Re-evaluation of the New Oxalic Acid standard with AMS

Abstract The New Oxalic Acid standard (NOX) was introduced in 1980 to replace the primarily Oxalic Acid (OX) standard, which was calibrated against OX utilizing decay counting measurements. However today, most radiocarbon measurements are performed with accelerator mass spectrometry that is more powerful as significantly less material is required and the measurement time is reduced. Here we give an update on the calibration of the NOX against OX. Over 500 radiocarbon measurements on either OX or NOX were compiled to an exact calibration, that outperforms the original calibration in precision. Our measurements are in agreement with the first measurements performed in the 80’s, demonstrating that AMS is capable of reproducing highest precision radiocarbon measurements on a routine basis.