Behavioral Variability in ABA Chemical Pretreatment Close to the 14C Age Limit

摘要: The acid-base-acid (ABA) procedure is a common chemical pretreatment used on most organic matter samples. Although this straightforward, there no consensus among labs about the optimum strength of chemicals, or even temperature, to be for digestions. Comparisons between 14C results obtained by samples undergoing ABA against other wet oxidations, such as acid-base oxidation followed stepped-combustion (ABOX-SC) α-cellulose wood, have sometimes suggested that does not always remove all contaminating carbon. In addition, if protocols are same, could it said one better than others comparable wet-oxidation pretreatments, rigorously applied? To determine whether 14C-free showed any fraction modern carbon (FmC) deviations due strategies, 3 experiments were carried out. first compared wood at near limit dating, pretreated with standard protocol UC Irvine’s Keck Carbon Cycle Accelerator Mass Spectrometry (KCCAMS) facility, those from ABA- and ABOX-SC-prepared aliquots same performed Australian National University (ANU) in 2001. second experiment subjected samples, ranging ~12 ka BP 14C-free, 5 selected published pretreatments. Third, we evaluated needs higher-strength final acid step (particularly important removing CO2 absorption when submerged alkaline solutions). We able show rigorous treatments exist can provide robust, reproducible many known >>50 BP, implying lack control over procedure’s outcome might sample-related, rather simply inadequacies pretreatment. DOI:  10.2458/azu_js_rc.55.16102