Department of Chemistry, University of Tennessee, 552 Buehler Hall, Knoxville, TN 37996-1600, USA.
J Chromatogr A. 2010 Dec 3;1217(49):7677-89. doi: 10.1016/j.chroma.2010.10.016. Epub 2010 Oct 14.
The efficiencies of two narrow bore columns (100 mm and 50 mm × 2.1 mm) packed with 1.7 μm totally porous BEH-C(18) particles were measured on two very high pressure liquid chromatographs (Acquity from Waters and 1290 Infinity HPLC System from Agilent) operating at maximum pressures of 1034 and 1200 bar, respectively. The probe compounds were a mixture of uracil, acetophenone, toluene, and naphthalene eluted in a 50/50 (v/v) solution of acetonitrile and water at 303 K with a flow rate of 0.40 mL/min. The apparent efficiencies of columns, which lumps the consequences of band broadening due to the column and the system contributions, may depend much on the extra-column volumes of the instruments used. Actually, it is known for a long time that the apparent column performance is strongly affected by the instrument characteristics, including the diameter of the connecting tubes, the injection technique (with or without needle seat capillary), and the detection cell volume. When the 1290 Infinity HPLC System is equipped with a needle seat, an inlet and an outlet connecting capillary tube with inner diameters around 115 μm, its extra-column variance for a 0.1 μL injection volume is 9.2 μL(2) while that of the Acquity instrument is 6.9 μL(2). Minor modifications suggested by their respective manufacturers allowed significant reductions of these variances, to 6.2 and 3.9 μL(2), respectively. Yet, in their optimized configurations and for weakly retained compounds (k≃1), these modern, sophisticated instruments cannot provide more than 75% (1290 Infinity) and 85% (Acquity) of the maximum efficiency of a 2.1 mm × 50 mm BEH column. For more strongly retained compounds (k>4), in contrast, they are both able to provide more than 95% of the maximum expected efficiency.
在两台最大压力分别为 1034 bar 和 1200 bar 的超高效液相色谱仪（Waters 的 Acquity 和 Agilent 的 1290 Infinity HPLC 系统）上，分别测量了两根填充 1.7 μm 全多孔 BEH-C(18)颗粒的小口径柱（100mm 和 50mm×2.1mm）的效率。探针化合物为在 303 K 下以 0.40 mL/min 的流速洗脱的嘧啶、乙酰苯、甲苯和萘的混合物，以 50/50（v/v）乙腈和水的溶液洗脱。柱的表观效率（将柱和系统贡献引起的带宽展宽的结果合并在一起）可能在很大程度上取决于所用仪器的柱外体积。实际上，长期以来人们都知道，仪器的特性（包括连接管的直径、进样技术（带或不带针头座毛细管用）和检测池体积）对表观柱性能有很强的影响。当 1290 Infinity HPLC 系统配备针头座时，内径约为 115μm 的进样和出样连接毛细管用其 0.1μL 进样体积的柱外方差为 9.2μL(2)，而 Acquity 仪器的柱外方差为 6.9μL(2)。它们各自制造商提出的一些较小的改进可以显著降低这些方差，分别降低到 6.2μL(2)和 3.9μL(2)。然而，在其优化配置和对弱保留化合物（k≃1）的情况下，这些现代、复杂的仪器不能提供超过 2.1mm×50mm BEH 柱最大效率的 75%（1290 Infinity）和 85%（Acquity）。相反，对于更强保留的化合物（k>4），它们都能够提供超过最大预期效率的 95%。
