Purchase

Pass only Final Entry of purchase.Do not pass any entry of Samples so that complexities be avoided.

However, in your case,

Dr Purchases           Cr Free Samples

then

 Dr Free Samples    Cr Supplier A/c

In your case you have paid for the samples So u can show it as purchases.

Purchase dr

supplier   cr

if the bill is not avail then u can show it as retail purchases

Thanks Vardan