Study on the color reaction of chromogenic reagent 9-(2-hydroxyl-5-p-methyl-azophenyl) phenylfluorone with molybdenum and its application

A new chromogenic reagent 9-(2-hydroxyl-5-p-methylazophenyl) phenylfluorone(HMAPPF) has been synthesized and developed for spectrophotometric determination of trace molybdenum in alloy steel samples in the work,and the molecule structure of HMAPPF was also confirmed by using IR,NMR and MS analysis.In the mixed acid of HCl and H3PO4,MoⅥ reacts with the reagent to form a red complex with a maximum absorption peak at 522 nm in the presence of CTMAB,which apparent molar absorptivity is found to be 1.54×105 L·mol-1·cm-1.The reaction can be completed rapidly under room temperature and the absorbance of the complex can be stable for 12 h at least.In 25 mL solution,Beer's law is obeyed in the range of 0-12 μg for molybdenum.Moreover,the color reation system has good selectivity,most of metal ions can be tolerated in considerable amounts,the property is beneficial to determine trace molybdenum in various complex samples.Proposed method has been applied to measure molybdenum in alloy steel with satisfactory results,the recovery and RSD obtained using standard addition method were 97.8%-102.5% and 0.25%-0.30%,respectively.