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Topic: pka value  (Read 5246 times)

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Offline ash2006rf

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pka value
« on: January 17, 2008, 07:37:00 AM »
hi
im using HPLC to determinatoin sudan dyes in food
but my question i want to know the pka value for these dyes
i will be thanx for answer my quesion
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Offline AWK

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Re: pka value
« Reply #1 on: January 17, 2008, 08:44:39 AM »
http://chromatographyonline.findpharma.com/lcgc/data/articlestandard//lcgc/432007/467324/article.pdf

Note pKa values for these dyes are rather low (derivatives of naphtols), and moreover they can easily change because Sudan dyes absorb a visible light, and excited states show different pKas.
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Offline cqyc007

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Re: pka value
« Reply #2 on: July 29, 2010, 01:51:16 AM »
dear AWK,
    any references to support your opinion "Note pKa values for these dyes are rather low (derivatives of naphtols), and moreover they can easily change because Sudan dyes absorb a visible light, and excited states show different pKas."
     Thanks.
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Offline AWK

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Re: pka value
« Reply #3 on: July 29, 2010, 05:09:45 AM »
You re very lazy. The first few google links on the question (even the first): Pka excited states
throw some light on your problem
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