中子活化法表征酸奶与苹果中有机卤化物

利用仪器中子活化分析、气相色谱和化学分离相结合的方法,研究随机采自北京、深圳超市的酸奶(20个品牌)和苹果(9种)中总卤素、可萃取有机卤素、可萃取持久性有机卤素和可鉴别持久性有机氯.结果显示,Cl、Br和I的INAA探测极限分别为50 ng、8 ng和3.5 ng.酸奶中可萃取有机氯占总氯含量的0.005%～0.043%,其中约24%为耐浓硫酸的可萃取持久性有机氯,可鉴别有机氯占总EPOCl的0.7%～13.1%;苹果中相应比例分别为1.6%～5.1%、34%和0.5%～6.2%,表明酸奶与苹果中的氯化物主要为极性水溶性化合物,EOCl主要为酸溶或酸不稳定氯化物,大部分EPOCl为现代气相色谱技术尚不能鉴别的未知化合物,仍留待人们去认识.

Study of organohalogens in yogurt and apple by neutron activation analysis and related techniques

Twenty brands of Chinese commercial yogurt specimens and nine different kinds of apple samples collected randomly from supermarkets in Beijing and Shenzhen,China,were analyzed by instrumental neutron activation analysis (INAA) combined with gas chromatography (GC) and chemical separation methods for total halogens,extractable organohalogens (EOX),extractable persistent organohalogens (EPOX) and identified organochlorines. The INAA detection limits are 50 ng,8 ng and 3.5 ng for Cl,Br and I,respectively. The extractable organochlorines (EOCl) accounted for 0.005% to 0.043% of the total chlorine in yogurt and 1.6% to 5.1% in apple.About 24% of EOCl kept undecomposed as the extractable persistent organochlorines (EPOCl) after treatment with concentrated sulfuric acid in yogurt,and 34% in apple.These results indicated that chlorine in the two selected foodstuffs mainly existed as inorganic species and non-extractable organochlorines,and most EOCl in yogurt and apple were acid-liable or acid-soluble fractions. The Ratios of identified organochlorines to total EPOCl were 0.7% to 13.1% and 0.5% to 6.2% in yogurt and apple samples,respectively,which implying that a major portion of EPOCl measured in yogurt and apple remained uncharacterized.