Benzodiazepines are one of the most frequently prescribed drugs with a broad range of therapeutic effects,including sedative hypnotic,anxiolytic,muscle relexation and anticonvulsant.However,the potential possibility for addiction and abuse in both clinical and forensic cases greatly increased due to the high consumption of benzodiazepines all over the world.For this reason,it is essential to develop a rapid and accurate approach for the determination of benzodiazepines.In this paper,a method was developed for the detection of eight representative benzodiazepines,including diazepam,nitrazepam,clonazepam,flunitrazepam,lorazepam,alprazolam,estazolam,and midazolam in blood samples by high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry(QTRAP HPLC-MS/MS).Brief steps for the method construction are described as follows.Firstly,the MS/MS library of target analytes with three collision energies were established for the searching and fitting of suspicious detected compounds.Secondly,the instrument conditions were optimized,with Phenomenex Kinetex Biphenyl(100 mm×30 mm,26 μm) as the column for separation,and 5 mmol/L ammonium acetate containing 01% formic acid and methanol as mobile phases for gradient elution.Finally,different pretreatment methods for blood samples,including liquid-liquid extraction using organic solvent,and protein precipitation using methanol or acetonitrile were compared,and the method of acetonitrile protein precipitation was selected owing to the convenience in handling and its relatively high recoveries for target analytes.With the optimized parameter and condition,the blood samples were firstly processed by the acetonitrile protein precipitation method,then centrifuged to obtain the supernatant,and finally filtered for analysis.Scheduled multiple reaction monitoring combined with information dependent acquisition and enhanced product ion(sMRM-IDA-EPI) scanning mode with electrospray ionization(ESI) under the positive condition was applied to data acquisition,with which the suspicious detected compounds could be confirmed by EPI library searching,and quantitative analysis could be carried out with external standard method according to sMRM data.Eight benzodiazepines showed good linear relationships in the concentration range of 05-50 ng/mL with their correlation coefficients(r) larger than 0998.The limits of detection(LOD,S/N≥3) for eight benzodiazepines were in the range of 001-010 ng/mL,while the limits of quantitation(LOQ,S/N≥10) were 010-025 ng/mL.Recoveries for eight compounds at three spiked levels of 10,50 and 20 ng/mL ranged from 793% to 112%,with matrix effects of 798%-972% and relative standard deviations of 43%-11%.Owing to the simple steps of the experiment,the entire process could be completed with reliable and accurate results.The established method was successfully validated by its application in the benzodiazepines screening of a blood sample from the local emergency department.Three compounds of diazepam,alprazolam and midazolam were detected and confirmed,with their concentrations of 3057,651 and 6869 ng/mL,respectively.This method is suitable for rapid diagnosis and condition evaluation of poisoning patients,and provides a technical support for medical emergency and poisoning detection.