Which is the best ⁹Be carrier for ¹⁰Be/⁹Be accelerator mass spectrometry?

Commercial ⁹Be solutions used for chemical preparation of samples for accelerator mass spectrometry contain the cosmogenic long-lived radionuclide ¹⁰Be at elevated but different ¹⁰Be/⁹Be levels. Within a systematic study of recently produced solutions, comparison to published data and new data on customised solutions from minerals, we recommend - if no customised solution is available - the ⁹Be solutions from Australian Chemical Reagents (ACR) or from LGC. They contain ¹⁰Be/⁹Be at the 3.4 × 10^-15 level, which is still suitable for the majority of Earth science applications, compared to customised solutions at the 10^-16 level for lowest-level studies. Commercial solutions from Scharlab having different lot numbers, i.e. an identification number assigned to a particular lot of material from a single manufacturer, vary in ¹⁰Be/⁹Be by up to a factor of nine. Hence, it seems an advisable strategy to buy a bigger quantity of a single production batch (such as 10 × 100 ml bottles of ⁹Be at 1 g l^-1) and have them tested once at any AMS facility before first use.•The best ⁹Be carrier for low-level ¹⁰Be/⁹Be applications is a customised one from minerals like phenakite.•The best ⁹Be carriers for medium- and high-level ¹⁰Be/⁹Be applications are currently from Australian Chemical Reagents (ACR) or from LGC.•As ⁹Be carriers from Scharlab of different batches (LOT) contain ¹⁰Be/⁹Be at different levels, it is advisable to buy a bigger number of bottles of the same LOT of commercial carriers after being identified to have reasonably low isotope ratios.