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gdflp
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My understanding is that the MSDS is required to list composition, NOT purity. For example, if they sell technical grade acetone which contains 5%
water, but they don't add any water to the composition and the mixture simply contains it, then they can write 100% acetone. Similarly, the
thiophenes are an impurity which arises from the production of the toluene and they may exceed 1%, but since they are impurities and not ingredients
of the mixture they don't have to be listed on the MSDS. If they added 1% thiophenes to the mixture to improve some property of it though(this is
just an example, there's no reason to do this), then they would need to list 1% methylthiophene(or a concentration range) on the MSDS.
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JJay
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I think it depends on whether the impurity exists in a significant quantity to cause a safety issue. If a detergent has 0.05% mercury impurity, it had
better say so on the MSDS. On the other hand, if 2% sugar is added to it as an adhesive, it doesn't have to appear on the MSDS.
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CharlieA
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Here is a link to get the scoop on MSDS/SDS requirements:
https://www.osha.gov/Publications/OSHA3514.html
"Section 3: Composition/Information on Ingredients" starts out:
"This section identifies the ingredient(s) contained in the product indicated on the SDS, including impurities and stabilizing additives. This section
includes information on substances, mixtures, and all chemicals where a trade secret is claimed. The required information consists of...:
This is only a 6-page printout.
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Sniffity
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This might seem like a fairly stupid question D: But could you explain what's this "corrected to sea level" means? And why is this correction
necessary?
My way of understanding it was that the higher you take a barometre, the lower the pressure will be, and you didn't need to correct it? 
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Magpie
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Air traffic controllers obtain the local tower pressure using a barometer, which, as you say gives the true atmospheric pressure regardless of the
tower altitude. But this value is not usable by airplane pilots approaching the tower. They need a "corrected to sea level" value so they can dial
it in on their altimeters. Their altimeter will then read the correct altitude when they are at that given tower.
This is my understanding and is subject to correction by someone who actually knows - please.
The single most important condition for a successful synthesis is good mixing - Nicodem
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bobm4360
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An altimeter is just a barometer that reads funny. When you get tower pressure, and set that pressure in the altimeter, it will read field elevation
if you are on the ground at that airport, or field elevation plus your height above ground if you are in the air. Knowing your altitude above local
terrain is a Very Good Thing. Your altitude above sea level is worthless unless you are over the ocean.....
Above 18kft (mandatory instrument flight) everyone sets their altimeter to 29.92 in.Hg so they are on the same page and can maintain altitude
separation. If pilot A reads 19000 ft in his aircraft and pilot B reads 20000 ft in his, they will not have a close encounter of the worst kind. If
their altimeters were set at different fields, B could be at the same level as A or even below him.
The tower barometer is corrected for field elevation at standard temperature and pressure
[Edited on 12-11-2015 by bobm4360]
[Edited on 12-11-2015 by bobm4360]
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JJay
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Corrected to sea level means at a pressure of one atmosphere.
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Magpie
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I think I was incorrect in my explanation above about the "corrected to sea level" barometric pressure. This website gives the proper procedures:
http://www.skybrary.aero/index.php/Altimeter_Setting_Procedu...
Near the airfield the pilot wants to adjust his altimeter so that it reads his height (altitude) above the airfield (QFE).
The single most important condition for a successful synthesis is good mixing - Nicodem
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Texium
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To follow up, the KleanStrip toluene that I got at ACE seems to be very pure, as yesterday I synthesized tosylic acid with it and there was no
polymerization whatsoever. The solution became slightly yellow during the reaction, but the product precipitated on cooling as nearly pure white
crystals.
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Fyndium
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Barometric pressure gets me every time when I begin to suspect everything what I do when a distillation just keeps going over the limit even when
every single factor seems to be on point. Then, I remember to check the local weather station, do a little math and pieces fall together. Toluene
really keeps getting over at 113C when the barometer says 1020mbar.
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