UHPLC-PDA Assay for Simultaneous Determination of Vitamin D₃ and Menaquinone-7 in Pharmaceutical Solid Dosage Formulation

Table 6

Robustness study of vitamin D₃ and MK-7 by UHPLC.

Chromatographic conditions	Vitamin D3				MK-7
	Assay (%)	(min)		TF	Assay (%)	(min)		TF	Rs
Flow rate: 0.7	101.36	1.14	23540	0.95	101.23	3.34	28265	0.93	27.62
Flow rate: 0.5	101.29	1.37	23351	0.99	99.78	3.75	28233	0.98	27.59
(±0.1 mL min^−1)
Mobile phase (55 : 45)	100.17	1.26	23040	0.93	99.71	3.65	28865	0.99	27.62
Mobile phase (45 : 55)	99.53	1.25	23259	0.98	100.28	3.64	28223	0.93	27.61
(±5.0 mL)
Column temp. (45°C)	99.39	1.22	23390	0.97	101.36	3.62	28444	0.96	27.62
Column temp. (35°C)	99.81	1.28	23287	0.96	100.51	3.61	28304	0.98	27.63
(±5°C)
Wavelength (267 nm)	100.52	1.27	23289	0.99	100.32	3.65	28109	0.94	27.62
Wavelength (263 nm)	101.43	1.25	23401	0.96	99.83	3.63	28119	0.95	27.63
(±2 nm)
pH: 6.1	99.87	1.27	23540	0.96	100.34	3.64	28165	0.94	27.62
pH: 5.9	100.18	1.25	23387	0.93	100.39	3.63	28338	0.95	27.65
(±0.1)

: retention time, : theoretical plates, TF: tailing factor, and Rs: resolution.