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

BMC Chemistry

Table 2 Optimization of the chromatographic conditions for the determination of SFV by Method 2

Parameter	No. of theoretical plates (N)		Capacity factor (k′)		Tailing factor (T_f)
Parameter	Column (A)	Column (B)	Column (A)	Column (B)	Column (A)	Column (B)
Column temperature °C
25 °C	4354.9	1014.2	1.147	4.638	0.475	0.629
40 °C	2950.3	756.4	1.057	4.404	0.506	0.772
50 °C	2620.8	677.9	0.989	4.208	0.471	0.73
65 °C	1895.1	468.9	0.871	3.792	0.468	0.679
pH of mobile phase
2.5	4354.9	1014.2	1.147	4.638	0.475	0.629
3.5	3981.2	1089	1.145	4.667	0.526	0.588
5	4617.2	1066.9	1.145	4.667	0.455	0.572
Type of organic modifier of Conc 40% (v/v)
Acetonitrile	4390.4	1004.5	1.236	4.667	0.446	0.679
Methanol	5073.4	1214.5	1.179	4.738	0.474	0.664
Ethanol	3342	925.4	1.175	4.708	0.481	0.65
Ratio organic modifier: mobile phase (Acetonitrile) (v/v)
40:60	4354.9	1100.3	1.147	4.696	0.475	0.677
60:40	1925.3	1004.5	1.173	4.667	0.453	0.679
80:20	7501.7	1648.5	1.187	4.75	0.468	0.647
90:10	8304.6	2064.8	1.19	4.792	0.458	0.653
Effect of flow rate (mL/min)
0.3		1041		8.196		0.816
0.5		1090.7		4.613		0.613
1	5093.6		1.53		0.287
1.2	1117.9		1.175		0.465

\( {\text{Number of theoretical plates }}\left( {\text{N}} \right)\, = \,5.54\left( {\frac{{{t}_{{R}} }}{{{Wh}/2}} } \right)^{2} \)
\( {\text{Tailing factor }}\left( {\text{T}} \right)\, = \,\frac{{{W}_{0.5} }}{{2{f}}}{\text{k}^{\prime}} \, = \,{{({\text{tR}} {-}{\text{ t}}0)} \mathord{\left/ {\vphantom {{({\text{tR}} {-}{\text{ t}}0)} {{\text{t}}0}}} \right. \kern-0pt} {{\text{t}}0}} \),