Chromatography Forum

Hi.. i have a stupid prolbem!

Why Standard Solution is 5 ppm?

Limit spec is 200 ppm!

https://ibb.co/f2wBGPZ

because it doesn't rely on concentrations but mass of chlorides.

mass of sample in test solution tube: 10 g/100 ml *2.5 ml = 250 mg (of sample)
mass of chloride in standard solution tube: 10 ml * 5 mg [Cl]-/L = 50 µg of Cl-

50 µg/250 mg = 0.200 µg/mg = 200 ppm

because it doesn't rely on concentrations but mass of chlorides.

mass of sample in test solution tube: 10 g/100 ml *2.5 ml = 250 mg (of sample)
mass of chloride in standard solution tube: 10 ml * 5 mg [Cl]-/L = 50 µg of Cl-

50 µg/250 mg = 0.200 µg/mg = 200 ppm

okkk thanks.. but.... why 50/250? or why a fraction and not an equivalence?

okkk thanks.. but.... why 50/250? or why a fraction and not an equivalence?

Don't know exactly what you mean.

50 µg of [Cl]- give a certain turbidity.
if the same turbidity is observed in your test solution, then you would have 50 µg [Cl]- in 250 mg of your sample, which is an amount of 200 ppm.

The test states that the turbidity is less than that of 50 µg of [Cl]-, so your amount is < 200 ppm


The test should also work if you take 1 ml of a 50 ppm standard and add 14 ml of water, or 5 ml of a 10 ppm plus 10 ml of water, and so on.
Goal is to have 50 µg of chlorine-ions in 15 ml of solution before adding the nitric acid and silver nitrate.