Some amino acids, organic acids, tetracyclines and organophosphates are metal chelators. Chelation during analysis of these compounds can distort the peak shapes and worsen the quantification accuracy. Residual metals on the packing surface were assumed to cause these problems. However, in the case of microanalysis, it has turned out that metals on the wetted parts such as tubing or frits also has a strong influence. Phosphate buffers are widely used in metal chelator analysis to improve the peak shapes, however, phosphate buffers cannot be used in LC/MS(/MS) because non‐volatile salts precipitate from these buffers.
Metal‐free columns have wetted parts made of PEEK instead of metal. In this technical note, some applications using metal‐free columns are shown and the advantages of metal‐free columns are described.