Separation of barium from alkaline earths and associated elements by extraction with dibenzo-18-crown-6 from a picrate medium

Barium is extracted quantitatively at pH 3–9 with 1 × 10^?2 M dibenzo-18-crown-6 into nitrobenzene from solutions containing 1 × 10^?2 M picric acid, stripped with 1 M nitric acid and determined spectrophotometrically at 640 nm as its complex with sulfonazo-III. Barium can be separated from alkali and other alkaline earth elements and from lead, manganese, chromium, zinc and mercury. The halides, oxyanions and anions of organic acids are tolerated. The method is applied to the determination of barium in barium meal, barite and witherite.