黑芝麻、黑米中痕量镉的测定

摘要

A new flame atomic absorption spectrometry of cloud point extraction( CPE-FAAS)was es-tablished,in which 1-(2-pyridineazo)-2-naphthol( PAN)as the complexing agent and polyethylene glycol octyl phenyl ether nonionic surfactant( Triton X - 100 )as the extraction agent to determine the trace cadmium in black rice and black sesame. Some influence factor such as the types of complexing a-gent,the dosage of complexing agent,buffer solution and surfactant,pH,the equilibrium temperature,e-quilibrium time,centrifugal,ice bath time and interfering ions on the extraction rate were explored. Mo-reover,the feature indexes,detection limit,linear range for the test were also determined to investigate the precision and accuracy. Finally,the enrichment of cadmium in two black foods was determined at the optimized experimental conditions. It was shown that the method of enrichment ratio was up to nine times, the linear range of 0~1 200 μg·L-1 ,correlation coefficient R2 =0. 9995,and the detection limit was 0. 27 μg·L-1(n =11). Furthermore,the RSD were 1. 83% ~2. 24% and recoveries were between 93. 31% ~96. 28%,which indicated a high accuracy. It revealed that the method is simple,rapid,and efficient to detect the trace cadmium in black rice and black sesame.%以1-（2-吡啶偶氮）-2-萘酚（PAN）为络合剂，TritonX-100为萃取剂的浊点萃取-火焰原子吸收光谱法测定黑米与黑芝麻中痕量镉。探讨了不同络合剂、络合剂的用量、pH值、缓冲液用量、表面活性剂的用量、平衡温度、平衡时间、离心时间、冰浴时间、干扰离子等因素对萃取率的影响。结果表明：在优化实验条件下，对两种黑色食品中的镉进行富集和测定，该方法富集倍数为9倍，线性范围为0～1200μg·L-1，相关系数R2=0.9995，RSD在1.8%～2.2%之间，检出限为0.27μg·L-1（n=11）；加标回收率在93.3%～96.3%之间。方法简单、安全、快捷、灵敏、高效，适于黑芝麻、黑米等黑色食品中痕量镉的含量测定。