HIGH PERFORMANCE SYRINGE BASED DESOLVATION SYSTEM FOR MC-ICP-MS

Large database of high-precision isotope ratio measurements (Sr, Nd, Pb, U, etc) are required in a wide variety of disciplines (geology, archaeology, anthropology, hydrology, forensics, etc) for both source tracing and understanding geochemical cycles. As a result, high throughput analysis is becoming increasingly important for many applications of radiogenic and non-traditional metal isotopes.
Here we evaluate the combination of the microFAST-MC and apex desolvating nebulizer (ESI, Omaha, USA), high-throughput sample introduction system on a NEPTUNE Plus MC-ICP-MS, with Jet Interface option and 1013  amplifier for highest sensitivity. The dual loop injection system, syringe loads sample into one loop while syringe injecting sample from the other loop to the nebulizer. Alternating loop injections avoids overhead associated with sample uptake and washout during conventional self-aspiration. This provides very efficient sample handling for a wide range of sample volumes (10s to 100s of µl) increasing both sample utilization and sample throughput. The NEPTUNE Plus sensitivity has been improved through the combination of high-efficiency inlet systems and sampling interfaces to the point that small (ng) samples can be measured at sub-epsilon unit precision.
One application requiring large datasets is the GEOTRACES programme. High-precision 143Nd/144Nd isotope ratio measurements are essential for tracing and understanding global seawater circulation patterns. Two key challenges in generating such a datasets are: 1) the low concentration of Nd in seawater (especially in surface waters) and 2) the large number of sample analyses required. Data are reported for measurements from Nd sample amounts ranging 1 – 10 ng. Throughput of over 10 samples per hour was achieved. The external precision achieved for 143Nd/144Nd was better than 0.5 epsilon units (2s) for 2 ng samples amounts. 143Nd/144Nd.