γ能谱无源效率模拟中食品样品成分分析研究

Analysis of food sample composition for gamma spectrometry-based sourceless efficiency simulation

目的通过分析常见食品的成分,利用无源效率刻度与有源验证相结合的方法,为食品γ能谱无源效率刻度分析推荐参考成分。方法对全国食品放射性污染监测中30种常见食品样品进行分析,统计出粮食类和蔬菜类的参考成分,结合白藜麦标准源的自身参数,应用LabSOCS进行白藜麦标准源不同成分的无源效率模拟,计算白藜麦标准源测量活度与其证书活度的相对偏差并进行分析。结果30种食品样品的检测结果表明,C、H、O、N、S这5种元素占食品组成的77.0%~93.7%,是食品的主要成分。将白藜麦自身成分和粮食类参考成分应用于白藜麦标准源的无源效率模拟,进行活度计算,与其证书活度的相对偏差绝对值分别在0.37%~5.86%和0.38%~5.87%。结论白藜麦自身成分和粮食类参考成分应用于白藜麦标准源的无源效率模拟,计算的测量活度与标准源证书活度的相对偏差基本一致,若使用γ能谱无源效率模拟测量未知成分的食品样品且不便进行食品样品成分分析时,特别是在应急情况下,可参考使用本研究得到的参考成分。

Objective To recommend reference composition for sourceless efficiency calibration of food gamma spectrometry by analyzing the composition of common foods based on a combination of sourceless efficiency calibration and active validation.Methods Thirty common types of food samples in countrywide monitoring of radioactively contaminated foods were analyzed to statistically determine the reference composition of grains and vegetables.Combined with the parameters provided for white quinoa standard source,LabSOCS was applied to carry out the simulation of sourceless efficiency for its different compositions,and to calculate its measured activity,and analyzing its relative deviation to the those given in the certificate.Results The analytical result of these 30 types of food samples showed that the five elements C,H,O,N and S accounted for 77.0%-93.7%of the food composition,being the main component of these samples.By applying white quinoa′s components and grain-based reference components to the simulation of the sourceless efficiency of white quinoa standard sources,the relative deviations of activity calculations to their certificated activities were in the range of 0.37%-5.86%and 0.38%-5.87%in absolute value,respectively.Conclusions The white quinoa′s composition and the grain reference composition were applied to the sourceless efficiency simulation of the white quinoa standard source,and the relative deviation of the calculated measured activity to the activity of the standard source certificate was basically identical,so that if the gamma spectrometry-based sourceless efficiency simulation is used to measure the unknown composition of the food samples and it is inconvenient to carry out the analysis of the food samples′compositions,especially in the case of emergency,it can be referred to the use of the reference compositions obtained in the present study.