Research of Isotopic Reference Material for Improvement of Measurement Precision of Isotopic Ratios in Space and Earth Sciences

钕同位素标准要求杂质含量低。此外，(1)由于日本普遍研究的岛弧样品具有较高的Nd值，因此应具有较高的Nd值；(2)由于Ce和Sm的同位素干扰减少，应具有较低的稀土杂质。对由SPEC、JMC、CERAC、默克、信越和三和六家化学公司制备的高纯氧化钕进行了同位素比值和稀土杂质的检测。最好是信越公司的试剂。从Shinetsu公司购买了两瓶氧化钕试剂，每瓶重1公斤，定义为Split 1和Split 2。Split 1的上部被丢弃。在11个研究所的12台质谱仪上循环测量JNdi-1和LaJolla-ND的同位素值，采用…方法测定了JNdi-1和LaJolla-ND的同位素比除使用归一化值外，其余&lt；@D1143@&gt；D1Nd/&lt；@D1144@&gt；D1Nd=0.7219.18位置分别测量2~12次。通过循环测量的jNdi-1和LaJolla-ND的值分别定义为A和B，并且根据这两个值F&lt；@D2n@&gt；D2=2A&lt；@D2n@&gt；D2/(B&lt；@D2n@&gt；D2+B&lt；@D2n+1@&gt；D2).计算F(因数)值同一研究所同一仪器、同一程序所测得的多个位置的F值在其标准偏差范围内一致(2sigmam)。因此，1公斤瓶中试剂的同位素组成被认为是均一的。这允许计算所有18个位置的F值的平均值，即1.000503(]sy+-。[)1(1sigmam)。JNdi-1的同位素比值为0.512114(Sy.+-)，相当于LaJolla-ND的0.511857。[)7.此外，为了考虑&lt；@D1142@&gt；D1Nd；D1Sm衰变产生的&lt；@D1142@&gt；D1Nd；D1Sm，即已灭绝的核素&lt；@D1142@&gt；D1ND/&lt；@D1144@&gt；D1Nd比值的作用，还检查了JNdi-1的&lt；@D1142@&gt；D1Nd；D1Nd值。从104个数据的结果可以看出，F值的平均值为1.000006(]sy.+-。[)3(1西格曼)。这表明JNdi-1和LaJolla-ND的值没有显著差异。日本地质调查局已经开始分发新的同位素标准试剂(JNDI-1)。较少

Neodymium isotopic standard requires low impurity. In addition, (1) it should have a high ^<143>Nd/^<144>Nd ratio because of high ratios in island-arc samples generally researched in Japan and (2) should have low rare-earth impurities because of the reduction of isobaric interference by ^<142>Ce and ^<144>Sm. Isotopic ratios and rare-earth impurities were examined in high purity neodymium oxides prepared by six chemical companies, SPEC,JMC,CERAC,MERCK,ShinEtsu and Mitsuwa. The reagent of the ShinEtsu company is preferable. Two bottles of 1kg each, of neodymium oxide reagent from the same lot, were bought from the ShinEtsu company and defined as split 1 and split 2. Upper part of split 1 was discarded. The rest was divided into 725 small bottles, each of them containing 1g reagent, from upper part (position 1) to lower part (position 725) in order.Isotopic ratios of JNdi-1 and LaJolla-Nd were determined by cyclic measurement on 12 mass spectrometers in 11 institutes using specific proce … More dures, except for the using of normalized value, <@D1143@>D1Nd/<@D1144@>D1Nd=0.7219.18 positions of JNdi-l were measured twice to twelve times, respectively. The values of jNdi-1 and LaJolla-Nd by cyclic measurement are defined as A and B,respectively, and F (Factor) vaoues are calculated from the two values, F<@D2n@>D2=2A<@D2n@>D2/(B<@D2n@>D2+B<@D2n+1@>D2). F values of several positions measured by the same instrument and the same procedure in one institute are consistent in the range of their standard deviation (2sigmam). Therefore, the isotopic composition of the reagent in the 1kg bottle is considered to be homogenous. This allows to calculate an average of F values of all 18 positions, that is 1.000503(]SY.+-。[)1 (1sigmam). The isotopic ratio of JNdi-1 which corresponds to 0.511857 of LaJolla-Nd is 0.512114(]SY.+-。[)7. Moreover, to consider the role of standard for variation of <@D1142@>D1Nd produced by decay of <@D1146@>D1Sm, that is the extinct nuclide, <@D1142@>D1Nd/<@D1144@>D1Nd ratios of JNdi-1 were also checked. From the results of the 104 data, it is found that the average of F values is 1.000006(]SY.+-。[)3 (1sigmam). This indicates that the values of JNdi-1 and LaJolla-Nd do not have a significant difference. Geological Survey of Japan has started to distribute the new isotopic standard regent (JNdi-1). Less