食品放射性监测的快速微波灰化预处理方法研究

目的 建立一种快速、高效、清洁的食品放射性监测预处理方法。方法 采集秦山核电站周围包心菜、鲫鱼、海虾、牛奶、猪肉各10份，每份20 kg （牛奶20 L）。每种食品分成两组（传统方法组和微波方法组），每组5份，分别采用传统灰化法（干燥——炭化——马弗炉）和微波灰化法（微波灰化炉）分别进行灰化预处理，灰样采用HDEHP萃淋树脂分离β计数法测量放射性核素⁹⁰Sr，计算两种预处理方法的时间、灰鲜比及其对⁹⁰Sr分析流程的回收率，比较灰分形态、评价灰化效果。结果 传统方法组和微波方法组中包心菜的平均预处理时间分别为20和8.5 h，鲫鱼为54和26 h，海虾为46和23 h，牛奶为74和30 h，猪肉为58和26 h，微波方法组所用时间比传统方法组缩短一半及以上，动物性食品预处理时间明显缩短；微波方法组中食品灰鲜比高于传统方法组；微波方法组食品中⁹⁰Sr在分析流程中的回收率均在75%以上，高于传统方法组；微波灰化组中灰分呈灰白色，均匀，无炭黑残留，灰化完全。结论 微波灰化预处理法快速、高效、清洁、损失少、灰化效果好，可满足放射性食品快速预处理的要求。

Study on rapid microwave-ashing pretreatment method for radioactivity monitoring in food

Objective To establish a rapid, high-efficiency and clean way to monitor and pretreat the radioactivity in foods. Methods Food samples, 20 kg each of cabbage, crucian, shrimp, pork and 20 L of milk, were collected around Qinshan nuclear power plant, totaling 10 samples for each food. Each type of foods was arranged in two groups each with 10 samples. Samples were pretreated using traditional ashing method (TAM) and microwave ashing method (WAM) separately. HDEHP were used for ⁹⁰Sr separation and measurement. Calculations were made for the time spent on food pretreatment. The ash-fresh ratio and the recovery rate of ⁹⁰Sr by the two different method were calculated, with the quality of ash being evaluated. Results The mean time spent on pretreatment was cabbage 20 h, crucian 54 h, shrimp 46 h, pork 58 h and milk 74 h for TAM group, and cabbage 8.5 h, crucian 26 h, shrimp 23 h, pork 26 h and milk 30 h for WAM group, respectively. The time spent by WAM was half the time less than by TAM, especially for animal edible product. The ash-fresh ratios from WAM group were higher than from TAM group. The recovery rates of ⁹⁰Sr from WAM group in the analytical process were all above 75%, higher than from TAM group. Ashes produced by WAM were hoary, uniform, carbon residue-free and fully-ashed. Conclusions WAM pretreatment can pretreat food rapidly, efficiently, cleanly with less loss and better ashing effect. These can meet the requirement of rapid pretreatment of radioactivity in food.