Abstract:To establish a method for simultaneous determination of methyl carbamate and ethyl carbamate in solid，semisolid and liquid substrates with internal standard by GC-MS/MS.Ethyl carbamate-D5was used as internal standard.Multiple reaction monitoring（MRM）mode was employed by GC-MS/MS.Chromatographic separation was performed on a DB-Innowax capillary column（30 m×0.25 mm×0.25 μm）.Pulse splitless injection mode was used and the injection volume is 1μL.The temperature program was set as：the initial temperature was 80℃，holding for 2 min，then 10℃/min up to 180℃，holding for 3 min，240℃ post run 6 min.Flow rate was 1.0 mL/min.The developed method showed good linearity in the range of 20 ng/mL-1 000 ng/mL for methyl carbamate（r=0.998 7），10 ng/mL-500 ng/mL for ethyl carbamate（r=0.999 9），respectively.The average recoveries of methyl carbamate and ethyl carbamate in liquid substrates were 78.4%and 100.20%，respectively.The average recoveries of methyl carbamate and ethyl carbamate in solid and semisolid substrates were 62.48%and 100.49%.The limits of detection were 6 μg/kg and 3 μg/kg respectively.The methods of simultaneous determination of methyl carbamate and ethyl carbamate in different substrates by GC-MS/MS is proved to be sensitive，specific stable and accurate.