Analysis of Ag, Sb, Sn (ICP-MS Agilent 7900)

Hi everyone. Im using the Agilent 7900 for the analysis of a bunch of analytes in water samples without any problems, except for Ag, Sb and Sn. Im having a problem with the calibration curves of these three analytes because the calibration curves are not linear, it almost seems theat I swaped the points of the calibration between each other. So of course I tried to clean every part, changed all tubings, I have new conuses, every reference material and solution are fresh. Im using macerated plastic bottles for storage of the solutions, adding HNO3 into every solution. Im using He mode, and I chose the following isotopes: Ag 107; Sn 118; Sb 121. The points of the calibration curves for the Ag and Sb are 1; 25; 50; 75; 100 ppb and for the Sn 10; 250; 500; 750; 1000 ppb. And I measure them together with the following analytes: Li, Be, B, V, Se, Sr, Mo, Ba.  So I was wondering, if anyone has a similar problem. Or someone has an idea what should I try. Thank you very much.

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  • Hi Rodolfo, the behaviour is very random. Mostly the higher points showing that behaviour. I am fighting with it for almost a year. Sometimes helps when I make fresh calibration, but in the next analysis its bad again, or sometimes the calibration curve is beautiful, but the CRM for the QC check is horrible. And I dont change anything in the method between the analyses. I use always the same type of bottles, I soak them overnight with 10% HNO3. And when I am making the calibration curve, I always use a high purity single component solution (1000 mg/l) for every single element. So I dont really know, where are we doing mistakes. Do these elements have some memory efect? Or are they that problematic elements, that they need some special care, maybe other settings in the method?   I print screened some calibration curves, the bad ones and the good one too.   Thank you.

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