Liquid-liquid extraction of molybdenum thiocyanate with hexamethyl phosphortriamide and direct spectrophotometric determination in the organic phase

A sensitive and selective method for estimation of trace molybdenum with fairly common reagents has been developed. The Mo-thiocyanate complex is extracted with hexamethyl phosphortriamide and chloroform from 0.75-1.5M hydrochloric acid. The molar absorptivity is 1.76 x 10(4) 1.mole(-1).cm(-1). The system obeys Beer's law at 460nm over the molybdenum concentration range 0.75-5ppm. The method is simple, rapid, and requires no additional reducing agent. It is generally free from interference by most of the metals commonly associated with molybdenum, including rhenium. Molybdenum in alloy steel has been successfully determined.