Methanol cannot dissolve salt or loosen the sodium cation/chloride anion from the NaCL ionic bond. -only water with high solvent power and high dielectric constant can do this. NaCL crystal is extremely strong and rigid. A Sodium ion is equally attracted to 6 Chloride ions.

To this 80cc mixture--- add 1/2 cc silver nitrate( High strength 10%, Increase receiprocal solution strength) plus 2cc nitric acid ( strength 20%) plus 17.5 cc di water to make 100 cc total.
Shake and stand for 5 minutes. Compare milkiness with a standard comparator of 1ppm made as follows:
50cc Methanol + 4cc standard Chloride soln ( strength 10ppm ) + 1/2 cc Silver Nitrate ( strength 10%) + 2cc Nitric acid ( strength 20%) + 43.5 cc DI water to make total 100cc solution . Memorise this milkiness as the failing standard for the current voyage.
(for 0.5 ppm comparator put 2 cc of standard chloride soln, for 0.250 ppm put 1 CC.) For 2 ppm put 8cc NaCl ----for 4ppm put 16cc NaCl.