Determination of Trace Molybdenum in Plants by Spectrophotometry with 4-hydroxy-3-nitrophenyl Azo Phenylfluorone

New reagent 4-hydroxy-3-nitrophenyl azo benzene fluorone was synthesize; In the presence of surfactant TritonX- 100 and HAc-NH3 buffer solution, reaction conditions and photometric properties of fluorone reagents with molybdenum were stud- ied. The results showed that the molar ratio of molybdenum and fluorone reagents formed the red complex, the maximum absorption wavelength of complex was 540 nm and the apparent molar absorptivity was 7.3×104 the buffer solution (pH= 4.68 of HAc-NH3) . Beer's law was obeyed when the content of molybdenum was in the range of 0-20μg / 25ml. The developed method has been applied to the determination of trace molybdenum in plants with satisfactory results.