Comprehensive Assessment of Degradation Behavior of Simvastatin by UHPLC/MS Method, Employing Experimental Design Methodology

Table 4

Obtained results from validation of the proposed method.

	Imp.E	Imp.G	SIM	MSIM	Imp.B	Imp.C	Imp.D
System suitability
Resolution	/	4.44	4.27	6.83	11.20	1.56	38.26
NTP	79895	110461	169356	268485	253612	184417	292527
T	1.01	1.02	1.04	1.05	1.07	1.02	1.02
Linearity ^(1)
Regression coefficient	0.9969	0.9994	0.9920	0.9980	0.9990	0.9970	0.9997
Slope	33806	15647	31722	10155	27192	21212	10765
Intercept	6077	388	6375	368	253	2171	401
Response factor	1.50	0.55	1.0	0.36	0.96	0.75	0.38
Precision ^(2)
Method precision	7.26	NA	NA	9.04	6.12	NA	NA
Intermediate precision (F –test)	1.86	1.02	NA	1.85	1.05	1.02	1.03
Accuracy given as recovery (%) ^(3)
50	98.8 ± 0.5	100.4 ± 0.6	100.5 ± 0.5	98.8 ± 0.6	99.5 ± 1.5	101.0 ± 0.2	100. 7 ± 1.0
100	98.3 ± 0.3	99.1 ± 1.4	100.2 ± 0.1	99.1 ± 0.7	99.7 ± 0.8	98.3 ± 0.9	100.3 ± 0.9
150	98.8 ± 0.2	99.1 ± 0.1	99.9 ± 0.6	99.1 ± 0.1	99.2 ± 0.2	101. 5 ± 0.2	99.6 ± 1.0
Sensitivity ^(4)
LOD (μg/mL)	0.12	0.06	0.03	0.12	0.12	0.12	0.12
RSD	11.37	30.18	6.92	9.12	13.60	10.77	2.58
LOQ (μg/mL)	0.4	0.4	0.1	0.4	0.4	0.4	0.4
RSD	3.98	1.30	9.29	4.79	1.58	3.30	6.64

(1) Nine solutions of SIM in the concentration ranging from 0.1 μg/mL to 1.5 μg/mL and nine solutions of all impurities in the concentration ranging from 0.4 μg/mL to 6 μg/mL were analyzed.
(2) The repeatability was shown by 6 replicate injections of the standard solution in concentration of 1 μg/mL and the intermediate precision was performed on 6 samples in the two following days using the same equipment.
(3) Determined in triplicate at three concentration levels of 50%, 100%, and 150% by spiking the prequantified samples with a known amount standard of impurities.
(4) The LOD and LOQ were estimated at a signal-to-noise ratio of 3:1 and 10:1, respectively, for each impurity by injecting a series of dilute solutions with known concentration.
NA: not applicable, MSIM: methyl simvastatin, and RSD: relative standard deviation.