Detection And Accumulation Of Rare Earth Elements In School-age Children In Jiaxing City

In recent years,more and more attention was paid to rare earth element pollution,which had been included in the national risk monitoring program.As the end of the food chain,the accumulation of rare earth elements in human body could best reflect the current situation.At present,there is no accurate or unified national standard for the detection of rare earth elements in biological samples.For this purpose,this paper aims at establishing a detection method for rare earth elements in human biological samples(saliva and hair samples)by ICP-MS.The biological samples of school-age children were tested and the results provided data support for the establishment of the normal value database of rare earth elements in human biological samples,the main research topics are as below:1)Method for 16 rare earth elements in saliva samples by ICP-MSA quantitive method was established by optimizing the pretreatment and conditions of ICP-MS.Samples were directly diluted with 1%nitric acid when 103Rh,185Re were used as the internal standards to eliminate matrix interference and collision reaction cell was used to eliminate mass spectrum interference.Under optimized experiment condition,the sixteen elements has good linearity during 0.5?100 ?g/L(r=0.9995?0.9999)and the satisfactory recoveries between 82.4%?12.0%(n=6).The limit of detection and limit of quantitation were 0.011-0.068 ?g/L and 0.037?0.227 ?g/L,respectively.The result showed that the method was fast,accurate and effective,which was suitable for simultaneous determination of the sixteen elements in saliva samples.Furthemore,the paper provided a new way for the investigation and diagnosis of rare earth element inside the human body.2)Method for 16 rare earth elements in human hair samples by ICP-MSThe method by ICP-MS was proposed after optimizing the pretreatment and the method conditions.Nitric acid-hydrofluoric acid(10+2)were chosen as the digestion system,meanwhile the automatic graphite digestion instrument was applied as the pretreatment equipment.Through optimizing the parameters such as oxide,double charges and sensitivity,103Rh and 185Re were used as the internal standards to reduce matrix interference and DRC(NH3 reaction)mode was used to eliminate mass spectrum interference.Under optimized experiment conditions,the sixteen elements have good linearities during 0.1?10 ?g/L(r=0.9995?0.9999)and satisfactory recoveries between 86.6?110.5%(n=6).The limit of detection and limit of quantitation were 0.12?1.90 ?g/kg and 0.41?6.34 ?g/kg,respectively.Human hair standard numbered GBW07601 was selected for the method verification,which showed relative standard deviation between 3.25-7.14%.This method was superior in low detection limit,good accuracy and high precision,and suitable for rapid detection of rare earth elements in human hair samples.3)Statistical analysis and reference range method for the content of rare earth elements in saliva and hair of school-age childrenThe reference range of normal values in saliva and hair samples of school-age children in Jiaxing city was determined by P5-P95 percentile method.The results of rare earth detection of different genders and different age groups were statistically analyzed by mean value,median,one-way analysis of variance and nonparametric rank sum test.The results showed that:a.There was no significant difference in the concentrations of rare earth elements in the saliva of children of different genders;b.The concentrations of Sc,Y,La,Ce,Pr,Nd and Sm in saliva of children of different ages were positively correlated with age;c.There were significant differences in the concentrations of three rare earth elements(Nd,Sm,Gd)in the hair samples of children of different genders;d.The concentrations of five rare earth elements(Sc,Y,La,Ce,Nd)was positively correlated with age in the hair samples of children of different ages.According to the concentrations checked out,six rare earth elements including Sc,Y,La,Ce,Pr and Nd,were relatively high in saliva and hair samples.Among these elements,the Ce was of the highest.