In this stady, LDH was synthesis by co-precipitation method. Then coupled with head space single drop microextraction for extract lactic acid, acetic acid, formic acid in a Human’s plasms and Human’s urine. These analytes were be to the esthers by added 40 µL of isopropyl alcohol and 30 µL of BF 3 at 50 ? C. Then analytes were detected by gas chromatography with FID detector. Different parameters affecting the extraction efficiency were investigated and optimized. The optimized conditions were as follows: 20 min extraction time at the temperature of 50 ? C , Sample pH=7. Linear dynamic ranges for lactic acid and acetic acid between 10-200 µg/lit, for formic acid between 310-1000 µg/lit. The detection limits for acetic acid and lactic acid 1µg/lit , formic acid 31µg/lit. The relative standard deviations were lower than 10% for all samples. Spiking recoveries were in the rang of 76-102%.
