Synonyms

Potassium sodium L-(+)-tartrate

Rochelle salt

Seignette salt

Definition

Chemical name

Potassium sodium salt of L-2,3-dihydroxybutanedioic acid

Potassium sodium L-(+)-tartrate

Einecs

206-156-8

Chemical formula

C₄H₄O₆KNa· 4H₂O

Molecular weight

282,23

Assay

Content not less than 99 % on the anhydrous basis

Description

Colourless crystals or white crystalline powder

Identification

1 gram is soluble in 1 ml of water, insoluble in ethanol

Between 70 and 80 ^oC

Purity

Loss on drying

Not more than 26,0 % and not less than 21,0 % determined by drying at 150 ^oC for three hours

Oxalates

Not more than 100 mg/kg expressed as oxalic acid, after drying

pH of 1 % aqueous solution

Between 6,5 and 8,5

Arsenic

Not more than 3 mg/kg

Lead

Not more than 5 mg/kg

Mercury

Not more than 1 mg/kg

Heavy metals (as Pb)

Not more than 10 mg/kg