Determination of gallium and indium by solution cathode glow discharge as an excitation source for atomic emission spectrometry

In this paper, gallium (Ga) and indium (In) in water samples were determined by atomic emission spectrometry (AES) with solution cathode glow discharge (SCGD) as an excitation source. The optimal working conditions for the detection of Ga and In by proposed method are 660 V discharge voltage, 3.0 mL min(-1) solution flow rate and pH = 1.0 HNO3 as supporting electrolyte. Under these conditions, it is found that there are no obvious inter-ferences from most of the foreign ions when they exist in 20-fold excess over the In. But for Ga, the interferences from foreign ions are severe. The linear correlation coefficient (R-2) is better than 0.99 with a range of 1-40 mu g mL(-1) for Ga and 0.1-30 mu g mL(-1) for In. The limits of detection (LODs) for Ga and In are 0.10 and 0.016 mu g mL(-1), respectively. The relative standard deviations (RSDs) are 2.9% for Ga and 3.9% for In, and the power is below 55 W. To validate the utility and accuracy of the proposed system, two water samples spiked with various concentration (0.3-20 mu g mL(-1)) of Ga and In are directly determined, and the measured results are only in good agreement with spiked values of In. After diluted 10 times for water samples, the spiked values (0.3-20 mu g mL(-1)) of Ga agree well with the measured value, suggesting that the matrix can interfere with the determination of Ga. The satisfactory recoveries between 90% and 109% of In and Ga are achieved.