I get that hydrogen peroxide comes in varying concentrations, with 3%, 15-18%, 30-35% and 50% being most common. But in addition to the concentrations, there is often a “grade” stated on the bottle such as “food grade” or “lab grade”.
What does the grade tell me that the concentration percentage doesn’t? What’s the diff between 30% H[sub]2[/sub]O[sub]2[/sub] and 30% food grade H[sub]2[/sub]O[sub]2[/sub]?
I’d imagine it’s tied back to shelf life. Peroxide is looking to breakdown into OH radicals so stabilizers are introduced to extend the product’s life. Food Grade would mean that it meets whatever national code exists and likely doesn’t include the stabilizers in other grades.
“Food grade” is a term applied to concentrated H202 products that are approved to disinfect food processing equipment.
Unfortunately, there are quite a few dumb/deluded people who think concentrated H202 is a cure for various diseases, and that “food grade” means “safe to drink and/or bathe in”.
Actually it’s quite toxic unless profoundly diluted, and fatalities have resulted.
I can’t say for peroxide specifically, but for a lot of chemicals the difference is in the trace contaminants. Some contaminants might be OK for one industrial process, not OK for another, and would be outright toxic in food. Ethanol, for example, can be distilled with benzene to get concentrations higher than 95% (though I understand modern methods use molecular sieves instead). The residual benzene is almost never a problem for the lab applications I’m familiar with, but it would be a horrible idea to drink the stuff in any quantity.
H2O2 will degrade rapidly without stabilizers added to it. Food grade should be pure H2O2.
When I was at university we “acquired” big lab bottles of ethanol to make cocktails. We had to be sure to get the HPLC-grade stuff, as that didn’t have benzene in it.
When I was at university we “acquired” big lab bottles of ethanol to make cocktails. We had to be sure to get the HPLC-grade stuff, as that didn’t have benzene in it.
(Of course, we could have just used the normal 95% stuff, but we wanted it neat, dammit!)
Well, I know I’d never drink any hydrogen peroxide which wasn’t food grade!
Two chemists walk into a bar. The first one says, “Give me some H2O.” The second one says, “I’ll have some H2O, too.” Then he died.
Food grade means its made safely so that it doesn’t contain anything nasty… Every thing along the way is food grade, the input, the machinery, the storage containers.
On the other hand, Lab grade could be stored in containers or processed on equipment , or made from ingredients that have lead, cadmium , arsenic , mercury … they may be very low level in the industrial grade, but they are cumulative poisons …
Thanks. I ended up getting 35% but there is no mention of any grade on the label. This is only for the ‘elephant’s toothpaste’ demo, so trace contaminants shouldn’t be a big deal.
Not pure H[sub]2[/sub]O[sub]2[/sub]; water is also present, of course. (To a chemist, the term “pure H[sub]2[/sub]O[sub]2[/sub]” means only that particular chemical species is present, that is 100% H[sub]2[/sub]O[sub]2[/sub].)
“Food grade” hydrogen peroxide is typically sold as 35% H[sub]2[/sub]O[sub]2[/sub], with the remainder consisting of water. A solution of 35% H[sub]2[/sub]O[sub]2[/sub] is still quite concentrated; note that the typical percentage of hydrogen peroxide for antiseptic use is more like 3%.
As others have noted, pure H[sub]2[/sub]O[sub]2[/sub] is exceedingly dangerous. This was discussed in a thread a few years ago, in which I stated: