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An industrial molten metal chemical analyzer based on laser-induced breakdown spectroscopy (LIBS) has been used to perform concentration analysis of important trace elements (Fe,Si,Cr,Mn,Ti, 20-3000 ppm) in liquid aluminum. In order to rule out accidental correlations between different elements in the spectral analysis, the impurity concentration of the measured samples was fully randomized. Reference concentration measurements were performed using arc-spark optical emission spectroscopy (spark-OES) on solid samples cast from the full volume of the LIBS-analyzed melt. For elements Fe, Cr, Mn and Ti, correlation coefficients and prediction uncertainty of LIBS measurements, using a linear correlation model, are shown to be determined mainly by random measurement error, which was of the order of 1% for both the LIBS analysis and the spark-OES analysis for concentrations above 100 ppm for all of the investigated elements. In the case of silicon, we postulate that inhomogeneous solidification is leading to a reduced absolute accuracy of spark-OES reference measurements and a corresponding increase in the minimum prediction uncertainty. The results confirm that LIBS analysis of molten aluminum can be used for on-line process control in the aluminum industry by providing measurement accuracy comparable of current industry-standard laboratory analysis methods.