I am performing adsorption studies in soil and desire to measure concentration metaleslibres in solution by voltammetry cyclic or voltammetry square wave, I'm working with high concentrations up to 2000 ppm, but not if I can measure this level concentrations using these techniques because the only publications I found where measured umol or ppb.
Thank you
have youtried stripping voltammetry ? i think it is Cyclic voltammetry - try anodic stipping voltammetry
see my lecture as ppt
dear student
i think anodic stripping voltammetry will do
pl see my lecture
In this case you need to determine parameters: DL (detection limit), SD (standard deviation)
Your questions is not completely clear: do you want enhance the detection limit or do you want to extend the uplimit concentration (or the linear response range)? If it is the former, you need to carry out in a two-step procedure normaly: 1) pre-concentration (say deposition), and 2) an anodic stripping. Compared to CV or SWV, differential pulse voltammetry (DPV) is more sensitive. In addition, Zn is too active to be detected by electrochemistry, for which you may need special electrode materials.
Teacher Qijin Chi, I need to extend the range of linear response, I need to construct a curve with concentrations between 10 ppm and 1000 ppm, is this possible with CV, SWV or DPV?
Those concentrations are very high so I would not use a stripping technique but simply a scanning method, without a deposition step. Probably best scan from -1.2 V to around 0 V and you get peaks for those 4 metals. You could use cyclic voltammetry for this, but I dont see the point of that. Just do a single scan and hold the potential at the positive end just prior to the scan to get rid of any deposited metal.
Alternatively you could scan in a negative direction starting from 0 V going to -1.2 V. That should work too.
There will be a background current from dissolved oxygen with two peaks: at -0.1 and -0.8 V or so. This may interfere if the concentrations are a bit low. You have to try it. You can remove the oxygen by purging with nitrogen, but I expect that you dont need to do this.
Then you have to choose an electrode. Mercury electrodes work well but you have then a waste problem. You could use a gold or carbon electrode too, or even a pencil.
wish you luck. Stan
Teacher Constant, thank you for your help, your answer was very useful to me
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