Determination and Characterization of Molybdenum in Natural Water by Solvent Extraction-Atomic Absorption Spectrometry Using Graphite Furnace

摘要

A rapid, sensitive and selective method is described for the determination of molybdenum in natural waters and environmental materials by polarized Zeeman atomic absorption spectrometry with a pyrolytic graphite-coated graphite furnace. For the separation and concentration of trace amounts of molybdenum(VI ), the extraction behavior of molybdenum(VI)-8-quinolinolate complex with diisobutyl ketone(DIBK) was investigated. The high extractability of molybdenum with DIBK allows molybdenum to be concentrated about 200fold or more with a single extraction at pH 3.5. The molybdenum absorbance was measured at the wavelength of 313.3nm by using 20mm3 of organic phase. The optimum conditions obtained at heating stages were as follows: drying for 30s programmed from 1.50 to 200°C, charring at 500°C for 30s, atomizing at 2800°C for 15s and cleaning at 2900°C for 10s. The detection limit, defined as twice the standard deviation of the blank value, was found to be 0.05ng of molybdenum and the relative standard deviation was 1.5% for 2ng of molybdenum. Interferences of many metal ions can be effectively reduced by masking with EDTA and sodium fluoride.