In this article, we present stochastic electrochemical analyses for the semi-quantitative determination of ion transfers (ITs) at an interface between water and electrochemically generated quaternary ammonium polybromide (QBr(2n+1)) droplets (water vertical bar QBr(2n+1)) in QBr aqueous solutions containing different acids (HAs). The concentration of Br- in QBr(2n+1), CBr-(QBr2n+1) is linearly proportional to CA-(aq) with the proportionality constant, which was estimated from the difference between the two partition coefficients of H+ and A(-) from water toward QBr(2n+1), KH+ - KA-, and the ratio of the mean activity coefficient of the aqueous over that of the QBr(2n+1) phase, gamma(+/-,aq)/gamma(+/-),(QBr2n+1). CBr-(QBr2n+1) also shows the linear function of CQ+(aq) with (gamma(+/-,aq)/gamma(+/-,QBr2n+1))KQ+ as its proportionality constant. The stochastic chronoamperometric analyses of QBr(2n+1) droplets during their particle-impacts on Pt UME in acidic solutions containing either N-methyl-N-ethyl pyrrolidinium bromide (MEPBr) or ethyl-pyridinium bromide (EPyBr) as model QBrs can provide indirect information about CBr-(QBr2n+1), and we estimated the relative order to be KC+(Li+ or Na+), KH+, and KA- : KC+(Li+ or Na+) < KH+ < KA-, where KHSO4- < KClO4- < KCl- in KA- and KNa+ < KLi+ in KC+. Also, we found that Br--IT at water vertical bar QBr(2n+1) is effectively limited by A(-)-IT in the acidic solutions, and Cl- is most significantly transferred to QBr(2n+1), leading to the complete inhibition of Br--IT into QBr(2n+1). (C) 2018 Elsevier Ltd. All rights reserved.