The Study Of Estimating Exposure Time Of Toxic Elements By LA-ICP-MS

Recently,the abrupt-and-major public security events resulting from toxic elements occurred frequently,which caused serious adverse effects.As a result,researches on toxic elements have become hot topics in various fields,such as public health and society.However,the estimation of exposure time of toxic elements is always a difficult issue in the field of toxicological analysis.Due to the low spatial resolution,lacking of reliability and accuracy is the main defect for conventional methods.Therefore it is difficult to meet the requirement of practical application.Because of its analytical merits of real time and in situ,laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)can perform a dot-matrix analysis of toxic elements in individual hair strands from micro-system level and effectually improve the defect of low spatial resolution for conventional methods.According to the status and conditions,a new strategy for estimating exposure time of toxic elements with better accuracy was proposed.The characteristic of spatial distribution of toxic elements in single hair strands was studied by LA-ICP-MS.The core retention position of toxic elements in the hair shaft was identified by the spatial distribution.The exposure time of toxic elements was estimated by the hair length which corresponding to the core retention position of toxic elements combining with the hair growth rate.As showed below,the contents of this study can be divided into 2 parts.Chapter 1:The study of quantitative analysis of arsenic and lead in single hair strands by LA-ICP-MSAs the two common toxic elements,arsenic and lead were regarded as the objects of the study.A matrix matching hair conference materials with inorganic elements of various concentration gradients was developed,and the quantitative analysis method of arsenic and lead in single hair strands by LA-ICP-MS was established.Afterwards,the validation of methodology was conducted.The validation results showed that this method satisfied with the requirements of analysis of good linearity,high sensitivity and a low limit of detection(LOD).The linear correlation coefficients were greater than 0.99,the LOD for arsenic and lead were 3.19?g/g and 1.07?g/g,and the LOQ for arsenic and lead were 6.91?g/g and 3.21?g/g.The accuracy varied from 90%to 108%,and the precision ranged from 1.4%to 5.6%.This quantitative method provided the technological support for estimation of exposure time of arsenic by single hair strands.Chapter 2:The estimation of exposure time of 75 As by single hair strandsHair samples of occipital region were obtained from acute promyelocytic leukemia(APL)and the concentration of arsenic was determined by the quantitative analysis methods.The characteristic of spatial distribution of As was studied by the variations of arsenic concentration along the hair shaft,the results showed that there was no large diffusion of arsenic along the hair shaft with time.The hair growth rate was determined by the systematic distribution of arsenic along the hair shaft.The exposure time of As was estimated by the hair length which corresponding to the variations of arsenic concentration in single hair strands combining with the estimated hair growth rate.The actual time of treatment for patient was regarded as the reference values,and the estimated time was considered as the measured values.Afterwards,the validation of the methods was conducted by these two values.The results showed that this method could not only make the estimation in the interval of days,but also effectually controlled the error of the estimated results and improved the accuracy with the biases were both less than 20%.This study provided a novel research approach for estimating the exposure time of other toxic elements.