Study Of The Determination Of Trace Metals In Seawater By Flow Injection ICPMS And Isotope Ratio By MC-ICPMS

Trace metals and their isotopes in seawater have important applications in the study such as tracing,water mass movement,climate change and environment protection.Hence,accurate measurement of the concentrations and isotope ratios of trace metals in samples with complex matrix like seawater,is the premise of their environmental study.In this thesis,methods using flow injection(FI)online coupled with ICPMS(FI-ICPMS)to determine the concentration of Ag,Re and rare earth elements(REEs)in seawater,and using MC-ICPMS to determine the isotope ratios of Ag,Ir and Os,were explored.The main contents and achievements were as follows:1.Methods using FI-ICPMS to detetmine Ag and Re in seawater were established,and successfully applied to seawater from Jiulong River Estuary and Taiwan Strait.The commercially available Dowex 1X8 anion exchange resin was the absorbant in the solid-phase extraction minicolumn which was embedded into an automately flow injection system developed in this study.The sample throughput and sample consumption of the methods were 7 h-1 and 7.5 mL,respectively;the detect limit,RSD and recovery were 0.06 ng kg-1,<3%and 91.3-109.7%for Ag,while 0.11 ng kg-1,<2%and 96.9-103%for Re.2.A method using FI-ICPMS to detetmine REEs in seawater was established,and successfully applied to seawater from Jiulong River Estuary,Taiwan Strait and East China Sea.The commercially available Toyopearl AF Chelate 650M chelate resin and the flow injection system in(1)were used in this study.The detect limit,RSD,recovery,sample throughput and sample consumption were 0.002-0.078 ng kg-1,<6%,82.7%-109.8%,11 h-1 and 6 mL,respectively.3.A combined standard-sample bracketing,internal(Pd)normalization and NIST SRM 978a Ag isotopic standard method to correct the mass bias occurred in the determination of Ag isotope ratio using MC-ICPMS,was optimized,and successfully applied to engineered and environmental samples.The concentration of Pd was 2 mg kg-1,and Ag concentrations in samples need not to match perfectly with standards,but to ≥5 μg kg-1.Ag in samples with complex matrix such as sediments and tissues was concentrated and separated by several AG 1X8 anion exchange columns.4.A combined internal standardization and state-of-art linear regression method to correct the mass bias occurred in the determination of Ir and Os isotope ratios using MC-ICPMS,was established,and successfully applied to the determination of the absolute isotope compositions of Ir and Os.The NIST SRM 997 Tl and 989 Re were chosen as the internal standards for Ir,and the calibrated Ir for Os.The analysis time for one data set were～15 min and～3 5 min for Ir and Os,respectively,which was achieved by simply changing the ICP radio frequency power to induce sufficient signal drift in short time,through which the method precision was enhanced.There was no need to match the concentrations of analyte and inteernal standards,and small amount of matrix had no effects.The measurement results of Ir were as follows:isotope ratio R(193/191Ir)=1.6866(5)k=1,isotope abundance X191=0.37221(8)k=1 and atomic weight Ar(Ir)=192.21763(15)k=1,which is the best Ir atomic weight measurement at present.Data from this study combined with the historical results,gave rise to a consensus data:R(193/191Ir)=0.5940(6)k=1 and Ar(Ir)=192.217(1)k=2,which was suggested as a revision of the current standard atomic weight,192.217(3)k=2 by IUPAC.The measurement results of Os were as follows:R(184/188Os)=0.00130(1)k=1,R(186/188Os)=0.11973(5)k=1,R(187/188Os)=0.1159(2)k=1,R(189/188Os)=1.2201(3)k=1,R(190/188Os)=1.9850(8)k=1 and R(192/188Os)=3.087(3)k=1;x184=0.000172(1)k=1,x186=0.015902(14)k=1,x187=0.015397(26)k=1,x188=0.132817(70)k=1,x189=0.162053(53)k=1,x190=0.263642(50)k=1 and x192=0.410017(185)k=1;Ar(Os)=190.2407(7)k=1.This study was the first independent determination of Os isotope composition since Nier(1937),and did not rely on Nier’s value.The high accuracy of the Os isotope data in this study was ensured by fully calibration,and the obtained data can be used as reference values.In addition,we present data on a new Certified Reference Material from NRC Canada IRIS-1 and OSIS-1 which fulfill the requirements of a delta zero references for Ir and Os isotope ratio measurements.