普通模式与八极杆碰撞/反应池电感耦合等离子体质谱法测定大米中痕量硒和铬的比较

Comparison of determination of trace selenium and chromium in rice by normal mode and eight-pole collision/reaction pool inductively coupled plasma mass spectrometry

目的建立八极杆碰撞/反应池(octopole reaction system,ORS)结合电感耦合等离子体质谱法测定大米中痕量铬和硒元素含量的方法,并比较普通模式和ORS模式对2种元素测定结果的差异。方法ORS模式采用屏蔽矩技术结合氦气碰撞反应池消除40Ar12C+对52Cr、39Ar39Ar+和40Ar38Ar+对78Se的干扰,选用丰度较高的同位素52Cr、78Se测定。普通模式通过在线加入内标校正基体干扰,选择同量异位素干扰较少的同位素53Cr、82Se测定。结果普通模式铬和硒元素的检出限为0.059、0.023μg/L,而ORS模式铬和硒的检出限为0.027、0.012μg/L。ORS模式下,铬、硒元素在0~100μg/L浓度范围内与检测信号线性关系良好,相关系数大于0.9998。结论普通模式用于测定铬和硒含量较高的大米样品是可行的,应用ORS模式在痕量样品分析时测定结果更准确可靠。

Objective To establish a method for the determination of trace selenium and chromium in rice by octopole reaction system(ORS)-inductively coupled plasma mass spectrometry, and compare the results and the difference between the normal mode and the ORS mode. Methods In ORS mode, shielding torch technology combined with helium collision reaction pool was adopted to eliminate the interference of 40Ar12C+ on 52Cr, 39Ar39Ar+ and 40Ar38Ar+ on 78 Se. Isotope 52 Cr and 78 Se with higher abundance were selected for determination. In the normal mode, the isotopes with less interference of isotopes(53 Cr and 82 Se) were selected for determination by adding internal standard online to correct the matrix interference. Results The detection limits of 53Cr and 82Se with no gas mode were 0.059 μg/L and 0.023 μg/L, while the detection limits of 52Cr and 78Se with ORS mode were 0.027 μg/L and 0.012 μg/L. In ORS mode,52Cr and 78Se had good linear relationship within the concentration range of 0-100 μg/L, and the correlation coefficient were greater than 0.9998. Conclusion It is feasible to determine rice samples with high content of chromium and selenium in the normal mode, and the determination results are more accurate and reliable in the trace sample analysis with ORS mode.