Abstract: Objective To establish a rapid and simple gas chromatographic-mass spectric method for qualitative and quantitative analysis of lidocaine in blood and cerebrospinal fluid(CSF). Methods Following an acidification of HCl , blood or CSF was alkalinized with NaOH (pH=9) and extracted with ether for two times. Evaporated in a water bath and with an air velocity of nitrogen gas, extract was dissolved with ethanol and analyzed by a gas chromatographic-mass spectrum method, lidocaine was analyzed qualitatively and quantitatively by GC/MS (SIM:86,58,72,87). Results Linear range of lidocaine detected in blood or CSF by this method is 1.0-60.0μg·mL-1(r=0.999 9), the minimum detected concentration of lidocaine was 0.02 μg·mL-1(S/N=3),recovery is at 85%-103%. This method was used in the determination of lidocaine in dog model died of the anesthesia with lidocaine. Conclusion This study provided a gas chromatographic-mass spectric analysis for lidocaine in blood and CSF. This method was more selective, little interferefering, more sensitivities and simpler. It could be used in the detection of lidocaine in biological fluids.[

Key words: lidocaine, gas chromatography-mass spectrometry, blood, cerebrospinal fluid