You have to know that It's a big challenge to detect arsenic (III) in basic medium.

In carbonate buffer, you must add KCl or a good electrolytic conductor; you must apply a deposing potential less or equal to -1000 mV; and if it's possible in stirring conditions.

You can also try DPASV or SWASV that more sensitive than LSASV

In CV you must begin in going in the cathodic direction after deoxygenating the medium. 

Good luck

Thanks abdoul, I will take your suggestion and will add KCl before Arsenic detection.

I tried both SWASV and DPASV, but I am not getting results. What do you mean by going in cathodic direction in CV?

Also, I am working in stirring condition under nitrogen environment.]

I will let you know what i get after Kcl addition.

-Praveen

I have seen people reported arsenic in various buffers (PBS, acetate buffer and carbonate buffer) in ph range 5 to 10. But I am not able to detect in these buffers even at bare glassy electrode. Could anyone guide where I am mistaking ?

Why do not use the ICP MS to detect the arsenic species or concentrations in carbonate buffer??