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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: ash2006rf on January 17, 2008, 07:37:00 AM

Title: pka value
Post by: ash2006rf 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

Title: Re: pka value
Post by: AWK 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.

Title: Re: pka value
Post by: cqyc007 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.

Title: Re: pka value
Post by: AWK 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