Abstract: Objective To develop a method for determination of meropenem concentration in human plasma by liquid chromatograph tandem mass spectrometry (LC-MS/MS), and to apply it to  therapeutic drug monitoring in intensive care unit（ICU） patients with sepsis. 
Methods The Kinetex-C18 100A column (2.6 μm, 4 mm× 50 mm) was used, and the mobile phase consisted of methanol-1‰ methanoic acid solution (60〖DK〗∶40, v/v), the flow rate of 0.4 mL/min, the column temperature of 40 ℃ and the injection volume of 3 μL. Carbamazepine was used as internal standard, and electron spray ionization (ESI) source was applied and operated in multiple reaction monitoring (MRM) mode. The quantitative analysis transitions were m/z 384→141 (meropenem) and m/z 237→194 (carbamazepine). The method was applied to 197 ICU patients with sepsis for therapeutic drug monitoring. 
Results The linearity was good for meropenem in human plasma within the range of 0.02-30 mg/L. The calibration curve was y=4.934×10-5x+2.083×10-2 (r=0.999 9). The relative standard deviation (RSD) of intra- and inter-precision was less than 3%, and the extraction recovery was 91.96%-100.97%. The range of plasma concentration of meropenem in 197 sepsis patients was 0-16.33 mg/L. 
Conclusion The method for determining meropenem concentration is simple, fast, sensitive, specific and accurate, which can be used for the therapeutic drug monitoring in patients with sepsis. 

Key words: sepsis, meropenem, liquid chromatography tandem mass spectrometry