BACKGROUNDDetermination of strontium (Sr) and neodymium (Nd) isotopic composition in geological samples by Multi-collector Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) needs a lengthy and complex chemical preparation procedure. Moreover, samples cannot be dissolved completely.

OBJECTIVESTo effectively digest samples and eliminate interferences from the experimental process.

METHODSGeological samples were dissolved by microwave digestion. The processes of Sr, Nd chemical separation and mass spectrometry analyses were studied. In particular, the recovery and memory effect of resin column were investigated.

RESULTSThe research shows that after ten times usages Sr and Nd procedure, blanks of the resin are less than 1.0 ng. However, the recovery decreases significantly from 98% to 20% and 90% to 50%, respectively. If the analyzed samples contain low concentrations of Sr and Nd, which are insufficient for mass spectrometry analysis, it is suggested that Sr special effect resin should be used no more than 5 times and AG50W-X8 and Ln resin should be used no more than 10 times. The entire procedure is applied in the separation of Sr and Nd of international standard geological samples (BCR-2, W-2a, BHVO-2, AGV-2). The acquired ⁸⁷Sr^/86Sr and ¹⁴³Nd/¹⁴⁴Nd ratios are consistent with those in the literature, and the instrumental internal precision 2SE (n=50) and methodological external precision 2SD (n=6) are better than 0.0015%.

CONCLUSIONSThe proposed method meets the requirement of high-precision measurement of Sr and Nd isotopic composition in geological samples.