Answer / kangchuentat

Answer 94 - Reference formula Rs = (difference in retention time) / (average width at the base) is used. (a) First equation : Rs = (Tb - Ta) / [ (Wa + Wb) / 2 ] = 2 (Tb - Ta) / (Wa + Wb). Second equation : Rs = (Tc - Ta) / [ (Wa + Wc) / 2 ] = 2 (Tc - Ta) / (Wa + Wc). (b) Substitute Ta = Tc - Tb, Wa = 20 s, Wb = 40 s and Wc = 30 s into first equation and second equation. First equation : Rs = 2 = 2 [ Tb - (Tc - Tb) ] / (20 + 40) = (2 Tb - Tc) / 30, 2 Tb - Tc = 60. Second equation : Rs = 4 = 2 [ Tc - (Tc - Tb) ] / (20 + 30) = Tb / 25, Tb = 100 s. Substitute Tb = 100 s into first equation gives 2 Tb - Tc = 2 x 100 - Tc = 200 - Tc = 60, then Tc = 200 - 60 = 140 s. Then Ta = Tc - Tb = 140 - 100 = 40 s. The answer is given by Kang Chuen Tat; PO Box 6263, Dandenong, Victoria VIC 3175, Australia; SMS +61405421706; chuentat@hotmail.com; http://kangchuentat.wordpress.com.

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