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Topic: Units of ppb  (Read 26835 times)

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Offline CopperSmurf

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Units of ppb
« on: April 06, 2008, 12:14:19 AM »
Hi. I've 2 quick yes/no questions with units after trying to work them out:

is ppb (parts per billion) exactly the same as ng/mL (nanograms per millilitre)?

and can ppm (parts per million) be the same as micrograms / mL ?

Thanks for any yes/no replies :P

Offline Alpha-Omega

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Re: Units of ppb
« Reply #1 on: April 06, 2008, 01:08:43 AM »
For ppm (the same approach can be followed for ppb)

1000 g = 1 kg

1000 mg = 1 g

1 mg/L = 1 ppm

1000 mg/g

1000kg/L

1kg/L

and 1 kg = 1 L

so 1 mg/L = 1 ppm

.01% = 1 ppm

1% = 100 ppm

Generally:

ppm = parts per million

grams/milliliter = g/ml = milligrams/microliter = mg/ul

1ug /ml = 1mg/l = 1ppm

ppm = ug/g =ug/ml = ng/mg = pg/ug = 10-6

ppm = mg/liter of water

1 g / 1000ml = 1000 ppm

PPB = Parts per billion = ng/g = ng/ml = pg/mg = 10-9

Please note my notation says-IN WATER.  So for clarification purposes:
:
Parts Per Million. (ppm)

Concentration expressed as parts of solute per million parts of solution. Usually refers to parts per million by mass. For example, a 10 ppm NaCl solution can be written as: 10 mg NaCl/kg solution, 10 µg NaCl/g solution, 10 ng NaCl/mg solution. In very dilute aqueous solutions, ppm is approximately equal to mg solute per liter of solution.

Parts Per Billion (ppb)

Definition:
A weight to weight ratio used to describe concentrations. Parts per billion (ppb) is the number of units of mass of a contaminant per 1000 million units of total mass.
Also µg/L or micrograms per liter.

ppb (or ppbm) is used to measure the concentration of a contaminant in soils and sediments. In that case 1 ppb equals 1 µg of substance per kg of solid (µg/kg).
ppb (or ppbm) is also sometimes used to describe small concentrations in water, in which case 1 ppb is equivalent to 1 µg/l because a liter of water weighs approximately a 1000 000 µg. This use of ppb tends to be phased out in favour of µg/l.

ppb (or ppbV) is often used to describe concentrations of contaminants in air (as a volume fraction). In this case the conversion of ppb to µg/m3 depends on the molecular weight of the contaminant.
For example, 1 ppb chlorine represents one part of chlorine in one thousand million parts of air by weight, which is 1.45 µg/m3.

References:

http://antoine.frostburg.edu/chem/senese/101/glossary/p.shtml

http://en.wikipedia.org/wiki/Parts_per_million



« Last Edit: April 06, 2008, 06:59:38 AM by Alpha-Omega »

Online Borek

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Re: Units of ppb
« Reply #2 on: April 06, 2008, 05:12:44 AM »
1 mg/L = 1 ppm

So how come 1 mg of substance dissolved in 1L of methanol is 1.26 ppm?
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Offline Alpha-Omega

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Re: Units of ppb
« Reply #3 on: April 06, 2008, 06:55:32 AM »
I believe my notation says "IN WATER".  But since you want a full explanation.  No one ever asks for this when dooing conversions.  I do believe this is a first. Have to tag this one..

Parts Per Million. (ppm)

Concentration expressed as parts of solute per million parts of solution. Usually refers to parts per million by mass. For example, a 10 ppm NaCl solution can be written as: 10 mg NaCl/kg solution, 10 µg NaCl/g solution, 10 ng NaCl/mg solution. In very dilute aqueous solutions, ppm is approximately equal to mg solute per liter of solution.

