Sealed Tube Combustion Method with MnO₂ for AMS ¹⁴C Measurement

Abstract

ABSTRACT An effective sealed tube combustion method was designed with an MnO 2 oxidant for accelerator mass spectrometry radiocarbon (AMS 14 C) measurements. Different types of materials (oxalic acid, cellulose, sucrose, wood, collagen, graphite, and humic acid) were used to test the method. A normal borosilicate glass tube was used instead of quartz and the combustion was done at 550ºC. The yield of the combustion is above 98% even in the case of the less combustible material such as graphite. The MnO 2 reagent does not introduce detectable carbon contamination. The typical background is 0.29±0.20 pMC in the case of 200 µg carbon, measured as solid graphite target. With direct measurement of the CO 2 by gas ion source AMS, the method is applicable up to 50 µg of carbon with an acceptable (~1 pMC) 14 C background. A new type of tube cracker was developed for a quick chipless method of tube cracking and sample changing. In this way, the gas handling process takes only 5–6 min/sample.