Quantitative Analysis Of Trace Elements In High Purity Gold By Laser Ablation Inductively Coupled Plasma Mass Spectrometry

High purity gold has been widely used in electrical resistance measurement,aircraft,missile,rocket brazing filler metal,gold medicine,night vision and other fields,and various impurity elements will affect its physical and chemical properties,so it is necessary to accurately determine the content of these impurity elements.Laser denudation-plasma mass spectrometry(LA-ICP-MS)is an in-situ,micro-area and trace element analysis technique developed rapidly at the beginning of this century.LA-ICP-MS can realize solid-state injection,and can largely avoid the interference of some polyatomic ions caused by solution injection.Highpurity gold is expensive,and the standard samples are not easy to obtain.But high purity copper is similar in physical and chemical properties and the standard samples are easy to obtain.Therefore,this paper first chooses pure copper as the research objective,and obtains the relative sensitivity factor(RSF)of each element.Then the relative sensitivity factor obtained is used to correct trace impurity elements in high purity gold determined by LA-ICP-MS.Firstly,this paper uses LA-ICP-MS to determine trace impurity elements in pure copper.The working conditions of the laser denudation instrument were optimized.The laser energy was 100%.the laser scanning rate was 50 um/s,the denudation aperture was 200 um,and the carrier gas velocity was 0.4 L/min.The relative sensitivity factor RSF of elements was determined according to the standard values of high purity copper standard samples.The detection limit of each element was 0.0065 ug/g-0.31 ug/g by calculating the ratio of 3 times standard deviation of 11 carrier gas blank signal values to the signal values of matrix elements.RSD of the method was 2.8%?14%.At the same time,according to the national standard method-Inductively coupled plasma mass spectrometry(ICP-MS),the content of impurity elements in high-purity copper was determined.The results obtained by LA-ICP-MS and ICP-MS were compared by means of average consistency test.There was no significant difference.The trace impurity elements in high purity gold were determined by LA-ICP-MS.The laser parameters for measuring pure gold are determined as 100%laser energy,20 Hz laser pulse frequency,200 micron laser ablation aperture,60 micron/s laser ablation rate and 0.4 L/min carrier gas velocity.Under the selected optimum parameters,pure gold samples were determined five times in parallel by time-resolved mode.According to the relative sensitivity factor RSF of impurity elements in pure copper,the results were corrected.The contents of trace elements ranged from 0.0065 ug/g to 0.29 ug/g,and the relative standard deviation ranged from 3.8%to 21%.Compared with the results of ICP-MS and GDMS,the method has better consistency.The feasibility of using pure copper reference material to obtain relative sensitivity factor in correcting the results of pure gold analysis is discussed.The results show that LA-ICP-MS method has the advantages of low detection limit,high sensitivity,fast analysis speed,real-time and micro-analysis.For other non-ferrous metals which are difficult to obtain standard samples,it has reference significance.