\[k = \frac{t_R - t_M}{t_M} = K\,\frac{V_S}{V_M}\]
含义Meaning
溶质在固定相中停留时间与在流动相中时间之比，等于分配系数乘以相比。k 在 2–10 之间分离较好、时间适中。
Time spent in the stationary phase relative to the mobile phase — the partition coefficient times the phase ratio. k of about 2–10 balances resolution and run time.
符号说明Symbols
| 符号Symbol | 含义 Meaning | 单位 Unit |
|---|---|---|
| \(t_R\) | 保留时间retention time | min |
| \(t_M\) | 死时间（不保留物）dead time (unretained) | min |
| \(K\) | 分配系数 c_S/c_Mdistribution constant c_S/c_M | 1 |
| \(V_S/V_M\) | 相比phase ratio | 1 |
推导Derivation
溶质只有在流动相中才前进，所以 \(t_R = t_M(1 + n_S/n_M)\)。
Solutes move only while in the mobile phase, so \(t_R = t_M(1 + n_S/n_M)\).
\(n_S/n_M = KV_S/V_M = k\)，即得。
\(n_S/n_M = KV_S/V_M = k\).
适用条件与局限Assumptions & limitations
假设线性等温线（低浓度）；过载时峰形拖尾或前伸，k 随进样量变化。
Linear isotherm assumed; overload distorts peaks.