The microFAST MC combines the advantages of the SC-µDX autosampler with single or dual loop FAST capabilities and syringe based sample loading/injection. The system accurately loads a loop and then smoothly injects the solution into a μFlow concentric nebulizer at defined rates from 5-1000 μL/min. The valve on the flow injection system selects from two discrete, parallel flow paths. This allows rapid switching between solutions with minimal dead volume between the valve and the nebulizer.
Li isotope ratios are measured using the microFAST MC system. Syringe injecting 100 μL of sample at 20 μL /min provides nearly 5 minutes of steady state signal for isotope ratio analysis. External reproducibility is improved for the smallest absolute sample amounts (6ng) using low volume solution aliquots.
Minimizing the amount of Nd required to obtain desired precision (> 50 ppm) and throughput for precious oceanographic samples is illustrated in two figures. First, internal precision is for plotted for variable amounts of Nd injected at 100 µL/min for two minutes. Less than 50 ppm (2 RSD) internal precision is obtained for 2 ng samples of Nd. Repeat analysis of reference materials JNdi and La Jolla indicate that the external precision for 2 ng of Nd is similar to the 50 ppm internal precision and appropriate for oceanographic applications.
The microFAST MC is used to load small volume samples, provide stable injection profiles and rapid washout for precise Pu isotope ratios.
The microFAST MC and the apex Ω provide high precision potassium isotope ratios with greatly reduced uptake and wash times, thereby improving frequency of sample standard bracketing.