Abstract: Different procedures for pretreatment of foodstuff samples were described and chosen according to different kinds of foodstuff.Conditions of sample pretreatment,including the choice of solvents for extraction of the 4 additive compounds to be determined (benzoic acid,sorbic acid salicylic acid,soluble saccharin),the choice of suitable acidity (pH value) of the sample solutions and the purification condition to remove the interfering substances,were studied thoroughly.After pretreatment of the sample,the clear sample solution was submitted to HPLC analysis.Separation was performed by using ODS C18 column and mobile phase composed of methanol and 0.02 mol·L-1 ammonium acetate solution mixed in the ratio of 9+91 by volume.Diode array detector at 230 nm was used in the measurements.Qualitative analysis was carried out according to the retention time and checking with characteristic spectra.External standard method was used in the determination by measuring the peak area in respect to the concentration of the compound determined.Detection limits for all the 4 compounds were found to be less than 0.000 1 g·L-1.Values of recovery of the compounds found by the standard addition method were in the range 82.3%-109.5%.Precision of the method was also tested,giving values of RSD′s (n=8) less than 10%.