Study On Determination Of Heavy Metals In Biological Samples By Inductively Coupled Plasma Mass Spectrometry

Polluted environment by heavy metal and related health problems received extensive concern of the society in recent years. Heavy metal pollution has the characteristic of long-term, cumulating, concealment and irreversibility. People are exposured to heavy metal through air, water and food. Human biomonitoring of heavy metals is of great significance to evaluate the health status and to develop the medical diagnosis standards and environmental hygiene standards. Inductively coupled plasma mass spectrometry (ICP-MS) has advantages of lower detection limit, high sensitivity, simultaneous multi-element analysis, which is suitable for human biomonitoring of heavy metals. The purpose of this thesis is to establish detection method for heavy metal elements in human urine and blood by ICP-MS to provide the beneficial experiences for the heavy metal biomonitoring method development. The main research contents and results are as follows:1.10-fold dilution by1%HNO3was applied as pretreatment method to prepare large quantities of urine samples.52Cr,55Mn,59Co,6Ni,75As,114Cd,121Sb,202Hg,208Pb were identified by isobaric interference analysis and adduct interference analysis with the principles of selected nuclides in mass spectrometry.72Ge,115In,209Bi were selected to be internal elements to calibrate the matrix effect. Dynamic reaction cell technology (DRC) was used to eliminate the interferences. Quantitative method was developed for the analysis of multi heavy metal elements in urine samples. The correlation coefficient of the calibration curves are larger than0.999in the range of0.11～10.0μg/L. The limit of detections(LODs) were0.07μg/L(Cr),0.08μg/L(Mn),0.03μg/L(Co),0.15μg/L(Ni),0.26μg/L(As),0.06μg/L(Cd),0.13μg/L(Sb),0.18μg/L(Hg),0.23μg/L(Pb). The spiked recoveries were in the range of93.5%～128.9%. The value of urine reference material determination is accordant with the value of standard with intra-day precision in the range of3.0%～5.2%and inter-day precision in the range of3.2%～12.6%.2. The effect of eliminating the memory effect of Au solution on Hg was studied. Experiments showed that, the clearance effect of Hg was best when pAu:pHg=10:1in the solution. As a result, Au was added to the sample solutions with internal standards to reduce the memory effect of Hg.3.The water bath digestion pretreatment method of whole blood samples were developed through optimizing the digestion reagent and time. The component of digestion reagent is500μL nitric and200μL hydrogen peroxide. By heating in boiling water bath for2hours, sample digestion is complete and the measurement result is satisfactory. Sample pretreatment efficiency is greatly improved compared with the microwave digestion method, making it more suitable for the determination of bulk samples.4. Quantitative method was developed for the analysis of Mn, Co, Cd, Sb, Hg, Pb of whole blood samples. The correlation coefficient of the calibration curves are larger than0.999in the range of0.43-10μg/L. The limit of detections(LODs) were between0.13(Co)-0.38(Hg) μg/kg.The spiked recoveries were in the range of83.1%-111.7%with the relative standard deviations less than7.9%, which basically meet the requirements of determination.5.Matrix-match calibration method was tried in urine sample analysis. The experiental results showed that, the accuracy of the As determination was improved in ICP-MS stand mode. For Cd, Sb, Hg, Pb, the determination results showed no great difference. The interference was not eliminated by matrix match calibration and collision/dynamic reaction cell technology was still needed. As urine sample matrix is complicated and samples are various, the matrix is difficult to match. The related further research are needed to better the method.6. Isopropanol was used to match the standard curve as signal enhancer and experimental results showed that all elements’ signal intensities were enhanced when1%(v/v) isopropanol was added. As the concentration of isopropanol increased, signal intensities decreased instead,except for Cr. When2%(v/v) isopropanol was added, the signal intensitiy of Cr and As had great improvement while the signal intensitiy decreasing of other elements was little. So2%(v/v) isopropanol was used to enhance the As singal to get better accuracy. But its accuracy and stability still need further experimental verification.