柱前衍生-高效液相色谱法测定钢及合金中钨和钼

PRECOLUMN DERIVATIZATION HPLC DETERMINATION OF MOLYBDENUM AND TUNGSTEN IN ALLOY STEELS

以tiron作为柱前衍生试剂,用含3mmol·L-1pH 3.8的HOAc-NaOAc,40mmol·L-1TBA-Br和2mmol·L-1tiron的甲醇-水溶液(53+47)作流动相,在C18柱上,于15min内实现了WO42-、MoO42-的分离测定。钨和钼的检出限分别为5.98和3.20ng·ml-1。方法快速,选择性好,用于钢及合金中高含量钨和钼的测定,结果与标准值相符。

The RP-HPLC determination of molybdenum and tungsten was applied to steel analysis. Tiron was used as precolumn derivative reagent. The steel sample was dissolved in an appropriate acid mixture and a sodium hydroxide precipitation was made to separate molybdate and tungstate from the matrix elements. An aliquat of the filtrate containing molybdate and tungstate was taken and acidified to pH 6~8 with phosphoric acid, and transferred to a 25ml volumetric flask. Molydate and tungstate were reacted with tiron in an acetate buffer of pH 3. 8 to form stable complexes the absorbances of which were measured at 320nm. A methanol-water (53+47) solution, containing also 40mmol · L-1 TBA-Br, 2mmol · L-1 tiron and 3mmol·L-1 HOAc-NaOAc (pH 3. 8) was used as the mobile phase. Molybdate and tungsten in the solution as tiron complexes were eluted and separated on a Kromasil C18 column (150mm×4. 6mm, 5μm) within 20min. The detection limits for tungsten and molybdenum were found to be 5. 98ng ·ml-1 and 3. 20ng ·ml-1 respectively. The proposed method has been applied to the determination of W and Mo in some low and high alloy steel samples. The results obtained were in good comformity with the standard values.