The　intermediates　of　photodegradation　and　microbial　degradation　of　pirimicarb　insecticide　were　investigated　by　liquid　chromatography　coupled　with　ion-trap　mass　spectrometry　(LC-IT-MS).　Different　intermediates　were　detected　in　the　photodegradation　and　microbial　degradation　of　pirimicarb.　In　the　photodegradation　of　pirimicarb　in　aqueous　solution　2-dimethylamino-5,6-dimethyl-4-hydroxypyrimidine　(MW　=　167),　2-methylamino-5,6-dimethylpyrimidin-4-yl-dimethylcarbamate　(MW　=　224)　and　2-formylamino-5,6-dimethylpyrimidin-4-yl-dimethylcarbamate　(MW　=　252)　were　the　main　products.　It　was　found　that　2-dimethylamino-5,6-dimethyl-4-hydroxypyrimidine　(MW　=　167)　was　the　major　product　in　the　microbial　degradation　of　pirimicarb　in　soil.　©　2009　Elsevier　B.V.　All　rights　reserved.