Novel chemical compounds of the general formula K.sup.+A.sup.-, in which K.sup.+is a 5- or 6-membered heterocyclic ring having 1-3 hetereo atoms, which can be independently N, S, or O; with the proviso that at least one of the hetereo atoms must be a quaternized nitrogen atom having a --R'CN substituent, wherein R' is alkyl (C.sub.1 to C.sub.12); the heterocyclic ring having up to 4 or 5 substituents independently chosen from the moieties: (i) H; (ii) halogen or (iii) alkyl (C.sub.1 to C.sub.12), which is unsubstituted or partially or fully substituted by further groups, preferably F, Cl, N(C.sub.nF.sub.(2n+1-x)H.sub.x).sub.2, O(C.sub.nF.sub.(2n+1-x)H.sub.x), SO.sub.2(C.sub.nF.sub.(2n+1-x)H.sub.x).sub.2 or C.sub.nF.sub.(2n+1-x)H.sub.x where 1