Wednesday, March 08, 2006

this one's for the scientists 

This morning I found myself in the unfortunate position of having to make some 10% SDS stock.

Yeah, *groan* is right. Making SDS sucks. If you're not wearing a mask, the power goes into your lungs and make you cough, and once you get it into water, it NEVER wants to go into solution. You have to make sure the water is hot, and then get the pH just right, and it's really just a big pain in the ass.

So I got a beaker of water heating up on the hot plate, and i measure out the SDS, and when the water hits about 60 C, I add the powder. Ideally, the temp should be 68 C, but I figure I'll just let it stir for awhile while I go about my business.

5 minutes, later, the solution was clear. It had all..gone...into solution. Without being the proper temperature OR adding HCl to bring down the pH.

I was happy, but suscpicious.

I pH'ed it. It was around 5. It's supposed to be 7.2 or most likely higher, as the HCl is used to bring DOWN the pH. It's not supposed to be 5!

There are only two components...SDS and water. I tested the filtered water.

pH of 4.2.

Ohhhh...that's not good. All our water is acidic. Even the tap water is around 5.5 What the hell? Why has no one noticed this??? How long has it been this way?? How much of our work has been affected?


Seriously, it's ALWAYS our lab. A few years ago, one of the water heaters broke. We were without hot water in the lab for weeks. Finally, we complained, and they discovered the broken heater. But there are 30 or so other labs in this building that it affected, not a ONE of them complained, or even noticed.

Anyway...I got my solution to the proper pH with a couple drops of NaOH...then I remembered that once I got it pH'ed, I had to bring the volume up to 1 liter...which with our acidic water of DOOM would fuck up the pH again.


AND I'm making another, more critical buffer today, too. You know, I go MONTHS at a time without making any of this shit. YEARS sometimes. Now that our water is more acidic than ACID RAIN...I'm in pH hell.

anyway...thus ends the science rant for today.