电感耦合等离子体质谱法测定痕量铁元素时碰撞反应池条件的探讨

摘要

电感耦合等离子体质谱法( ICP-MS)在测量痕量铁元素时会受到ArO+多原子离子的严重干扰,碰撞/反应池技术可以有效的去除该干扰。通过对碰撞/反应池工作参数进行探讨,以提高ICP-MS检测铁元素的能力。讨论了NH3、He、H2、N2 O以及He-H2和He-NH3混合气6种四极杆碰撞/反应池气体类型及流速、碰撞/反应池RPq值、碰撞/反应池偏置电压( CRO)及四极杆质量分析器偏置电压( QRO)对ArO+干扰去除效果的影响,获得了优化的碰撞/反应池参数。实验表明：0.3 mL/min NH3-1.3 mL/min He混合气条件下得到的铁元素检出限最低；在不同的气体条件下RPq优化值为0.5；CRO及QRO在碰撞模式下优化值分别为-17 V、-7 V,在反应模式及混合气模式下分别为-1 V、-11 V；在优化条件下铁元素的检出限为14 ng/L。%The determination of trace iron by inductively coupled plasma mass spectrometry ( ICP-MS) was seriously interfered by polyatomic ion ArO+. Such interference could be effectively eliminated by the collision/reaction cell technology. In this paper, the working parameters of collision/reaction cell were investigated to improve the detec-tion ablity of iron by ICP-MS. The effect of several experimental factors on the elimination of ArO+interference was discussed, including six types of quadrupole collision/reaction cell gases ( NH3 , He, H2 , N2 O, He-H2 and He-NH3), the flow rate of gas, the collision/reaction cell RPq value, the collision/reaction cell offset (CRO) and quadrupole mass analyzer rod offset ( QRO) . The optimal parameters of collision/reaction cell were obtained. The experimental results indicated that the detection limit of iron was lowest when 0. 3 mL/min NH3-1. 3 mL/min He mixed gas was selected as the collision/reaction cell gas. The optimized RPq value was 0. 5 under different gas con-ditions. The optimized value of CRO and QRO under collision mode were -17 V and -7 V, respectively, and they were-1 V and-11 V respectively both under reaction mode and mixed gas mode. The detection limit of iron under optimized conditions was 14 ng/L.