富硒农产品硒含量检测方法的研究与探讨

Study and Discussion on the Determination Method of Selenium Content in Selenium Rich Agricultural Products

摘要: 中国是世界上缺硒最严重的国家之一，约7亿人处在硒营养不足状态。因此，研究和应用外源补硒技术，提高农产品尤其是主粮的硒含量，对非富硒地区而言显得尤为重要。农产品硒含量的测定是富硒技术研发的重要环节，目前我国以氢化物–原子荧光光谱法为首选检测方法(GB5009.93-2017)，本研究以富硒稻米为对象，分析和探讨了原子荧光光谱法中广泛应用的三种湿发消解方法(A、B、C)对稻米硒含量检测结果的影响。研究表明：1) 原子荧光光谱法采用不同湿法消解方法检测的稻米硒含量的变异系数(CV)，处理B的CV平均数最小，整体上说明该方法的稳定性较好。2) 以三种湿法消解方法的稻米硒含量总平均值0.926 mg/kg为参照，我们初步认为，以“硝酸 + 高氯酸酸系、80℃ (60 min)-升温至100℃ (60 min)-升温至130℃(60 min)消解升温流程、190℃赶酸温度”(处理C)，具有较高的准确性。3) 同一家检测机构对三种湿法消解方法的检测结果存在显著(P < 0.05，下同)或极显著差异(P < 0.01，下同)，说明不同的湿法消解方法对原子荧光光谱法的检测结果具有重要影响。4) 同一种湿法消解方法三家检测机构的检测结果均存在极显著差异，说明硒检测的准确性除了湿法消解方法影响因素外，还存在某些操作细节因素的影响，除了可能存在的检测设备差异外，更重要的是与操作的精准性有关，这一情况应引起检测行业的高度重视，建议在检测标准制(修)定中应进一步细化操作流程。

Abstract: China is one of the most serious selenium deficient countries in the world, and about 700 million people are in the state of selenium deficiency. Therefore, the research and application of exogenous selenium technology to improve the selenium content of agricultural products, especially the main grain, is particularly important for non-selenium rich areas. The determination of selenium content in agricultural products is an important link in the research and development of selenium rich technology. At present, hydride generation atomic fluorescence spectrometry (HG-AFS) is the preferred detection method in China (GB 5009.93-2017). In this study, the effects of three wet digestion methods (A, B, C) widely used in atomic fluorescence spectrometry (AFS) on the detection results of selenium content in rice were analyzed and discussed. The results showed that: 1) The coefficient of variation (CV) of rice selenium content detected by Atomic Fluorescence Spectrometry with different wet digestion methods was the smallest, indicating that the method was stable on the whole. 2) Taking the total average value of selenium content of rice by three wet digestion methods as reference, we preliminarily believe that the process of “nitric acid + perchloric acid system, 80˚C (60min)-heating to 100˚C (60 min)-heating to 130˚C (60 min), and 190˚C acid driving temperature” (treatment C) has high accuracy. 3) There were significant differences (P < 0.05, the same below) or very significant (P < 0.01, the same below) between the three wet digestion methods in the same testing institution, which indicated that different wet digestion methods had an important impact on the detection results of atomic fluorescence spectrometry. 4) For the same wet digestion method, there are significant differences in the test results of three testing institutions, which indicate that the accuracy of selenium detection is affected by some operation details besides the influencing factors of wet digestion method. In addition to the possible differences of detection equipment, the more important thing is the accuracy of operation. This situation should be highly valued by the testing industry. It is suggested that the operation process should be further refined in the preparation (Revision) of testing standards.