Influencing factors and uncertainty assessment for the simultaneous separation of organically bound tritium and 14C from marine products using a six-tube combustion device
Objective To develop a method for simultaneously processing and determining organically bound tritium(OBT)and 14 C in marine products and to analyze and evaluate the causes of the uncertainty in the determination process,aiming to achieve the rapid and accurate determination of OBT and14C in marine products such as sea fish,shrimp,crab,seashells and seaweed.Methods A six-tube combustion device equipped with a self-made six-way glass tube was utilized to develop a method for simultaneous complete combustion and collection of OBT and 14C in marine products.The uncertainty introduced in the processes such as elemental analysis,complete combustion,and liquid scintillation counting(LSC)was analyzed and evaluated.Results A simultaneous separation method,collecting OBT using five tubes and 14C using a single tube,was developed.Using this method,the combustion-based hydrogen(H)recovery was improved effectively using a-110℃ cold trap,the loss of samples during transfer decreased,and the quantity of reagents,such as sodium hydroxide,ammonium chloride,and calcium chloride,required for carbon collection greatly decreased.The H and C,including all of their isotopes,were simultaneously separated from 5.0 g of samples using the method,yielding combustion-based H and C recovery of 98.7％and 93.1％,respectively for glucose and ranging from 92.5％to 97.3％and from 82.7％to 96.3％,respectively for five types of marine products.Three parallel experiments produced relative standard deviations(RSDs)of all less than 5％,indicating the high accuracy and precision of the method.The uncertainty primarily originated from sample counting,followed by the element content analysis and counting efficiency.Conclusions The method for the simultaneous separation of OBT and 14 C from marine products developed in this study exhibits high combustion-based recovery,short processing time,ideal separation effects,and sufficient yield,thus effectively reducing the consumption of samples and meeting the requirements for the assessment of health risks caused by the radioactive contamination of marine products.
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