Study On Judgment Method Of Qualitative Analysis Results Of Common Drugs In Urine By GC-MS

In general,the problem of drugs abuse in China is still spreading.To test common drugs,the forensic poison analysis laboratory mainly use gas chromatography-mass spectrometry(GC-MS).At present,the qualitative analysis of drugs by GC-MS is mainly based on retention time and ion abundance ratio.Because different substrates have different effects on the target peak time,signal/noise and ion abundance ratio,the criteria for qualitative judgment will be different.When the concentration of drugs is close to the detection limit,the difficulty of qualitative judgement is greatly increased,and sometimes there will be mistakes in the biological samples of complex matrix such as urine,blood and tissue with low content of the target substance.Therefore,the judgement of qualitative indicators is very important.In recent years,some newly issued technical specifications have adopted the international popular quality control standards,but most of them are guidance documents without reliable experimental data support.This article established a GC-MS analysis method for simultaneous detection of 6 drugs in urine,including methamphetamine,MDMA(3,4-methylenedioxymetamphetamine),meperidine,ketamine,methadone,cocaine.Different urine sample matrices and different concentrations were detected by established methods in the GC-MS full scan mode(SCAN),selective ion monitoring mode(SIM)and multiple reaction monitoring mode(MRM).We obtained chromatograms and mass spectra of six drugs.We got the retention time and ion abundance ratio to make a quantitative judgement standard for poison analysis.Our experiment results and data analysis provided data support and reliable assurance for the accurate identification of common drugs in urine.1.The paper aimed to establish a GC-MS analysis method for six drugs(methamphetamine,MDMA,meperidine,ketamine,methadone,cocaine)in urine.By selecting the suitable solvent and optimizing the pH value,a simple and clean pretreatment method of the extract was obtained.1 mL urine was collected,20?L of internal standard solution(100?g/mL),15?L of 10%NaOH solution and1 mL cyclohexane were added,mixed by ultrasound for 10 min,centrifuged for 5 min,and 200?L supernatant was transferred to the sample vial.The vials were scanned in SCAN,SIM,and MRM modes.Six drugs have a good linear relationship.Correlation coefficient(R~2)were all greater than 0.99.The lowest detection limit was between 0.10 to 0.30?g/mL(scan);0.02 to 0.10?g/mL(SIM);0.01 to0.30?g/mL(MRM).The quantitative limit was between 0.30 to 0.90?g/mL(scan);0.06 to 0.30?g/mL(SIM);0.03 to 0.90?g/mL(MRM).The recovery rate was between 76.6%to 90.9%,and the intra and inter day precision were between 0.21%to 11%.2.The paper aimed to investigate the maximum allowable deviation of qualitative judgement factors under the three GC-MS modes of six drugs.The established GC-MS analysis method was used to detect various urine drug samples,and thousands of chromatograms and mass spectrograms were obtained.The data were extracted by Matlab software and analyzed by SPSS software,and the maximum deviations of absolute retention time and relative retention time obtained from GraphPad Prism were:?0.04 min,?0.5%(scan);?0.02 min,?0.5%(SIM);?0.02 min,?0.4%(MRM).The absolute and relative deviations of ion abundance ratios were:?20%,?50%(scan);?20%,?50%(SIM);?20%,?25%(MRM).3.By comparing with the qualitative results of real samples,the reliability of the judgement method was verified.The established method was used to test the urine samples of 16 drug addicts.The retention time and ion abundance ratio deviations were all within the range of the judgement method established in this paper,which verified the reliability of this method.