needle near the union of tubes D and F as shown in Figure 1. The effect on column efficiency (compared with column efficiency when using sample valve alone) of different sizes of tubing used for D and F is shown in Table I. The greatest difference in the efficiency of the system is found a t low K', small i.d. column, and small sample volume. However, this difference with the most efficient design) would result in a loss of less than 3%in resolution since resolution is proportional to N1f2.At higher K' or with larger i.d. columns, the loss of efficiency is even less (
