【摘要】：本研究建立了陽離子交換樹脂分離鉻元素的化學流程和多接收器電感耦合等離子體質(zhì)譜儀鉻同位素分析方法。在分析過程中,采用50Cr-54Cr雙稀釋劑法對化學分離和質(zhì)譜分析過程中產(chǎn)生質(zhì)量分餾進行校正。本研究采用AG50W-X8陽離子交換樹脂,經(jīng)過兩次化學分離,將純橄巖、玄武巖和頁巖中的鉻與基質(zhì)元素分開。第一次化學分離鉻元素的回收率約90%,第二次的回收率為98%,總回收率約為90%。研究發(fā)現(xiàn),玄武巖和頁巖樣中的Al、Ti元素會在樹脂中出現(xiàn)過載現(xiàn)象,因而提前被洗脫,經(jīng)過第二次化學分離后,可以將Al、Ti等元素進一步的除去。經(jīng)過兩次化學分離后,樣品中的Ti/Cr小于5.3×10-4,V/Cr小于2.5×10-4,Fe/Cr小于2.4×10-4。Al、Ti和V的基質(zhì)效應研究表明,樣品純化后含有極少量的Ti、Fe、V,不會影響樣品的Cr同位素組成。經(jīng)The double-spike軟件模擬計算,雙稀釋劑的最優(yōu)組成為50Cr/54Cr=1.41;樣品與雙稀釋劑的最佳混合質(zhì)量比例為28.33:71.67。實際標定的雙稀釋劑組成為50Cr/54Cr=1.74。采用雙稀釋劑法校正儀器的質(zhì)量分餾,NIST SRM979自測的長期重現(xiàn)性為δ~(53)Cr(‰)=0.00±0.06(2SD,N=20)。NIST3112a相對于NIST SRM979的結(jié)果為δ~(53)Cr(‰)=-0.05±0.07(2SD,N=8)。NIST3112a的結(jié)果與已發(fā)表的結(jié)果在誤差范圍內(nèi)一致,且精度相當。以NIST SRM979為標準,玄武巖標準樣品BIR-1a和BHVO-2的鉻同位素組成δ~(53)Cr(‰)分別為-0.16±0.11(2SD,N=5),-0.19±0.11(N=10,2SD),該結(jié)果與已發(fā)表的數(shù)據(jù)在誤差范圍內(nèi)一致。純橄巖標準DTS-2b的鉻同位素組成為δ~(53)Cr(‰)=-0.05±0.11(N=4,2SD),其結(jié)果在硅酸鹽地球范圍內(nèi)。實驗室內(nèi)部黑色頁巖標準樣品CAGS-BS的鉻同位素組成結(jié)果為δ~(53)Cr(‰)=0.2±0.11(N=6,2SD)。實驗結(jié)果表明本論文所建立的鉻同位素分析方法適用玄武巖、純橄巖及黑色頁巖。
[Abstract]:The chemical process of separation of chromium by cation exchange resin and the method of chromium isotope analysis by multi-receiver inductively coupled plasma mass spectrometer have been established in this paper. In the process of analysis, 50Cr-54Cr double diluent method was used to correct mass fractionation in chemical separation and mass spectrometry. In this study, AG50W-X8 cation exchange resin was used to separate chromium from matrix elements in pure olivine, basalt and shale after two chemical separations. The recovery of chromium was about 90 for the first chemical separation, 98 for the second, and about 90 for the second. It is found that the Alnti element in basalt and shale samples will be overloaded in the resin, so it can be eluted in advance. After the second chemical separation, Alnti and other elements can be further removed. After two chemical separations, the substrate effect of Ti/Cr < 5.3 脳 10 ~ (-4) V / Cr < 2.5 脳 10 ~ (-4) Fe / Cr < 2.4 脳 10 ~ (-4) Al _ (4) Ti and V was studied. The results show that the sample contains a very small amount of Ti _ (10 ~ (-4) Fe _ (10) V, which will not affect the Cr isotopic composition of the sample. The results of The double-spike software show that the optimum composition of the double diluent is 50Cr / 54CrN1.41, and the optimum mass ratio of the sample to the double diluent is 28.33: 71.67. The actual calibrated double diluent composition is 50Cr / 54CrN 1.74. The long-term reproducibility of NIST SRM979 self-determined by using double diluent method is 未 ~ (53) Cr (鈥，

本文編號：2161421