摘要
由于受到锆的氢氧化物和钼的氧化物的质谱干扰,电感耦合等离子体质谱法很难直接准确测定土壤中的镉含量。采用电感耦合等离子体串联质谱法,选用^(111)Cd+作为分析同位素,在原位质量模式(MS/MS)下向通用池中通入氨气,使得m/z=111处锆的氢氧化物和钼的氧化物与氨气发生反应形成新的氨簇离子团导致质荷比发生改变,从而降低这些多原子离子对^(111)Cd+质量重叠的干扰。当氨气流量在1.1 mL/min时,含有10 mg/L锆和1 mg/L钼的混合溶液在m/z=111处的干扰降低至1.4 ng/L,相比标准模式干扰降低99.97%。在优化实验条件后,方法检出限为0.002mg/kg,测试土壤标准物质的相对误差为–8.2%~3.3%,测试3个实际样品的相对标准偏差在2.9%~8.8%之间。该方法检出限低,精密度和准确度较好,抗干扰能力强,可实现土壤中痕量镉元素的测定。
It is difficult to determine the content of cadmium in soil directly and accurately by inductively coupled plasma mass spectrometry due to the mass spectrum interference of zirconium hydroxide and molybdenum oxide.^(111)Cd+was selected as the optimal ion by ICP-MS/MS.Meanwhile,ammonia was introduced into the universal cell in the MS/MS mode,so that the zirconium hydroxide and molybdenum oxide at m/z=111 reacted with ammonia to form new ammonia ion clusters,which resulting in the change of mass charge ratio in order to reduce the interferences of these polyatomic ions on the mass overlap of cadmium.When the ammonia flow rate was 1.1 mL/min,the interferences of the mixture solution containing 10 mg/L zirconium and 1 mg/L molybdenum at m/z=111 were less than 1.4 ng/L,and the interferences were decreased 99.97%.With the optimal experimental condition,the detection limit of the method was 0.002 mg/kg,the relative error of soil reference materials was between-8.2%and 3.3%,and the relative standard deviation of three actual samples was between 2.9%and 8.8%.The method held the advantages of low detection limit,good precision and accuracy,strong anti-interference ability,which could fulfill the determination of trace cadmium in soil.
作者
刘跃
王记鲁
林冬
李静
王鑫
LIU Yue;WANG Jilu;LIN Dong;LI Jing;WANG Xin(Tianjin Eco-Environmental Monitoring Center,Tianjin 300191,China)
出处
《中国测试》
CAS
北大核心
2023年第10期90-96,共7页
China Measurement & Test
