Li Z, Pan J, Jan T
Department of Chemical Engineering, Wuxi University of Light Industry, China.
Analyst. 2001 Jul;126(7):1154-9. doi: 10.1039/b101698i.
A novel spectrophotometric method based on a new reagent, 3,5-dibromo-4-hydroxyphenylflurone, was developed for the determination of molybdenum in plants and seeds. 3,5-Dibromo-4-hydroxyphenylflurone showed outstanding analytical characteristics for spectrophotometric determination of molybdenum. The reaction conditions are simple and stable. In 0.2 mol l(-1) phosphoric acid medium (which can combine with iron and other metal ions and greatly improves the selectivity of the color system), molybdenum(VI) reacts with 3,5-dibromo-4-hydroxyphenylflurone to form a 1:2 red complex with an absorption maximum at 530 nm, the color reaction can completed in 2 min and the absorbance of the molybdenum complex remains stable for at least 72 h at room temperature. Its stability constant is 1.21 x 10(28) at 25 degrees C. Beer's law is obeyed over the range 0-0.6 microg ml(-1) Mo(VI). The reagent has very high sensitivity and selectivity; the molar absorptivity of the complex is 1.35 x 10(5) 1 mol(-1) cm(-1) and the limit of quantification, the limit of detection and relative standard deviation (n = 10) were found to be 6.7 ng ml(-1), 2.2 ng ml(-1) and 1.01%, respectively. Cu (50000-fold), Fe (20000-fold), K (20000-fold), NH4+ (20000-fold), Mg (15000-fold), Zn (10000-fold), Na (10000-fold), Al (4000-fold), Ca (25000-fold), Mn (2000-fold), Ce (500-fold), Cr (400-fold) and Bi (200-fold) do not interfere with the determination of trace levels of molybdenum up to the excesses indicated. The selectivity is much superior to that of other published methods. The proposed method was applied to the direct determination of molybdenum in plants and seeds with satisfactory results. The synthesis of the reagent and conditions of color reaction were studied in detail.
基于新型试剂3,5 - 二溴 - 4 - 羟基苯基荧光酮开发了一种用于测定植物和种子中钼的新型分光光度法。3,5 - 二溴 - 4 - 羟基苯基荧光酮在分光光度法测定钼方面表现出优异的分析特性。反应条件简单且稳定。在0.2 mol l(-1) 磷酸介质中（该介质可与铁和其他金属离子结合，大大提高了显色体系的选择性），钼(VI) 与3,5 - 二溴 - 4 - 羟基苯基荧光酮反应形成1:2的红色络合物，其最大吸收波长为530 nm，显色反应可在2分钟内完成，钼络合物的吸光度在室温下至少72小时保持稳定。在25℃时其稳定常数为1.21×10(28)。在0 - 0.6 μg ml(-1) Mo(VI)范围内符合比尔定律。该试剂具有非常高的灵敏度和选择性；络合物的摩尔吸光系数为1.35×10(5) 1 mol(-1) cm(-1)，定量限、检测限和相对标准偏差（n = 10）分别为6.7 ng ml(-1)、2.2 ng ml(-1)和1.01%。铜（50000倍）、铁（20000倍）、钾（20000倍）、铵根离子（20000倍）、镁（15000倍）、锌（10000倍）、钠（10000倍）、铝（4000倍）、钙（25000倍）、锰（2000倍）、铈（500倍）、铬（400倍）和铋（200倍）在所示过量范围内不干扰痕量钼的测定。其选择性远优于其他已发表的方法。所提出的方法应用于直接测定植物和种子中的钼，结果令人满意。详细研究了试剂的合成及显色反应条件。
