Pickering Laboratories specializes in the manufacturing of cation-exchange columns and eluants for amino acid analysis. No other tech¬nique has been shown to match the reproducibility and selectivity of ion-exchange analysis with post-column Ninhydrin detection. Nor is there a chromatography technique that provides as much information; the 570/440 nm signal ratio for each amino acid is a constant and so offers information about peak purity. Pinnacle PCX post-column derivatization system provides a unique opportunity to combine eluant gradient capabilities of modern HPLC instruments with column temperature gradients. As might be expected, this capability also reduces the analysis time.