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Topic: CAS # How specific or how general is this I.D.#?  (Read 7521 times)

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Offline Smokin

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CAS # How specific or how general is this I.D.#?
« on: April 07, 2008, 06:35:36 PM »
Ive been more and more interested in chemistry and looking into my pigments and how&why it performs the way it does. Ive been looking up Cas#s alot to see what was in a certain product or whatever. My question is, how reliable is a CAS#?

I believe that CAS#s are both general and specific. THat a number can represent mineral oil, or a mineral oil from a specific plant.

Here is a specific scenario as to why I ask. Im am buying lead carbonate here:
http://sargentwelch.com/product.asp?pn=WLC94159-04_EA&ss=WLC94159-06

I can buy a more expensive lead at an art store, but it has the exact same CAS#. I know lead carbonate can be processed in many ways and develope many shapes and forms, ... but if they share the same cas# like this, is it safe to assume they are the exact same thing? Would love to hear input on this.

Offline Arkcon

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Re: CAS # How specific or how general is this I.D.#?
« Reply #1 on: April 07, 2008, 07:22:24 PM »
The CAS# is assigned to anyone who asks for one, it can be assigned to any chemical, a compound, a mixture, or even a compound or mixture that you want to keep a trade secret and not divulge the composition of.  It allows a bottle to be labeled with a unique identifier, that can then be linked, electronically or on paper, to an MSDS. 

If the CAS# is the same, it is exactly the same product, but the same product from two separate manufactures, or for two different uses, may have different CAS#'s. 

Nothing in the CAS# is meant to give you a hint about the composition of the substance, there's no pattern to the names and numbers.  However, CAS#'s do have an internal pattern, the last digit is a modulo checksum, so you can tell at a glance (or at least a computer can) if the number is wrong.

The state of New Jersey is one municipality that requires the CAS# on any bottle stored anywhere in an industrial setting.  You can label it in English or some foreign language, you can label it with the formula, or call it reagent X23/J5, but none of those count, only the CAS# does.  I'm so glad I don't work there anymore -- you ever try to get five (you only have to include the top five components) labels on a 1.5 mL tube?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Smokin

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Re: CAS # How specific or how general is this I.D.#?
« Reply #2 on: April 08, 2008, 04:29:20 AM »
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you ever try to get five (you only have to include the top five components) labels on a 1.5 mL tube?
lol  :D

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If the CAS# is the same, it is exactly the same product, but the same product from two separate manufactures, or for two different uses, may have different CAS#'s.

Thank you so much for the response. Just to double check then. If a product's MSDS sheet lists a CAS number for say Turpintine, we may not know where the turpintine came from exactly, from a tree, petrolium, or whatever species, but is it safe to assume that any other product that lists the same Cas# is using the exact same turpintine, or is it possible that one product is using one type of turp from another source and just using a "generic CAS #"?

Offline sjb

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Re: CAS # How specific or how general is this I.D.#?
« Reply #3 on: April 08, 2008, 05:02:30 AM »
As far as I know, turpentine is not just one substance, or even a precise mix of substances. So it's likely that the CAS RN you have for it is just for generic turpentine IMO.

In a similar way, white phosphorus and red phosphorus have different CAS RN, but phosphorus in general whould have a third set, I think.

An analogy might be a bit like whisky being a generic term, and things like Auchentoshan or Laphraoig being subcategories, even though neither single malt is a pure substance in the chemical sense.

Offline sjb

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Re: CAS # How specific or how general is this I.D.#?
« Reply #4 on: April 08, 2008, 05:07:48 AM »
The state of New Jersey is one municipality that requires the CAS# on any bottle stored anywhere in an industrial setting.  You can label it in English or some foreign language, you can label it with the formula, or call it reagent X23/J5, but none of those count, only the CAS# does.  I'm so glad I don't work there anymore -- you ever try to get five (you only have to include the top five components) labels on a 1.5 mL tube?

Any bottle? That must cause chaos at Merck or similar. Or can you get away with "well, I stuck foo-bah acyl chloride and yakety amine in there" without saying you ought to have the amide by now. What about all the intermediates that aren't commercial? Do they have T1 or similar straight to Columbus, OH for instant access CAS-RN allocation?

S

Offline Arkcon

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Re: CAS # How specific or how general is this I.D.#?
« Reply #5 on: April 08, 2008, 08:06:09 AM »
Any bottle? That must cause chaos at Merck or similar. Or can you get away with "well, I stuck foo-bah acyl chloride and yakety amine in there" without saying you ought to have the amide by now.

Exactly.  First off, commercial sources always have the CAS# on the label, in addition to multiple names, IUPAC, and common name, in various languages.  Your second point is more provocative, in a related task, I've been tasked with labeling my titration waste.  Logically, it should be labeled with the products, but legally, they want what goes in, listed.

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What about all the intermediates that aren't commercial? Do they have T1 or similar straight to Columbus, OH for instant access CAS-RN allocation?

You can label something with CAS# - unavailable.  The New Jersey statute is all about their way of implementing the end-user's "right-to-know."  To keep the company from hiding the identity of what their chemists, line workers, and janitors are working with.

It was so weird back where I was working.  We had to label each tube, and they were just beginning the implementation as I was leaving.  Our products were synthetic biomolecules (oligonucleotides.)  It was going to be a system of stick on colored dots, cross referenced to a page taped to the refrigerator -- which was stupid enough (those gummed dots were going to fall off with condensation).

The top component was water, then buffer component acid, and base, then the titrating base to adjust pH -- sodium hydroxide, then, oligo -- which had an unknown CAS#.  And that's it -- different oligos, but the same CAS label.  But -- ah -- we were in production -- before it was finalized, it might be in plain water, or just buffer, or in NaOH solution, or ... with a tag for each.

For another product, there was another mixture, with water, a different buffer, KOH (yep, you list it like you make it, and ignore the KOH is really gone, and the buffer has been titrated to a mix of acid and base), and a supporting salt, and EDTA -- opps, that's 5 components, no need to list the oligo, or the preservative -- the only really hazardous component --sodium azide.  ::)

There's a whole group of people in charge of this sort of thing.  In a way, they're proud to be part of the team, keeping the rest of us safe.  But sometimes, it seems to me, they're just there to get in the way.  How does everyone else feel about this stuff.

Shoulda started a new thread.  Oh well, I don't work in NJ anymore, anyway.
« Last Edit: April 08, 2008, 12:40:07 PM by Arkcon »
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Arkcon

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Re: CAS # How specific or how general is this I.D.#?
« Reply #6 on: April 08, 2008, 12:51:09 PM »
or is it possible that one product is using one type of turp from another source and just using a "generic CAS #"?

This particular situation here I've quoted from you here, yes, is perfectly allowable.  If some company has the petroleum turp CAS# and another one has a pine tar distilled turp CAS# and third party can use either one, if they feel like it.  They're only doing it as a courtesy for the end user to help them look it up, or because the local municipality requires it, or something like that.

My first introduction to the CAS#'s was way back in 1990.  The bottle of anti-static spray from Radio Shack listed it's ingredients by CAS#, and nothing else.  Perhaps as a crude way of listing ingredients, without helping home users to mix their own.  I asked the boss what these numbers meant, and he didn't even know.  Probably was just blind compliance for municipalities that required it, maybe California too?  Were they doing that way back when?  They always seemed pretty progressive at screwing businesses over. ::)
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

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