mg/L to ppm

I am trying to convert a test result that is provided as mg/L to ppm. The specification requirement is 600 ppm (parts per million) and my test result is shown as 711 mg/L. If remember correctly the conversion is equivalent but I am not sure.

[Robert Fogt]

Many resources you find show mg/L the same as ppm, but its not exactly true.

Pure water at standard temperature and pressure has a density of 1 kg/L, therefore:

mg/L = mg/kg = ppm

But that is only true when using pure water at standard temperature and pressure. Any other substance will have a different density and will not be a direct conversion between mg/L and ppm.

[Mrs X]

Hi, for a solid-solid system, the conversion for ppm is mg/kg. For a solid-liquid system, the conversion is mg/L. For a gas-gas system, the conversion is uL/L.

In a solid-liquid system you can calculate proportions easily, using dilution factors etc. As the liquid is effectively just a carrier, the density of the liquid is not usually important.

In your system, 711mg/L is 711ppm, if it was measured at room temperature, or at some other specified temperature of interest.

i have a small conversion to make can you help to sort it out.

i am adding 80 grams of color in one litre water and out of this i am using 50 ml to 40 kg mass

i am adding 60 grams of color in 600 ml of water and out of this i aming using 4 ml to 40 kg same mass mentioned above.


can you calculate and tell the total ppm of color in this 40 kg mass

[Mrs X]

Originally Posted by Unregistered

i have a small conversion to make can you help to sort it out.

i am adding 80 grams of color in one litre water and out of this i am using 50 ml to 40 kg mass

i am adding 60 grams of color in 600 ml of water and out of this i aming using 4 ml to 40 kg same mass mentioned above.


can you calculate and tell the total ppm of color in this 40 kg mass

This sounds like a home work question - I don't give answers for these, but will help you to work it out for yourself.

For your first one, you are taking 50mL/1000mL x 80g. = weight A.

Weight A x1000 = mg of weight A.

this weight A (in mg) is going in to 40kg.

Now work out how many mg of A is in each kg. That is your answer. (mg/kg = ppm)

Have a go at the second one yourself. You are welcome to post back here if you would like your answers checked. Good luck with your studies.

Hai there im sorry but i am confused with your reply please see if i got it right

I take 20 ml from a solution of 2.19g/100 ml so inorder to convert it to ppm 0r mg/kg

it would be 20ml/(100ml*2.19gm) = 91.324 mg

please do help me out as i cant find the answers to this any were else !

[Mrs X]

Originally Posted by fuzik

Hai there im sorry but i am confused with your reply please see if i got it right

I take 20 ml from a solution of 2.19g/100 ml so inorder to convert it to ppm 0r mg/kg

it would be 20ml/(100ml*2.19gm) = 91.324 mg

please do help me out as i cant find the answers to this any were else !

Just making sure i understand what you are asking, you are taking 20mLof a solution, and you want to know what weight of the compound of interest you have?

In 100mL you have 2.19g, in 20mL you have 20/100 of that.

2.19g x (20/100) = 0.438g, or 438mg

These are proportion calculations, so always work out what proportion you are taking. - In this case a fifth. Hope this helps, and good luck with your studies.

Honestly thank you very much i get it finally!

Okay i am sorry to bother you again its jut my supervisor is on a holiday

If i took .005 litres (5 mL) from a standard solution of 21900mg/1litre

Here 21900mg/1litre = 21900 ppm

but if i take out .005 ml from this i have 109.5 mg in it

is 109.5mg/.005ml also = 109.5 ppm? I would really appreciate it , thank you!

[JohnS]

Originally Posted by Unregistered

Okay i am sorry to bother you again its jut my supervisor is on a holiday

If i took .005 litres (5 mL) from a standard solution of 21900mg/1litre

Here 21900mg/1litre = 21900 ppm

but if i take out .005 ml from this i have 109.5 mg in it

is 109.5mg/.005ml also = 109.5 ppm? I would really appreciate it , thank you!

I believe you took out 0.005 L or 5 mL, not 0.005 mL. In any case the ppm value is a ratio and will NOT change if you take some stock solution (unless you also dilute it). 109.5 mg/0.005 L = 21900 ppm.