Interlaboratory comparison of amino acid enantiomeric ratios in Pleistocene fossils

► Enantiomeric ratios (d/l values) are compared for different analytical methods. ► Mollusk and eggshell samples prepared by single labs were used for this comparison. ► Results from 5 reverse phase labs, 2 ion exchange labs, and 1 gas chromatography lab are reported. ► Sample preparation effects are minimized because homogenous liquids were used. ► Differences between methods are usually less than 10%, with some significant exceptions.