Liquid-liquid extraction of osmium thiocyanate with hexamethylphosphoramide and direct spectrophotometric determination in the organic phase.
The use of hexamethylphosphoramide (HMPA) in the osmium-thiocyanate system makes the method more sensitive and selective. The blue colour formed by osmium(VIII) with thiocyanate in 1.5M hydrochloric acid is intensified in the presence of HMPA and the complex becomes readily extractable into chloroform. The colour system has its absorption maximum at 595 nm and obeys Beer's law over the range 0.5-16 mug of Os per ml. The optimum range is 2-10 mug/ml. The molar absorptivity is 2.09 x 10(4)l.mole(-1).cm(-1). The method is simple, sensitive and free from interference from many metal ions, including ruthenium and other platinum metals.
Pal
B K
BK
Department of Chemistry, Jadavpur University, Calcutta-700032, India.
Chowdhury
R P
RP
Mitra
B K
BK