For nitrite ion, 1.)dil. H2SO4/HCl test - NO2 evolved
2.) White ppt. (AgNO2) with AgNO3 solution
3.) Turns acidified KI starch paper blue.
And about brown ring test, I'm not sure but it should give imo as it requires NO, which is evolved with acid, so unless with conc.H2SO4 it does not give NO, it should give brown ring test too.