Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: valeg96 on 02/01/2014 15:20:30

Title: What is the composition of E131 Patent Blue V?
Post by: valeg96 on 02/01/2014 15:20:30

What is the formula and composition of Patent Blue V aka E131 in EU? http://en.wikipedia.org/wiki/Patent_Blue_V (http://en.wikipedia.org/wiki/Patent_Blue_V) says:

Quote

It is a sodium or calcium salt of [4-(α-(4-diethylaminophenyl)-5-hydroxy- 2,4-disulfophenylmethylidene)-2,5-cyclohexadien-1-ylidene] diethylammonium hydroxide inner salt. It has the appearance of a violet powder.

The Italian page http://it.wikipedia.org/wiki/Blu_Patentato_V (http://it.wikipedia.org/wiki/Blu_Patentato_V) says:
 

Quote

C₂₇H₃₁N₂NaO₇S₂ (sale di sodio) C₅₄H₆₂CaN₄O₁₄S₄ (sale di calcio)

Do you know more about their % in the powder sold for cooking/baking (I suppose they are all similar)? The one i bought is produced by http://www.fioriocolori.com/coloranti/ (http://www.fioriocolori.com/coloranti/), if you are interested.
I need to make a solution for lab and having something more defined would be pretty nice, especially to define a concentration, i tried before but ended up with a horrible 1 mm³/150mL H₂O

Thanks a lot!

Title: Re: What is the composition of E131 Patent Blue V?
Post by: CliffordK on 02/01/2014 18:49:01

The product in pure form is a monovalent salt. 

If you buy it as a sodium salt, then you get one large molecule per unit.
As a calcium salt, you get two (and thus the C₅₄...)

Knowing the carbon/hydrogen formula doesn't really tell you what it looks like.  You need the full technical name or diagram to identify the chemical.

You can purchase it pure, or in a high purity form from chemical suppliers.  Sigma Aldrich is a big company, but there are many suppliers, and I assume also local vendors.
Patent Blue V Sodium Salt (Sigma Aldrich) (http://www.sigmaaldrich.com/catalog/product/sigma/21605?lang=en&region=US)
Patent Blue V Calcium Salt (Sigma Aldrich) (http://www.sigmaaldrich.com/catalog/product/fluka/74748?lang=en&region=US)

Note, the Sigma Aldrich page above notes that the chemical may be available with or without the OH on the ring with the sulfate groups.

Some interesting notes here including synthesis notes (http://www.efsa.europa.eu/en/efsajournal/doc/2818.pdf) on page 9.

As far as retail sales.  As a liquid, the chemical would certainly be diluted.  But, as a powder food colorant, it may still be diluted.  Your supplier should be able to list the ingredients if it is not being sold in pure form, especially if it is being sold as a food product.

Title: Re: What is the composition of E131 Patent Blue V?
Post by: valeg96 on 02/01/2014 18:58:05

Thanks CliffordK. just to let you know, I am currently trying to find an optimal concentration to use it as pH indicator. It ranges yellow-green-blue-red, but its path is unclear, i need to find an optimal concentration to identify the various steps.

Title: Re: What is the composition of E131 Patent Blue V?
Post by: CliffordK on 02/01/2014 23:46:42

There are a a number of different indicator dyes you could use (http://www.make-biodiesel.org/Biodiesel-Chemistry/ph-indicating-dyes-for-biodiesel.html).

I would think you would choose a fairly dilute indicator solution so that the indicator doesn't influence the actual solution.  However, the exact concentration shouldn't be that vital, other than the intensity of your colors.

If you could get a couple of pH test strips, you could make your own color charts and standards.