Spectrophotometric Determination of Trace-amounts of Gallium with 4-(6-Methoxy-8-quinolylazo)-phloroglucinol as Color Reagent in Microemulsoid

A new spectrophotometric method for determination of trace amounts of gallium(Ⅲ) was proposed,base on its reaction with 4-(6-methoxy-8-quinolylazo)-phloroglucinol (MOQAPG) in a microemulsoid composed of CPB,OP,n-butanol,n-heptane and water.It was found that in the microemulsoid with its mass ratio of m(CPB/OP)∶m(n-butanol)∶m(n-heptane)∶m(H2O)=0.25∶3.3∶0.8∶89.9,and buffered at pH 9.80 with borate buffer solution,a red colored complex was formed by the reaction of Ga(Ⅲ) with MOQAPG in the mole ratio of 1 to 2,having its absorption maximum at the wavelength of 525 nm and its apparent molar absorptivity (ε525) of 1.6×105L·mol-1·cm-1.Beer′s law was kept in the range of 7-800 μg of Ga(Ⅲ) per 1 L of solution.Detection limit (3S/N) of the method was found to be 1 μg·L-1.The proposed method was applied to determine contents of gallium in samples of coal and ore,giving results in consistency with the results obtained by AAS,and values of RSD′s (n=6) less than 5%.Test for recovery was made by standard addition method,and value of average recovery found was 102.7%.