Left panel: observed spectrum (black points) around the Mg i triplet for the BWc-1 red clump star obtained with GIRAFFE (lower spectrum) and UVES (upper spectrum). The red lines represent the synthetic spectra computed with [Mg/H] = +0.34 and [Mg/H] = +0.38 respectively for GIRAFFE and UVES convolution. Right panel: comparison of observed (black points) and synthetic spectra (red lines) computed with [Mg/H] =  −0.16 for the red clump star BWc-93 and [Mg/H] = +0.42,+0.32,+0.22 for μLeo. The blue dotted lines and the green thick dashed lines represent the absorption of the Ca i line and of the CN lines respectively.