Engelhardt H, Lobert T
Institute for Instrumental and Environmental Analysis, University of the Saarland, Im Stadtwald, D-66123 Saarbruecken, Germany.
Anal Chem. 1999 May 1;71(9):1885-92. doi: 10.1021/ac981198x.
A new test procedure is proposed for the characterization of packed RP columns with respect to their metal content. It is based on the peak asymmetry of 2,2'-bipyridyl, which can be directly correlated to the metal content of the stationary phase. Since an unbuffered eluent (methanol/water, 49:51 w/w) is used, the influence of the simultaneously present silanol groups on peak asymmetry is assessed via 4,4'-bipyridyl, which exhibits no chelating activity. A metal factor, MF, is introduced, which is the ratio of the peak asymmetries of 2,2'-bipyridyl and 4,4'-bipyridyl multiplied by 100. The superiority of this test compared to others is demonstrated via various commercially available columns. It is also demonstrated that columns continuously collect metal ions from the column components and the instrument hardware. Stainless steel nets and frits are the principal source of the metallic contamination. But even in totally metal-free LC systems, the stationary phase collects metal ions from the HPLC grade eluent components.
提出了一种用于表征填充反相（RP）柱金属含量的新测试方法。该方法基于2,2'-联吡啶的峰不对称性，其可直接与固定相的金属含量相关联。由于使用的是未缓冲的洗脱液（甲醇/水，49:51 w/w），通过4,4'-联吡啶评估同时存在的硅醇基对峰不对称性的影响，4,4'-联吡啶不具有螯合活性。引入了一个金属因子MF，它是2,2'-联吡啶与4,4'-联吡啶峰不对称性的比值乘以100。通过各种市售柱证明了该测试相对于其他测试的优越性。还证明了柱子会持续从柱组件和仪器硬件中收集金属离子。不锈钢网和烧结片是金属污染的主要来源。但即使在完全无金属的液相色谱系统中，固定相也会从高效液相色谱级洗脱液成分中收集金属离子。
