New Stability Indicating Method for Quantification of Impurities in Amlodipine and Valsartan Tablets by Validated HPLC
Table 2
Results of analysis of forced degradation study samples using the proposed method, indicating percentage of degradation and peak purity of amlodipine and valsartan.
(a)
Degradation in
Degradation sample
Amlodipine imp-A (%)
Valsartan imp-B (%)
Maximum individual unknown impurity (%)
Total impurities (%)
As such sample
Placebo + amlodipine and valsartan
0.12
0.07
BRL
0.24
1 N HCl (5 mL)
Placebo + amlodipine and valsartan
0.11
0.07
0.06
0.34
1 N NaOH (5 mL)
Placebo + amlodipine and valsartan
0.11
0.07
0.06
0.34
30% H2O2 (5 mL)
Placebo + amlodipine and valsartan
5.16
ND
0.31
6.35
UV light
Placebo + amlodipine and valsartan
0.10
0.07
0.06
0.28
Thermal condition at 80°C
Placebo + amlodipine and valsartan
0.11
0.07
0.06
0.34
ND: not detected; BRL: below reporting level (BRL = 0.05%).
(b)
Degradation samples
Peak area
Peak area
Retention time (min)
Purity angle
Purity threshold
Match angle
Match threshold
Placebo + drug degradation in 5 mL of 1 N HCl
Amlodipine
2598903
12.30
0.236
0.432
0.138
1.159
Valsartan
2943627
40.92
0.050
0.291
0.038
1.025
Placebo + drug degradation in 5 mL of 1 N NaOH
Amlodipine
2599981
12.36
0.233
0.448
0.128
1.164
Valsartan
2938404
40.91
0.047
0.287
0.042
1.025
Placebo + drug degradation in 5 mL of 30% H2O2
Amlodipine
2483045
12.38
0.223
0.431
0.138
1.168
Valsartan
2891144
40.92
0.063
0.319
0.055
1.038
Placebo + drug degradation in UV light
Amlodipine
2586948
12.05
0.234
0.438
0.220
1.162
Valsartan
2933545
40.76
0.059
0.303
0.109
1.031
Placebo + drug degradation in thermal conditionat 80°C
