Extraction spectrophotometric determination of maneb with 1-(2'-pyridylazo)-2-naphthol (PAN).
A rapid, sensitive, simple and selective spectrophotometric method has been developed for the determination of micro-quantities of maneb (manganese ethylenebisdithiocarbamate) after extraction of the manganese-PAN complex in isobutyl methyl ketone (MIBK). The complex absorbs strongly at 550 nm. Beer's law is obeyed over the concentration range 0.37-3.75 microg/ml. The molar absorptivity was found to be 4.1 x 10(4) l. mole(-1) . cm(-1). The developed method has been applied to the determination of maneb in commercial formulations, synthetic mixtures, grain and in the presence of various other dithiocarbamates.
Spectrophotometric determination of maneb by ternary complex formation with PAR and CTAB.
A rapid, simple, direct, and sensitive method has been developed for the determination of maneb (manganese ethylenebisdithiocarbamate) based on the formation of manganese-4-(2'-pyridylazo) resorcinol complex by a ligand displacement reaction, which is rendered water soluble by a cationic surfactant cetyltrimethylammonium bromide (CTAB) by the formation of an ion association complex. Beer's law is obeyed over the concentration range 0.08-2.4 mug/ml of the final solution at 500 nm in pH range 8-12. The molar absorptivity and Sandell's sensitivity are calculated to be 8.84 x 10(4) l.mol(-1).cm(-1) and 0.003 mug/cm(2), respectively. The developed method has been applied to the determination of maneb in commercial formulations, synthetic mixture, grain samples and vegetables.
Determination of nickel in high-purity niobium, tantalum, molybdenum and tungsten metals by chloroform extraction of nickelII dimethylglyoximate
Abstract A spectrophotometric method for determining 0.0005–0.10% of nickel in high-purity niobium, tantalum, molybdenum and tungsten metals is described. After sample dissolution and pH adjustment to 6.0, nickelII dimethylglyoximate is extracted with chloroform from an ammonium tartrate-boric acid medium. The chloroform extract is washed with dilute ammonia solution to remove interfering impurities, and nickel is determined spectrophotometrically at 370 mμ directly in the extract.