry; Sri Aurobindo Marg, New Delhi, India; January 2019; p. 136: Colloidal solutions of basic dyes like methylene blue are positively charged whereas colloidal solutions of ...
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What replaced lead-based pigments? [closed]

In the 1960s and before, even black and white letters had some lead from the actual metallic letters used by typesetters—some rubbed off. Same thing with books printed before 1970 or so and libraries ...
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Looking for a non-toxic, environmentally safe highly colored or intense dye

I need a dye that is "highly colored" or intense. I want to put it in water and flow the water in the form of a liquid sheet that is around 100 microns thick. A number of spray nozzles use ...
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Why is Tyrian purple called 6,6′-dibromoindigo?

If the two bromines are attached at opposite ends of the molecule, why are they both labelled with a 6? Also, why is 6,6′-dibromoindigo not called 1,1′-dibromoindigo if carbons in a ring are numbered ...
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Conversion of Erythrosine to Fluorescein

I am a home-chemist and I love dyes. I recently got my hands on sodium salt of erythrosine (tetra-iodinated fluorescein). I want to convert erythrosine to fluorescein. I speculate that using dilute ...
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Rate constants and their relationship to quantum yields

Question A dye molecule has a singlet excited state lifetime of $\pu{0.85 ns}.$ The quantum yield of triplet formation is $35~\%.$ What is the rate constant for intersystem crossing from the ...
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Indigo and the Environment: is it that bad?

TL;DR: In what aspects are the products of the indigo vat dyeing process (sodium sulphate, sulphite and thiosulphate ions) harmful to the environment or to living beings? I was recently looking into ...
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Mixing ink with alcohol, MEG and water

First of all, I'm not a chemist and my knowledge in chemistry is not that extensive. However, I would like ask the following question: are there any chemical reasons that would explain that mixing a ...
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3 votes
1 answer
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Which compounds react positively in the aniline dye test?

I read that to test for the presence of phenol groups in an organic compound the aniline dye test can be performed. If the solution has phenol present it gives a red or orange precipitate to confirm ...
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12 votes
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Looking for a dye which emits around 680 nm

For a specific experiment, I'm looking for a dye which would emit around 680 nm. Preferably one I could buy easily commercially. Are there any databases which might give the emission spectra of ...
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Is there dye that attaches only to human DNA? [closed]

I am looking for simple way to tell if blood stain is from human blood or some other animals. I know there are fluorescent DNA dyes, but is there dye that only attaches to human DNA?
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Does there exist a dye that will primarily bind with water in a water/oil emulsion?

I'm wondering if there exists a type of dye that will bind primarily with water when introduced to a water/oil emulsion. That way if the water is centrifuged to the bottom of the vial, it will be dyed ...
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Reduction of triphenylmethane dyes in ink

Right now I'm trying to explain why the ink from an ink pen turns colourless in water. I know that the pH is responsible as it breaks apart the conjugated system of double bonds. I'm just not sure on ...
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How can I preserve chlorophyll for long periods of time?

I'm currently working on a XIX century photographic process called Anthotype. It relies on organic colored substances that fade when exposed to sunlight. For the substances I've tried alcoholic ...
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5 votes
1 answer
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How to make equal density pool dye without diffusion

I have a leak I have been struggling to find in my in-ground pool. I am losing about 1/4" of water per day and I believe the issue is one of the fittings in the bottom of the pool. There are two ...
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Why does SYBR green emit more signal when bound to DNA?

Principle of SYBR Green SYBR Green I (SG) is an asymmetrical cyanine dye used as a nucleic acid stain in molecular biology. (wiki) This molecule is commonly used in qPCR to meassure the ...
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Mechanism of formation of 2-naphthol red dye (aka Sudan 1)

As you can see in the image diazonium can attack at 2 different positions to form different products then why only the first product is correct? As there are two ortho positions available why does it ...
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Strange green and gold coloured chemical [closed]

I have a reagent bottle with an unknown chemical that came with some other lab gear about 30 years ago, I stumbled on it again when clearing out some old stuff. It is a standard brown glass Merck of ...
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Do indigo and leuco-indigo have fully conjugated pi systems?

I've just come across a figure indicating the positions of conjugated bonds in indigo and leucoindigo, and I'm quite confused about why both molecules aren't fully conjugated. My reasoning is as ...
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Anthracine blue composition

In 1873 a German chemist named Springmühl announced a derivative of alizarin which acted as a blue dye and he sold this dye for a high price. The dye was sometimes called "anthracine blue" and ...
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