Parts Per Billion (ppb)

Definition:
A weight to weight ratio used to describe concentrations. Parts per billion (ppb) is the number of units of mass of a contaminant per 1000 million units of total mass.
Also µg/L or micrograms per liter.

ppb (or ppbm) is used to measure the concentration of a contaminant in soils and sediments. In that case 1 ppb equals 1 µg of substance per kg of solid (µg/kg).

ppb (or ppbm) is also sometimes used to describe small concentrations in water, in which case 1 ppb is equivalent to 1 µg/l because a liter of water weighs approximately a 1000 000 µg. This use of ppb tends to be phased out in favour of µg/l.

ppb (or ppbV) is often used to describe concentrations of contaminants in air (as a volume fraction). In this case the conversion of ppb to µg/m3 depends on the molecular weight of the contaminant.
For example, 1 ppb chlorine represents one part of chlorine in one thousand million parts of air by weight, which is 1.45 µg/m3.

References:

http://antoine.frostburg.edu/chem/senese/101/glossary/p.shtml

http://en.wikipedia.org/wiki/Parts_per_million

That should cover it!!!!!!  ;D


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Re: Units of ppb
« Reply #4 on: April 06, 2008, 08:03:28 AM »
I believe my notation says "IN WATER".

What I am aiming at is that ppx notation - similarly as percentages - needs clarification when used. It can be w/w, it can be v/v, it can be atoms/atoms or molecules/molecules and so on, in each case numbers are slightly different. As there is no one and only one correct approach ppx can be occasionally confusing.
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Offline Alpha-Omega

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Re: Units of ppb
« Reply #5 on: April 06, 2008, 08:09:41 AM »
AIM AT THIS....

http://www.chemicalforums.com/index.php?topic=25113.0

OH and BTW....you have not done this on any of the other 1,000,000 posts on ppm and ppb...I believe I answered the question accuratly.

Online Borek

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Re: Units of ppb
« Reply #6 on: April 06, 2008, 08:38:23 AM »
AIM AT THIS....

http://www.chemicalforums.com/index.php?topic=25113.0

Conversion of one type of ppm to other type of ppm - when both are well defined - is not ambiguous.

OH and BTW....you have not done this on any of the other 1,000,000 posts on ppm and ppb...

This topic has been discussed previusly on several occasions:

http://www.chemicalforums.com/index.php?topic=25068.msg94754#msg94754

http://www.chemicalforums.com/index.php?topic=23772.msg90293#msg90293

http://www.chemicalforums.com/index.php?topic=21170.msg80324#msg80324

and so on.

There was no mention of "in water" in the original text of your post, please stop editing your posts to change their meaning.
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Offline Alpha-Omega

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Re: Units of ppb
« Reply #7 on: April 06, 2008, 08:52:50 AM »
Back Up What You Profess-AIM AT THIS:

AIM AT THIS....

http://www.chemicalforums.com/index.php?topic=25113.0

I see a full complete answer with wrong formulae.....Mr. MODERATOR of the Analytical Forum...where is all the hellfire now...all the scathing remarks and inuendo....where is it???  Arent yougoing to take care of that!!!!!!!

Yes your contradictions...getting tired..

Take few more because this is so worth it!!!!!!!!!!

So you have 2 sets of rules one for me...and one for...whoever...RIGHT!!!!!!!!  And your response to my response to that question above makes NO SENSE!!!!!!!

My notation is just fine..

Offline CopperSmurf

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Re: Units of ppb
« Reply #8 on: April 06, 2008, 11:11:37 AM »
I didn't really expect so much of a debate over this. Sorry but I did forget to mention that I'm assuming all of the concentrations are dissolved in water.

And my professor did say that because the concentrations are in water, assume that 1 g = 1 mL, so it is actually an approximation when volumes are used.

Thanks so much for the ppm & ppb help guys!  :D

Offline Mitch

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Re: Units of ppb
« Reply #9 on: April 07, 2008, 12:36:32 AM »
topic locked. Cool down guys.
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