The hazards effect of persistent organic pollutants, POPs, on the human health has lead us to modify the ASTM method D-5175 to enhance both sensitivity and selectivity of their simultaneous separation. As their separation is difficult- due to the similarity in their chemical and physical properties- that lead to co-elution in extraction, we proposed a validated method for their simultaneous determination using liquid/liquid microextraction followed by GC/MS in the SIM mode. The method is advantageous since the time needed for the chromatographic analysis of all analytes is less than 17 min. Method Detection Limits (MDLs) and Limit of Detection (LODs) reached sub- ppb levels and in many cases are lower than those achieved in the standard test method ASTM D-5175 for many analytes. Besides, three pesticides namely: Hexachlorocyclopentadiene, p,p’-DDE and trifluralin have been added to the method with good accuracy and precision. Application to several environmental samples has been successfully assessed and supported by proficiency testing samples provided from Absolute Standards®, Inc.