Biological Safety Studies and Simultaneous Determination of Linagliptin and Synthetic Impurities by LC-PDA

Table 1

Parameters of system suitability of the analytical method developed and results recommended by the FDA [25].

Parameter	Recommended FDA [22]	IMP 1	LGT	IMP 2	IMP 3
Retention time (min)	—	3.91	5.52	7.47	8.42
Retention factor (k)	k′ > 2	2.03	3.27	4.79	5.52
Tailing factor (T)	T ≤ 2	1.06	1.20	1.14	1.19
Efficiency (N)	N > 2000	5666	8466	13391	13234
Resolution (R)	R > 2	—	3.63	3.68	2.63

LGT: linagliptin; IMP 1: impurity 1; IMP 2: impurity 2; IMP 3: impurity 3.