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Table 1 Optimization of the chromatographic conditions for determination of VPS by Method 1

From: Two novel UPLC methods utilizing two different analytical columns and different detection approaches for the simultaneous analysis of velpatasvir and sofosbuvir: application to their co-formulated tablet

Parameter No. of theoretical plates (N) Capacity factor (k′) Tailing factor (Tf)
Column (A) Column (B) Column (A) Column (B) Column (A) Column (B)
Column temperature °C
 Room temperature 2900.3 406.2 1.839 2.675 0.532 0.831
 30 °C 2941.6 1.987 0.660
 40 °C 4547.4 1009.7 2.183 2.038 0.536 0.900
 50 °C 5030.4 644.4 2.348 3.179 0.517 0.877
 60 °C 799.3 3.454 0.908
pH of mobile phase
 2.5 2900.3 406.2 1.839 2.675 0.532 0.831
 3.3 3921.4 408.2 2.744 4.150 0.528 0.947
 4.0 3305.7 410.6 3.976 6.425 0.491 0.924
Type of organic modifier of Conc 40% (v/v)
 Acetonitrile 2720.4 378.8 1.831 2.583 0.556 0.867
 Methanol 1140.1 365.4 1.843 2.621 0.514 0.907
 Ethanol 2304.3 352.9 1.870 2.592 0.413 0.871
Ratio organic modifier: mobile phase (acetonitrile) (v/v)
 40:60 3145.5 372.7 1.824 2.554 0.525 0.825
 60:40 2720.4 378.8 1.831 2.583 0.556 0.867
 80:20 2386.9 314.5 1.844 2.642 0.552 0.906
 90:10 2210.2 316.7 1.848 2.654 0.575 0.866
Effect of flow rate (mL/min)
 0.3 452.8 4.613 0.768
 0.5   205.0   1.433   0.750
 1.0 3551.6   2.376   0.571  
 1.2 2900.3 1.839 0.532
  1. \( {\text{Number of theoretical plates }}\left( {\text{N}} \right)\, = \,5.54\left( {\frac{{{t}_{{R}} }}{{{Wh}/2}} } \right)^{2} \)
  2. \( {\text{Tailing factor }}\left( {\text{T}} \right)\, = \,\frac{{{W}_{0.5} }}{{2{f}}} {\text{k}^{\prime}} \, = \,{{({\text{tR}} {-}{\text{ t}}0)} \mathord{\left/ {\vphantom {{({\text{tR}} {-}{\text{ t}}0)} {{\text{t}}0}}} \right. \kern-0pt} {{\text{t}}0}} \),