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micrograms per liter to parts per billion

micrograms per liter to parts per billion
by BSea on 03/04/04 at 00:45:47

This relates to the concentration of (TCE)Trichloroethene found in groundwater test wells near my house. The guilty company was allowed to "monitor" itself by the EPA. They publish their results in micrograms per liter. The standard reporting requirement is to publish data in (ppm)parts per million, (ppb)parts per billion, or milligrams per liter. How can I convert micrograms per liter to the other three to find out how fast they are poisoning me? Thanks in advance, this site is a life saver (literally, lol )

Re: micrograms per liter to parts per billion
by Robert Fogt on 03/04/04 at 14:04:14

While you can easily convert between micrograms/liter and milligrams/liter, and between PPM and PPB, its not so easy to convert between the different types of units such as milligrams/liter to PPM.

To convert micrograms per liter to milligrams per liter, divide by 1000.

To convert to PPM, you would first need to know the density of the substance, and the density of what the substance is in. In your case, TCE, and water.  I know the density of water, just need to find out the density of TCE.

Re: micrograms per liter to parts per billion
by BSea on 03/05/04 at 00:22:29

Thanks for  the quick reply, this is a great site.
OK, I found a site that hopefully has the info on TCE.

Density (at 20 degrees C)    1.465 g/mL

Solubility (Water at 20 degrees C)   1.070 g/L
              (Water at 25 degrees C)   1.366 g/L

Conversion factors
              Water    1ppm (weight per volume)= 1 mg/L

Ok, so here is my goal:
The EPA set the maximum contaminant limit for TCE in drinking water at  0.005 milligrams per liter (0.005 mg/L) or 5 parts of TCE per billion parts water.

The readings reported by the company at the groundwater test well next to my house:

In 2002        3.1 micrograms per liter

In 2003        20  micrograms per liter

I am trying to convert this info reported  by the company into the EPA required method of reporting (which obviously the company did not do) so I can understand the level of contamination by these experts of deception that are dumping hazardous waste that flows into the drainage ditch behind my backyard fence.

Thanks again for  the help. I have been searching for this conversion for over a year!

Re: micrograms per liter to parts per billion
by Robert Fogt on 03/05/04 at 01:28:34

That makes things easier, you found the conversion factor you needed.
1 mg/L = 1 PPM
1 ug/L = 1 PPB

3.1 ug/L / 1000 = 0.0031 mg/L

That is 3.1 PPB which is below the maximum.

20 ug/L / 1000 = 0.02 mg/L

That is 20 PPB which is way above the maximum.  4 times the maximum allowed.

Anything over 5 micrograms/liter is too much.

Re: micrograms per liter to parts per billion
by Albert on 03/07/04 at 01:51:27

Robert's first post is not completely correct!

Lets look at the basics first:

Formal definition of PPM is mg per Kg of substance
(10^-6 : mg/kg= 10^-6 = factor million)
Or for PPB: microgram per Kg substance (10^-9)

Since we know that 1 Kg water is 1 liter we can say that for waterous dilutions of an substance PPM is mg per liter. This is OK as long as the density of the waterous solution does not significantly deviates from 1.00 Kg per liter.

If the density is not 1.00 Kg/l we should say PPM is mg/Kg

Substances in trace amounts (PPM, PPB level) does not have a significant influence on the density of the solution.

OK the conversion from PPM to PPB is just a factor 1000 (10^-6 to 10^-9)

So that is easy!

1 PPM = 1000 PPB = 1000 000 PPT
mg/kg = microg/Kg = nanog/Kg

Hope this clarifies the matter a bit.


Re: micrograms per liter to parts per billion
by BSea on 03/12/04 at 22:59:08

Hey Albert (and Robert),
Thanks again for all the help. I am absolutely clear on one thing......I sure wish I sat next to you or Robert back in my Chemistry and Math classes during my college years!! lol

Just to make sure, I would like a follow-up from one or both of you after your post, Albert. Do we all agree that  the reply # 3 from Robert on March 5th is correct? I am assuming we all agree on that part, right?  

Thanks again, this site is a great resource.

Re: micrograms per liter to parts per billion
by Robert Fogt on 03/13/04 at 10:53:49

What Albert is saying is that my post was correct, only if the substance has the same density of the substance it is disolved in, water.

It doesn't, but it is very close, and the amounts are so small that it wont effect the density of the water solution. Think of 3.1 PPB as 3.1 parts solution to 1 billion parts water.  The amount of the solution is so small it will not effect it in any measurable amount.

Re: micrograms per liter to parts per billion
by Albert on 03/16/04 at 05:03:22

There were two points of Robberts first reply i wanted to address:

1 st: he said it was not easy to covert mg/L to PPM
In my opinion this is not difficult at all (see my explanation in my previous mail.

You don't need to know the density of TCE
If the concentration is in PPM level the density of TCE does not significantly alters the density of water (sample).
As TCE is given in mg: mg/L <> mg/Kg

If we would have for instance a sample seawater and want to express the TCE content in PPM we have to define PPM TCE as mg per Kg (formal definition of PPM) of sea water, since the density of seawater is significantly higher as 1.000 Kg/L


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