Comparative Study On The Contents Of 29 Elements In Postmortem And Living Person Blood

Objective:1.The qualitative and quantitative analysis methods for 29 elements in blood by inductively coupled plasma mass spectrometry(ICP-MS)was established.2.By measuring the content of 29 elements in the blood of non-metallic element poisoning death cases and healthy living venous blood,the content of each element in postmortem and living person blood were compared.Therefore,we determined which elements in the blood will be significantly increased due to postmortem redistribution(PMR).Simultaneously,we analyzed the effect of gender on the content of elements in postmortem blood,and the correlation between the content of elements in postmortem blood and the time interval from death to sampling.Methods:1.Detection methodThe ICP-MS detection method of 29 elements in blood was established,and the linear range,minimum detection limit,accuracy,precision and extraction recovery were verified.2.Sample collectionA total of 108 blood samples were collected from non-metallic elements poisoning death cases,and the time of death,the time of examination,the cause of death,the gender and age of the body were collected.Venous blood was collected from 100 healthy volunteers.3.Sample pretreatment and tested.250μL blood was precisely transferred to the sample tube,and 800μL 65%concentrated nitric acid and 200μL 30% hydrogen peroxide were added at the fume hood,closed for about 10 minutes.The sample tube was placed in the dry thermostat,and the parameter was set at 90℃ for 180 minutes.At the end of digestion,the sample tube was taken out and placed in the fume hood.After the digestion solution was reduced to room temperature,unscrewed the sample tube cover,the digestion solution was diluted to30 m L with distilled water,and then vortexed on the vortex oscillator for 30 s.About 3m L liquid was absorbed with a 5m L syringe and filtered by 0.22μm water polyether sulfone(PES)filter membrane,to be tested.4.Correlation between element content and time interval from death to samplingThe correlation between the content of elements in postmortem blood and the time interval from death to sampling was analyzed by statistical method.5.Comparison of 29 elements in the blood of postmortem and living personAccording to the measured values of 29 elements in the blood of living person,and combined with the existing literature reports on the content of elements in living person blood and human tissues and organs,the median,average,reference range(P5 ~ P95)and PM/AM ratio of 29 elements in postmortem blood and living person blood were analyzed and compared to determine which elements have the possibility of postmortem redistribution.Results:1.Establishment of ICP-MS detection method for 29 elementsThe ICP-MS method for the detection of 29 elements was established,and the linear regression equation,linear range and minimum detection limit were determined.The linear correlation coefficients of all elements were greater than 0.999,the accuracy was between 89% and 110%,the daytime and intra-day precision were less than 9%,and the extraction recovery was greater than 90%.2.There was a positive correlation between the contents of Mg,Mn,Cu,Zn and Cd in postmortem blood and the time interval from death to sampling.The analysis may be that with the prolongation of the time interval from death to sampling,the elements of the tissues and organs in the corpse have a longer time to redistribute,and eventually spread to the blood,resulting in an increase in the content.3.Among the 29 elements,the median content of Li,Mg,Al,Ca,Cr,Mn,Fe,Cu,Zn,As,Se,Rb,Zr,Cd,Sn,Cs,Ba and Pb in postmortem blood was higher than that in healthy blood.The ratio of PM/AM were all greater than 1.15.Analyzed the content of elements in tissues and organs,which may be caused by the decomposition and dissolution of tissues and organs after death,and the stored elements diffused into the blood along the concentration gradient.Conclusion:1.The ICP-MS method for the detection of elements in blood was established,which can simultaneously detect multiple elements with high efficiency,fast analysis speed and wide linear range,and can be better applied to forensic cases and scientific research needs.2.There was a positive correlation between the content of Mg,Mn,Cu,Zn,Cd and the time interval from death to sampling.It was clear that the contents of 18 elements Li,Mg,Al,Ca,Cr,Mn,Fe,Cu,Zn,As,Se,Rb,Zr,Cd,Sn,Cs,Ba and Pb,were significantly different in postmortem blood and living person blood,and the ratio of PM/AM were greater than 1.15,which had the possibility of postmortem redistribution.The reference range of 21 elements in postmortem blood was established.In the identification of death involving non-metal poisoning,it is not possible to determine whether the death is caused by metal poisoning only based on the content of elements in postmortem blood.Instead,a comprehensive analysis should be made based on the site of sampling,the time interval between the sample and death,the content of elements in tissues and organs,the manifestations of poisoning,pre-life contact history and medication history.