两种方法测定河虾、明虾和沼虾中的镉含量对比

Comparison of two methods for determination of cadmium content in shrimp,prawns and macrobrachium rosenbergii

目的建立石墨炉原子吸收光谱法和电感耦合等离子体质谱法测定虾中镉的方法并进行比较。方法样品经微波消解后，采用原子吸收光谱法和电感耦合等离子质谱法分别对河虾、明虾、沼虾的头和肌肉中镉含量进行测定，并比较两种方法的精密度和准确度。结果沼虾虾头中的镉含量高于国家标准数倍，其它虾肌肉中镉含量低于国标；两种方法测定虾中镉时，对于低含量镉，两者结果相差不大；但对于高含量时两者相差较大。原子吸收光谱法和电感耦合等离子质谱法测定同一浓度镉的精密度分别为：10．8％、2．2％，加标回收率分别为：93．5％～121．6％、99．5％～103．7％。结论原子吸收分光光度计测定镉时线性范围窄，测定高含量镉时要稀释多倍，造成结果不准确。质谱法具有抗干扰、线性范围宽、准确性好等优点，是测定虾中镉的最佳方法。

Objective To compare graphite furnace atomic absorption spectrophotometry （GFAAS） and inductively coupled plasma mass spectrometry（ ICP - MS） in determination of cadmium in shrimp. Methods After microwave digestion, the cad- mium contents in the head and muscle of shrimp, prawns and macrobrachium rosenbergii were determined by GFAAS and ICP - MS respectively, and the precision and accuracy of the two methods were compared. Results The content of cadmium in head of macrobrachium rosenhergii was several times higher than national standard limit, while that in muscles of shrimp and prawns was below the national standard. The two methods had little difference in determination of low - level cadmium, but greatly dif- ferent in determination of high - level cadmium. When the same concentrations of cadmium were determined by GFAAS and ICP - MS, the precisions were 10.8% and 2.2% respectively, and the recoveries were 93.5% - 121.6% and 99.5% - 103.7%. Conclusion Due to narrow linear range of GFAAS in detection of cadmium, the samples have to be diluted many times when determining high content of cadmium, which will cause inaccurate results. ICP - MS has the advantages of anti - interference, wide linear range, good accuracy, so it is the best method for determination of cadmium in shrimp.