Object To find a method with highly accuracy and precision to evaluate Formaldehyde Residues in fuzhu by study and compare the results between two methods of sample pretreatments and two methods of determination.The experimental condition is selected by replicated orthogonal experiment. Method 1.The level of formaldehyde(HCHO),CV and recycle rate are compared in different sample pretreatment groups,determination method groups.Replicated orthogonal experiment(L_9(3~3))is used to find the major influence fact...