Potassium Sulphate BP Ph Eur Grade

K2SO4 -- 174.3 -- 7778-80-5
Ph Eur

DEFINITION
Content: 98.5 per cent to 101.0 per cent of K2SO4 (dried substance).

CHARACTERS
Appearance: White or almost white, crystalline powder or colourless crystals.
Solubility: Soluble in water, practically insoluble in ethanol.

IDENTIFICATION
A. It gives the reactions of sulphates.
B. It gives the reactions of potassium.

TESTS
Solution S: Dissolve 10.0 g in 90 ml of carbon dioxide-free water prepared from distilled water,
heating gently. Allow to cool and dilute to 100 ml with carbon dioxide-free water prepared from distilled water.
Appearance of solution: Solution S is clear and colourless.
Acidity or alkalinity: To 10 ml of solution S add 0.1 ml of bromothymol blue solution R1. Not more than 0.5 ml of 0.01 M hydrochloric acid or 0.01 M sodium hydroxide is required to change the colour of the indicator.
Chlorides: Maximum 40 ppm.
Calcium: Maximum 200 ppm.
Iron: Maximum 10 ppm, determined on 10 ml of solution S.
Magnesium: Maximum 20 ppm.
Sodium: Maximum 0.10 per cent.
Heavy metals: Maximum 20 ppm.
Loss on drying: Maximum 1.0 per cent, determined on 1.000 g by drying in an oven at 130 °C for 4 h.

ASSAY
Dissolve 0.150 g in 40 ml of wate. Add 0.2 ml of 0.1 M hydrochloric acid and 80 ml of
methanol. Carry out a potentiometric titration, using 0.1 M lead nitrate and as
indicator electrode a lead-selective electrode and as reference electrode a silver-silver
chloride electrode.
1 ml of 0.1 M lead nitrate is equivalent to 17.43 mg of K2SO4.

Potassium Sulfate FCC Food Grade

K2SO4 Formula wt 174.26
INS: 515 CAS: [7778-80-5]

DESCRIPTION
Potassium Sulfate occurs as colorless or white crystals or as a crystalline powder. One gram dissolves in about 8.5 mL of water. It is insoluble in alcohol. The pH of a 1:20 aqueous solution is about 5.5 to 8.5.
Function: pH control.

REQUIREMENTS
Identification:A 1:10 aqueous solution gives positive tests for Potassium, Appendix IIIA.
Assay:Not less than 99.0% and not more than 100.5% of K2SO4.
Lead:Not more than 2 mg/kg.
Selenium: Not more than 5 mg/kg.

Potassium Sulfate Analytical Reagent Grade

K2SO4 ======= Formula Wt 174.26
CAS Number 7778-80-5

REQUIREMENTS
Assay: 99.0% K2SO4
pH of a 5% solution: 5.5-8.5 at 25C

MAXIMUM ALLOWABLE
Insoluble matter: 0.01%
Chloride (Cl): 0.001%
Nitrogen compounds (as N): 5 ppm
Heavy metals (as Pb): 5 ppm
Iron (Fe): 5 ppm
Calcium (Ca): 0.01%
Magnesium (Mg): 0.005%
Sodium (Na): 0.02%