Single granular activated carbon microextraction and graphite furnace atomic absorption spectrometry determination for trace amount of gold in aqueous and geological samples

A new and simple method was developed for preconcentration trace amount of gold in aqueous and mineral samples. The method was based on the sorption of gold on granular activated carbon (AC) in acidic medium (hydrochloric acid) and subsequently direct determination by graphite furnace atomic absorption spectrometry (GFAAS). A small particle of adsorbent was delivered to small volume of sample. After extraction, AC removed and analyzed directly by GFAAS. Several factors influencing the extraction efficiency, such as the hydrochloric acid concentration, sample volume and extraction time were studied as well as effect of potential interfering ions. The preconcentration factor 50 was obtained. The limit of detection (LOD) of gold in water and soil samples was 0.007 μg L− 1 and 0.9 ng g− 1, respectively. The proposed method was applied successfully to the determination of trace amount of gold in environmental and geological samples. In order to validate the developed method, two certified reference materials: Platinum Ore (SARM-7B) and Copper Ore Mill Heads (No. 330) were analyzed and the determined values obtained were in good agreement with the certified values and recovery was obtained in the range of 80-118%. The relative standard deviations (RSD) for the spiking levels of 0.5 μg L− 1 in the real samples was 4%, (n = 15).