Application of two charge transfer complex formation reactions for selective determination of metformin hydrochloride in pharmaceuticals and urine

Future Journal of Pharmaceutical Sciences

Table 4 Results in evaluation of robustness and ruggedness of PCA and DDQ methods (expressed in %RSD)

Method	MEB taken, μg mL^-1	Robustness		Ruggedness
		Conditions altered		Ruggedness
		Volume of reagent (mL)^a	Reaction time altered^b	Inter-analysts’ (n = 3)	Inter-instruments’ (n = 3)
PCA method	160.0	0.96	0.72	0.76	1.82
	200.0	0.87	1.14	0.66	1.89
	240.0	2.98	0.81	0.88	1.07
DDQ method	32.0	0.64	0.69	0.62	0.78
	40.0	0.89	0.91	0.47	1.53
	48.0	1.68	0.54	1.44	1.51

^aThe volumes of PCA or DDQ added were 1 ± 0.2 mL. ^bReaction times were 10 and 10 ± 1 min (with PCA) and 2.0 and 2 ± 0.5 min (with DDQ)