关键词:
ammonium fluoride
hafnium
inductively coupled plasma mass spectrometry(ICP-MS)
matrix modifier
niobium
tantalum
zirconium
摘要:
The accurate determination of high field strength elements (HFSE) in geochemical exploration samples such as hafnium(Hf) ,niobium(Nb) , tantalum(Ta) and zirconium(Zr) is the important prerequisite for achieving information on the diagenetic evolution of rocks. In this study,the solid melt digestion method using ammonium fluoride was combined with the sensitization technology using triethylamine as the matrix modifier. The method for the determination of Hf,Nb,Ta and Zr in geochemical exploration sample by inductively coupled plasma mass spectrometry (ICP-MS) was established. The pretreatment of sample had two steps. Firstly,the sample was melted with ammonium fluoride at 240 °C for 2. 5 h,where the mass ratio of ammonium fluoride and sample was 6 : 1. Then,certain amount of perchloric acid were added to dissolve the sample. After evaporation,the nitric acid and a small amount of hydrochloric acid was added for redisso-lution-evaporation,realizing the complete digestion of sample. After evaporating the solution to almost dry-ness,the residue was redissolved with nitric acid. 2% (volume fraction, the same below) nitric acid-0. 2% hydrofluoric acid was added as the determination medium to avoid the hydrolysis or polymerization of Nb and Ta. 10% triethylamine was used as matrix modifier for determination. The normalized signal intensity of Hf,Nb,Ta and Zr increased by 1. 8,12. 5,2. 9 and 3. 3 times, respectively. The linear correlation coefficients of calibration curves of elements were all higher than 0. 999. The limits of detection of method were between 2. 23 and 22. 7 jng/kg,and the limits of quantification were between 7. 43 and 75. 8 jug/kg. The contents of Hf,Nb,Ta and Zr in certified reference materials of soil, rock and stream sediment were analyzed according to the experimental method. Each sample was determined for 12 times in parallel. The results showed that the measured values were basically consistent with the certified values. The logarithmic deviations(