Standard of n-alkanes (C 7 to C 40 ) was supplied
as 1036 l g ml ?1 hexane solution (Code No.: 49452-U) by Supelco
(Bellofonte, USA) and it was used as stock solution; solutions for
further studies were prepared by diluting the stock solution with
hexane. The above solutions were stored at 4 ?C, and protected
from light.