GFAA

Figure 4. Schematic diagram of spectrophotometry
GFAA, which is designed for qualitative analysis and quantitative measurement of the indium composition, includes two parts, the dissolution of indium and spectrophotometry. Dissolution uses Fe³⁺to react with In³⁺ in the In(NO₃)₃ solution and form the complex anion [InBr4]^-, which generates an ion-associated complex with MIBK. Spectrophotometry measures the absorbance of light at specific wavelengths (325.6, 303.9). Figure 5. Indicates the schematic diagram of spectrophotometry. The characteristic spectral lines emitted by the indium hollow cathode lamp are selectively absorbed, which is proportional to the mass concentration of indium in a certain range.[5]

Figure 5. Flow chart of GFFA
The whole procedure is divided into three steps as shown in Figure 6. Digestion obtains the measurable In elements. In the Graphite furnace, indium ground state atomic vapour was formed after drying, ashing and atomisation. Ultimately, absorbance is analysed to obtain the concentration of indium in the calibration steps.[6]

GFFA has the advantages of strong selectivity and high sensitivity. With the addition of a matrix modifier (palladium nitrate-magnesium nitrate mixed solution), the relative standard deviation of the test method can reach less than 10%. As seen in Table 3, the more than 93% recovery rate presents a high measurement accuracy.

Table 4. Measuring range, precision, and accuracy of GFFA ^[7]

Figure.6 The relationship between the concentration and the absorbance

C: concentration of sample

x: concentration of sample on the calibration curve

y: concentration of standard solution on the calibration curve

s: concentration of standard solution

Indium

Indium

Characterization

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