In this book Evaluation of Hassira crude oil in Garmian, Sulaimai, Iraq was carried out for the first time and compared with the word oil specification. The results showed that the Hassira field seems to be one of best oil Iraqi fields in comparison with other oil production fields. Also, evaluations and comparisons of different sample preparation methods for trace element analysis in crude oil and its products have been discussed such as extraction induced emulsion breaking, dry ashing and wet digestion. Finally, a comparison between ICP-OES and F-AAS have been studied and were used for determination of trace elements.