Mix NO Deg (PAP) % Concentration (μg/band) Recovery %
    DPH PAR PAP DPH PAR PAP
1 20 5 1.6 0.4 98.20 98.12 100.25
2 30 5 1.4 0.6 102.00 99.00 98.33
3 40 5 1.2 0.8 100.00 100.00 100.62
4 50 5 1 1 99.20 101.20 101.00
5 60 5 0.8 1.2 99.40 98.00 100.83
6 70 5 0.6 1.4 101.60 102.00 99.28
7 80 5 0.4 1.6 98.00 99.00 99.37
8* 0.00 5* 100* ZERO 99.20 ------- Zero
9* 0.00 0.05* 1* ZERO ------- 101.30 Zero
Mean ± SD 99.30± 1.45 99.50± 1.53 100.25± 0.98
*The ratio present in Panadol night® tablets
N.B: DPH concentration was determined in mixture No 8, while in mix No 9 PAR concentration was determined after dilution of mix No 8
Table 4: Determination of Paracetamol and Diphenhydramine Hydrochloride in presence of Para-aminopheno in laboratory prepared mixtures by the proposed densitometric method.