试验表明:在乙醇-硫酸铵双水相体系中,所形成的乙醇相对钼与水杨基荧光酮红色络合物具有增敏作用.在pH 3的乙酸-乙酸钠缓冲溶液条件下,钼与水杨基荧光酮形成1∶2的稳定红色络合物,在乙醇-硫酸铵双水相体系的乙醇相中,该络合物的最大吸收波长为516 nm,与单一水溶液中络合物相比,发生了2 nm波长的红移现象.在乙醇相中钼(Ⅵ)-SAF络合物的表观摩尔吸光率为1.12×105L·mol-1·cm-1,钼(Ⅵ)质量浓度在20 mg·L-1以内与其对应的吸光度呈线性关系.方法的检出限(3S/N)为0.06 mg·L-1.该方法应用于粮食作物中微量钼的测定,测得方法的回收率为97.4%~100.1%.

It was found that the sensitivity of the red colored complex of Mo(Ⅵ)-salicylfluorone (SAF) with its mole ratio of 1 to 2,formed in pH 3.0 acetate buffer medium containing ethanol and ammonium sulfate (called bi-aqueous medium) was enhanced as compared with the same chromogenic reaction carried out in unitary aqueous medium without the addition of ethanol.Upon extraction by shaking the reaction mixture for 2 min,the Mo(Ⅵ)-SAF complex was transferred into the upper ethanol phase,having its absorption maximum at 516 nm (spectral change of bathochromic shift of 2 nm as compared with the Mo(Ⅵ)-SAF complex in unitary aqueous medium).Value of apparent molar absorptivity found was 1.12×105L·mol-1·cm-1 in ethanol phase.Linear relationship between values of absorbance and mass concentration of Mo(Ⅵ) was kept in the range within 20 mg·L-1,with detection limit (3S/N) of the method of 0.06 mg·L-1.The proposed method was applied to the determination of Mo(Ⅵ) in grain samples,giving values of recovery in the range of 97.4%-100.1%.