In the present process the end of 1st cut is determined by the vapour temeprature. As it reach 155dg C the collection of 1st cut is stopped and then the product cut is started. this 1st cut may be 5-10% of the feed quantity. the product cut is collected till the complete vapour is removed and no more evaporation taking place. the left over residue will be around5-10% of the batch. the intial 1st cut contains about 20-25% of the product in it.  