Parts per million Conversions

Parts per million Conversions


PPM conversion values and serial dilutions : How to dilute and calculate ppm concentrations
and volumes, and how to convert ppm to molarity and percentage amounts.


ppm = parts per million

ppm is a term used in chemistry to denote a very, very low concentration of a solution. One gram in 1000 ml is 1000 ppm and one thousandth of a gram (0.001g) in 1000 ml is one ppm.

One thousanth of a gram is one milligram and 1000 ml is one liter, so that 1 ppm = 1 mg per liter = mg/Liter.
ppm is derived from the fact that the density of water is taken as 1kg/L = 1,000,000 mg/L, and 1mg/L is 1mg/1,000,000mg or one part in one million.

OBSERVE THE FOLLOWING UNITS

1 ppm = 1mg/l = 1ug /ml = 1000ug/L
ppm = ug/g =ug/ml = ng/mg = pg/ug = 10 -6
ppm = mg/litres of water

1 gram pure element disolved in 1000ml = 1000 ppm

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


Making up 1000 ppm solutions

1. From the pure metal : weigh out accurately 1.000g of metal, dissolve in 1 : 1 conc. nitric or hydrochloric acid, and make up to the mark in 1 liter volume deionised water.

2. From a salt of the metal :
e.g. Make a 1000 ppm standard of Na using the salt NaCl.

FW of salt = 58.44g.
At. wt. of Na = 23
1g Na in relation to FW of salt = 58.44 / 23 = 2.542g.
Hence, weigh out 2.542g NaCl and dissolve in 1 liter volume to make a 1000 ppm Na standard.

3. From an acidic radical of the salt :
e.g. Make a 1000 ppm phosphate standard using the salt KH2PO4

FW of salt = 136.09
FW of radical PO4 = 95
1g PO4 in relation to FW of salt = 136.09 / 95 = 1.432g.
Hence, weigh out 1.432g KH2PO4 and dissolve in 1 liter volume to make a 1000 ppm PO4 standard.



Dilution Formula = M1V1 = M2V2

req is the required value you want.

req ppm x req vol
-------------------------- = no of mls for req vol
stock

e.g. Make up 50 mls vol of 25 ppm from 100 ppm

25 x 50 / 100 = 12.5 mls. i.e. 12.5 mls of 100 ppm in 50 ml volume will give a 25 ppm solution


Serial dilutions


Making up 10-1 M to 10-5 M solutions from a 1M stock solution.

Pipette 10 ml of the 1M stock into a 100 ml volumetric flask and make up to the mark to give a 10-1 M soln.
Now, pipette 10 ml of this 10-1 M soln. into another 100 ml flask and make up to the mark to give a 10-2 M soln.
Pipette again, 10 ml of this 10-2 M soln. into yet another 100 ml flask and make up to mark to give a 10-3 M soln.
Pipette a 10 ml of this 10-3 M soln. into another 100 ml flask and make up to mark to give a 10-4 M soln.
And from this 10-4 M soln. pipette 10 ml into a 100 ml flask and make up to mark to give a final 10-5 M solution.


Molarity to ppm


conc. in mg/l
Molarity = ------------------------
gram mol solute x 1000

Example : What is the Molarity of Ca in a 400 ppm solution of CaCO3.
Solute = 1 gram mole Ca = 40 (At. Wt.) = 40g/liter = 40 x 1000 = 40,000 mg/liter = 40,000 ppm.
Solution = 400ppm (given)
Hence Molarity = 400 divided by 40000 = 0.01M
And ppm is 0.01 x 40 x 1000 = 400 ppm.(cross multiply)

The FW of an ion species is equal to its concentration in ppm at 10-3M. Fluoride has a FW of 19, hence a 10-3M concentration is equal to 19ppm, 1M is equal to 19,000 ppm and 1ppm is equal to 5.2 x 10-5M.

ISE molarity/ppm conversions


Ppm (parts per million) to % (parts per hundred)


Example:


1 ppm = 1/1,000,000 = 0.000001 = 0.0001%
10 ppm = 10/1,000,000 = 0.00001 = 0.001%
100 ppm = 100/1,000,000 = 0.0001 = 0.01%
200 ppn = 200/1,000,000 = 0.0002 = 0.02%
5000 ppm = 5000/1,000,000 = 0.005 = 0.5%
10,000 ppm = 10000/1,000,000 = 0.01 = 1.0%
20,000 ppm = 20000/1,000,000 = 0.02 = 2.0%

(Parts per hundred) % to ppm

Example:


0.01% = 0.0001
0.0001 x 1,000,000 = 100 ppm


Ppm (parts per million) to % (parts per hundred)


Example:


1 ppm = 1/1,000,000 = 0.000001 = 0.0001%
10 ppm = 10/1,000,000 = 0.00001 = 0.001%
100 ppm = 100/1,000,000 = 0.0001 = 0.01%
200 ppn = 200/1,000,000 = 0.0002 = 0.02%
5000 ppm = 5000/1,000,000 = 0.005 = 0.5%
10,000 ppm = 10000/1,000,000 = 0.01 = 1.0%
20,000 ppm = 20000/1,000,000 = 0.02 = 2.0%