I would try to avoid nitric since it is an oxidizing acid and might affect your results but in General YES if they suggested it (and did not try it) why not give it a shot ? maybe you will get better results? if not you tried and learned something. I would also look at who cited their work (since its from 1975) maybe they did something to improve the LOD ? 

As I said Cl- and Au will dissolve some of the electrode and 1M is very high. do you need such a low pH ? in their graph they plot the peak vs pH and ph 1-3 is almost the same so why not use 1mM HCl (pH 3 ) ? 

Well one thing that is causing you a lot of problems is your electrolyte. I dont know what is you potential window but I am pretty sure you are dissolving your electrode. 1M of HCl is a very high concentration of Cl- so you dissolving to Au(s) to gold chloride which is changing your active surface so even after activation in H2SO4 it wont be exactly identical. Do you have to work in such an acidic environment ?   Can you use a non chloride based acid ? if you have to, maybe polishing the electrode like suggested will help

Thanks Christian.  This is what exactly I have been doing but I do not sonicate it as frequently as I do CV with sulfuric acid.  So you mean this is the best possible way to make sure the electrode is clean and fit for subsequent runs? Well, if this is so, then what might be the reason for not getting consistent results? I use Pt wire as counter and Ag/AgCl for reference.

Hi Tomer,

To be precise, I am working on detection of arsenic and according to the article:

http://pubs.acs.org/doi/pdf/10.1021/ac60359a057

1M HCl shouldn't be a problem - they did suggest usage of perchloric/phosphoric/sulphuric/nitric acid too.  Do you mean replacing the supporting electrolyte with a non-chloride based acid would improve the results? Thank you for the reply :)

I would try to avoid nitric since it is an oxidizing acid and might affect your results but in General YES if they suggested it (and did not try it) why not give it a shot ? maybe you will get better results? if not you tried and learned something. I would also look at who cited their work (since its from 1975) maybe they did something to improve the LOD ? 

As I said Cl- and Au will dissolve some of the electrode and 1M is very high. do you need such a low pH ? in their graph they plot the peak vs pH and ph 1-3 is almost the same so why not use 1mM HCl (pH 3 ) ? 

I think Tomer is right. Using HClO4 would be much better than HCl. In the meantime, the potential window is also important. Pure Au is quite stable in HCl, but when AuOx formation the electrode surface will be changed. In fact, we have used this feature in our Group for many years to clean our single-crystal Au electrodes such as Au(111), Au(100) or Au(110). Electropolish would be a good way for your purpose as well. You migh take a look at our publications.  

Is important that you clean thoroughly the polishing pads. I think that 10 cycles in sulfuric acid is not enough. Stronger acids -and sometimes piranha solution- are good to clean the electrode surface. Test your electrode cleanliness procedure by CV of ferricianyde/ferrocianyde cuasi-reversible redox couple. The Delta Ep depends on electrode cleanliness.

Hi Qijin,

Many thanks for the papers :)  Right now I am using the potassium hydroxide and hydrogen peroxide method as well as potassium hydroxide potential sweep method as described in the attached paper for cleaning electrodes.

Hi Sebastian,

Thank you and I now am running 20-25 cycles :)

Hi Tomer,

I did work on your suggestion on reducing the concentration of supporting electrolyte.  I tried repeating the experiment by gradually reducing the concentration of HCl from 1M to 0.1M.  I could get distinct "peaks" for the stripping voltammetry experiments until 0.5M HCl as supporting electrolyte.  When I reduce the concentration beyond 0.5M, there is a significant drop in the "peak current" as as I tried it with 0.1M HCl, the S/N dropped and there is no "distinct" peak observed.  Hence I feel using 0.5M or 1M HCl is necessary.  Even other literature also have used higher concentrations of HCl.  For instance:

planetary.chem.tufts.edu/Talanta2002.pdf

mentions usage of 2M HCl for the detection of As.

I shall now also repeat the experimentation with HCl repleaced by HClO4 and let you know my observations.

Thanks and regards,

Sujeevan.

planetary.chem.tufts.edu/Talanta2002.pdf