Research On Determination Of Trace Impurity Elements In High Purity Tungsten And High Purity Hafnium By ICP-MS After Matrix Separation

Inductively coupled plasma mass spectrometry(ICP-MS)is an inorganic mass spectrometry technique with low detection limit and simultaneous and rapid determination of multiple elements.When single quadrupole ICP-MS is used to determine Nb,Re in highpurity tungsten,and Ta,Pt,and Au in high-purity hafnium,each element is interfered by the compolex ion and doubly charged ion of matrix.It is necessary to use some methods to eliminate the interference in order to achieve accurate determination of the disturbed elements.In this paper,matrix separation and various experimental conditions were explored,and a detection method of matrix separation-ICP-MS for the determination of trace impurity elements in high-purity tungsten and high-purity hafnium was established.The tungsten matrix was separated by lead tungstate precipitation.The experimental conditions were studied,such as sample dissolution reagent,precipitant dosage,acidity,precipitation temperature,heating time and internal standard element.The optimized conditions were as follows:dissolve sample with nitric acid-hydrofluoric acid mixed acid,the precipitation temperature was 95?,2.7 mL of 10 mg/mL lead acetate solution was added dropwise and heated continuously for 5 min,the whole separation cycle was about 10 min;Cs was chosen as the internal standard for determination.The established method is simple and rapid,the residual amount of tungsten was less than 1 ?g/mL,the quantification limits of Nb and Re were 0.023 ?g/g and 0.12 ?g/g,respectively,and the recoveries were 94%?108%.The RSD of spiked samples were 0.7%?6.7%.The hafnium matrix was separated by the hafnium hydroxide precipitation,and the experimental conditions were studied,such as the amount of hydrofluoric acid,acidity,and standing time.The optimized conditions were as follows:ammonia water(1+1),stand for 10 min;the whole separation cycle was about 20 min,the residual hafnium was less than 5 ?g/mL;the limit of quantification of Pt was 0.24 ?g/g,the recovery was 102%,and the RSD was 4.8%.The hafnium matrix was separated by the ion exchange method,and the experimental conditions were studied,such as the acidity of the upper(elution)column,the elution flow rate,the concentration of the eluent,the elution flow rate,and the injection volume.The optimized conditions were as follows:the upper(elution)column was 10%(V/V)HNO3-5%(V/V)HF solution,the elution flow rate was 1 mL/min,the Ta eluent was 10 mL 2 mol/L NH4Cl-2 mol/L NH4F solution,the eluent of Pt and Au was 20 mL of 60 g/L thiourea hot solution,the elution flow rate was 2 mL/min,the injection volume is 10 mg,and the whole separation cycle was about 50 min;the residual amount of hafnium in the Ta eluent was less than 5 ?g/mL,and that in the eluent of Pt and Au was less than 0.5 ?g/mL.The limits of quantification of Ta,Pt and Au were 0.85 ?g/g,0.72 ?g/g and 1.1?g/g,respectively,and the recoveries were 82%?109%,the RSD of spiked samples were 2.6%?13%.For the determination of trace amount of Pt in high-purity hafnium samples,the precipitation method is simple and efficient,and has a low limit of quantification,which is superior to the ion exchange method.In this paper,two matrix separation methods were used to solve the problem of mass spectrometry interference in the determination of trace impurity elements in high-purity tungsten and high-purity hafnium by single quadrupole ICP-MS,a corresponding quantitative analysis method was established.The results were compared by the inductively coupled plasma tandem mass spectrometry(ICP-MS/MS)method,the results of F-test and t-test showed that determination results of two methods had no significant difference(?=0.05).Because of the completion of this method,the application range of single quadrupole was further expanded,and a reference for solving similar mass spectrometry interference was provided.