Derived metallicity for the G+M binary (HIP 12048), compared with five optical high-resolution studies. The metallicity of the M dwarf is indicated by the solid red line and the metallicity of the primary is indicated by the dashed blue line. The derived uncertainty for the primary in this work is shown with the semi-transparent blue area, and the corresponding uncertainty for the M dwarf in semi-transparent red area. Values and error bars for the primary from five studies selected from the literature are shown with different symbols.