Development and Validation of a Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Guaifenesin and Dextromethorphan Impurities in Pharmaceutical Formulations

Table 3

System suitability results.

Parameter	% RSD* of standard		Theoretical plates*		Tailing factor*		Resolution 1	Resolution 2
	GN	DN	GN	DN	GN	DN
As such method	0.5	0.7	45320	498659	1.0	1.0	2.7	2.3
At 0.6 mL/min flow rate	1.2	0.6	41091	495497	1.0	1.0	2.9	2.5
At 1.0 mL/min flow rate	0.9	0.4	45828	515551	1.0	1.0	2.5	2.2
At 50°C column temperature	1.5	0.8	45321	508966	1.0	1.0	2.6	2.3
At 60°C column temperature	2.1	2.3	40929	515807	1.0	1.0	2.9	2.6
At pH 2.8 (buffer pH)	1.1	0.5	43970	463987	1.0	1.0	2.4	2.3
At pH 3.2 (buffer pH)	0.7	1.5	44619	532891	1.0	1.0	2.6	2.7

∗Average of six replicate standard injections.