Table 4.

Application of the standard addition technique for the determination of DEX in dosage forms using the proposed methods

Method	Taken (μg mL-1)	Tussilar tablets (10 mg/tab.)			Tussilar drops (1.0 g/15 mL)
		Added (μg mL-1)	Recoverya %	Reference method	Added (μg mL-1)	Recoverya %	Reference method
A	4	--	99.80		--	97.85
		2.0	100.50		2.0	99.50
		4.0	100.35		4.0	101.00
		6.0	100.20		6.0	100.25
		8.0	99.65		8.0	100.60
		10	100.80		10	99.25
	Meana ± SD (p=0.05)		100.22 ± 0.432	99.92 ± 0.85		100.08 ± 0.67	100.18 ± 0.81
	tb		0.026
	Fb		1.106
B	2	--	99.51		--	98.95
		2.0	99.96		2.0	99.50
		4.0	100.01		4.0	100.40
		6.0	99.10		6.0	100.55
		8.0	99.85		8.0	99.50
		10	100.30		10	99.90
	Meana ± SD (p=0.05)		99.97 ± 0.423	99.92 ± 0.85		99.80 ± 0.61	100.18 ± 0.81
	tb		0.296			0.798
	Fb		1.27			1.07
C	2	--	99.60		--	99.35
		2.0	100.45		2.0	99.70
		4.0	100.15		4.0	100.40
		6.0	100.30		6.0	99.20
		8.0	99.85		8.0	100.50
		10	99.60		10	99.75
	Meana ± SD (p=0.05)		99.99 ± 0.36	99.92 ± 0.85		99.82 ± 0.53	100.18 ± 0.81
	tb		0.09			0.826
	Fb		1.43			1.413
D	1.0	--	99.63		--	100.04
		1.0	99.91		1.0	99.50
		2.0	100.16		2.0	100.40
		4.0	99.10		4.0	100.55
		6.0	99.85		6.0	99.95
		8.0	100.20		8.0	99.90
	Meana ± SD (p=0.05)		99.81 ± 0.41	99.92 ± 0.85		100.06 ± 0.38	100.18 ± 0.81
	tb		0.302			0.436
	Fb		1.067			1.10

^aAverage of six determinations;

^bCalculated t- and F-value; tabulated t and F-value for five degrees of freedom; p=0.05 are 2.57 and 5.05.