Development and Validation of a Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Guaifenesin and Dextromethorphan Impurities in Pharmaceutical Formulations
Table 8
Accuracy of the method.
Compound
% Recovery at each levela
LOQ
0.1%
0.2%
0.4%
0.8%
1.0%
GN-Impurity A
98.5
99.5
101.2
96.7
99.9
103.5
GN-Impurity B
105.6
102.7
99.7
105.1
98.5
97.5
GN-Impurity C
102.6
105.6
101.9
106.1
103.5
102.1
GN-Impurity D
95.6
97.2
96.5
95.8
96.5
98.5
DN-Impurity A
93.5
96.5
95.2
94.2
98.5
96.7
DN-Impurity B
98.5
96.7
99.9
98.9
97.5
96.5
DN-Impurity C
101.1
102.3
102.5
103.7
102.5
101.8
DN-N-oxide
105.6
106.5
105.1
104.5
102.9
103.7
DN-NFM Impurity
101.5
98.5
102.5
101.2
99.5
98.6
DN-NFO Impurity
107.1
105.6
106.9
105.8
106.5
105.8
GN
98.5
96.5
97.2
96.8
97.4
98.7
DN
99.2
98.5
97.1
99.5
100.5
101.2
Average of six determinations at LOQ level & 1.0% level and three determinations at remaining levels.
