体积排阻高效液相色谱—电感耦合等离子体质谱法测定紫菜中镉(Cd)的形态

摘要

运用体积排阻高效液相色谱—电感耦合等离子体质谱联用技术( SEC-HPLC-ICP-MS)分析了紫菜中Cd的存在形态,结果发现,在紫菜水提取液中检测到3种Cd形态,根据其保留时间确定为植物螯合肽( PC)3-Cd、谷胱甘肽(GSH)-Cd和1种未知小分子有机态Cd,结合体外全仿生消化技术,研究了在唾液、胃、肠无机物和有机物(含消化酶)作用下,紫菜中Cd的主要存在形态,分析发现在紫菜胃全仿生提取液中,检测到2种未知小分子有机态Cd,其中以保留时间为24.2 min的Cd形态为主要存在形态.在肠全仿生提取液中检测到2种Cd形态,其中(PC)3-Cd是主要存在形态.有关(PC) 3-Cd在生物体内的代谢规律还需进一步研究.实验确证了Cd在紫菜中的主要有机形态,为紫菜食用安全风险评价提供重要依据.%High content of cadmium in laver has seriously affected the edible safety, export and industry development of seaweed in our country. However, only total cadmium content was detected by present method used worldwide and the total cadmium was used to evaluate the food safety of the laver which may over-estimate the toxicity of the cadmium in laver. Because there are different cadmium forms in laver which have different biological toxicities,the speciation analysis of cadmium in the laver is very urgent. However, studies on the cadmium speciation analysis in seaweed are very scarce at present. In present experiment, we first analyzed the different cadmium forms in laver (Porphyra haitanensis and Porphyra yezoensis) which have high Cd accumulation capability by using size exclusion chromatography-high performance liquid chromatography-inductively coupled plasma mass spectrometry ( SEC-HPLC-ICP-MS). The result showed that three Cd species including Phytochelatins(PC)3-Cd,glutathione(GSH)-Cd and one small molecule Cd species were detected in the deionized water extraction of the laver. In vitro whole-bionic digestion model was used to determine the main cadmium forms in laver under the action of saliva, the acidity of stomach and intestine with inorganic and organic components and digestion enzymes. Two unknown Cd species with small molecule were detected in whole-bionic digestion of gastric extracts, and the retention time of main species was 24. 2min. Two Cd species was detected in whole-bionic digestion of intestine extracts, and the main species was(PC)3-Cd. However,further study is needed to study the metabolic characteristic of(PC)3-Cd in the biology. Present study further proved the main organic cadmium species in seaweed and this has provided important basis for food safety evaluation of the laver.