Ultratrace Gold in High-Purity Graphite by High-Resolution Continuous Light Source Graphite Furnace Atomic Absorption Spectrometry with Hanging Droplet Microextraction

XIAO Fang; ZHANG Tianyuan; ZHANG Liping; LIU Lu; MAO Xiangju; NI Wenshan

doi:10.15898/j.ykcs.202406210137

Rock and Mineral Analysis > 2024 > 43(5): 734-743. > DOI: 10.15898/j.ykcs.202406210137

XIAO Fang，ZHANG Tianyuan，ZHANG Liping，et al. Ultratrace Gold in High-Purity Graphite by High-Resolution Continuous Light Source Graphite Furnace Atomic Absorption Spectrometry with Hanging Droplet Microextraction[J]. Rock and Mineral Analysis，2024，43（5）：734−743. DOI: 10.15898/j.ykcs.202406210137

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Ultratrace Gold in High-Purity Graphite by High-Resolution Continuous Light Source Graphite Furnace Atomic Absorption Spectrometry with Hanging Droplet Microextraction

XIAO Fang^{1, 2, 3,},
ZHANG Tianyuan^{1, 2, 3},
ZHANG Liping^{1, 2, 3},
LIU Lu^{1, 2, 3},
MAO Xiangju^{1, 2, 3},
NI Wenshan^{1, 2, 3, ,}

1.
Zhengzhou Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Zhengzhou 450006, China
2.
China National Engineering Research Center for Utilization of Industrial Minerals, Zhengzhou 450006, China
3.
Key Laboratory for Polymetallic Ores’ Evaluation and Utilization, Ministry of Natural Resources, Zhengzhou 450006, China

More Information

Received Date: June 20, 2024
Revised Date: August 08, 2024
Accepted Date: August 12, 2024
Available Online: September 29, 2024

Abstract

ABSTRACT

The major challenge in accurately determining ultratrace gold in high-purity graphite is how to achieve effective separation and high enrichment of it (0.1−1ng/mL) in the sample solution, while minimizing the secondary pollution introduced by vessels, reagents, materials, environment, and equipment during the sample pretreatment process. A new method for the analysis of ultratrace gold in high-purity graphite is established by ashing and acid dissolution in a platinum dish, followed by microextraction with a hanging droplet of tributyl phosphate. Firstly, the fixed carbon in the sample was removed by high-temperature burning in a platinum vessel; then, the ash was completely dissolved into a sample solution using hydrofluoric acid-aqua regia-perchloric acid; next, micro-upgraded tributyl phosphate droplets were used as an extractant to separate and enrich gold from the sample solution; finally, gold in the droplets was determined using high-resolution continuum source graphite furnace atomic absorption spectrometry. The experimental results showed that by using 2.5μL of tributyl phosphate (chloroform volume fraction 20%) as the extractant, gold can be extracted from a sample solution in 10% hydrochloric acid medium for 2min, and the enrichment factor for gold can reach up to 283 times. Under the selected experimental conditions, the mass concentration of gold showed a good linear relationship with its absorbance values in the range of 0.1 to 2.0ng/mL. The correlation coefficient (r) was 0.999, and the detection limit of the method was 0.11ng/g. Interference tests showed that the presence of certain coexisting elements such as sodium, magnesium, and aluminum in the sample solution had no effect on the determination of gold. According to the experimental method, the gold content in five high-purity graphite samples was measured. The relative standard deviation (RSD, n=6) of the results was 1.5%−4.9%, and the recovery rate was 94.9%−105.3%.
- high purity graphite,
- hanging droplet microextraction,
- tributyl phosphate,
- graphite furnace atomic absorption spectrometry,
- ultratrace,
- gold

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References (27)

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