A method of reducing the amount of a protonic acid salt of a tertiary amine in a quaternary ammonium salt, said method comprising: adding an oxide or hydroxide of a Group 1, 2, 12 or 13 metal to a quaternary ammonium salt containing said protonic acid salt of a tertiary amine as an impurity, wherein the anion of the quaternary ammonium salt is selected from the group consisting of CF 3 CO 2 -, CF 3 SO 3 -, BF 4 -, AlF 4 -, CIBF 3 -, (FSO 2) 2 N -, PF 6 -, AsF 6 -, ClO 4 -, N(CF 3 SO 3) 2 -, C(CF 3 SO 3) 3 -, RfSO 3 -, RfCO 2 -, wherein Rf is fluoroalkyl having 1 to 8 carbon atoms; (R r1 SO 2)(R r2 SO 2)N - and (R r1 SO 2)(R r2 CO 2) -, wherein R r1 and R r2 are the same or different and are each fluoroalkyl having 1 to 8 carbon atoms; and wherein the protonic acid is selected from the group consisting of CF 3 CO 2 H, CF 3 SO 3 H, HBF 4, HAIF 4, HCIBF 3, (FSO 2) 2 NH, HPF 6, HAsF 6, HClO 4, NH(CF 3 SO 3) 2, HC(CF 3 SO 2) 3, RfSO 3 H, RfCO 2 H, wherein Rf is fluoroalkyl having 1 to 8 carbon atoms; (R r1 SO 2)(R r2 SO 2)NH and (R r1 SO 2)(R r2 CO 2)H, wherein R r1 and R r2 are the same or different and are each fluoroalkyl having 1 to 8 carbon atoms, and thereby neutralizing the tertiary amine protonic acid salt with the metal oxide or hydroxide to convert the acid salt to a tertiary amine and water and to convert the metal oxide or hydroxide to a metal salt at the same time, and removing from the system the tertiary amine and water by distillation or heating while introducing nitrogen, argon or air, and metal salt produced by filtration or column purification. adding an oxide or hydroxide of a Group 1, 2, 12 or 13 metal to a quaternary ammonium salt containing said protonic acid salt of a tertiary amine as an impurity, wherein the anion of the quaternary ammonium salt is selected from the group consisting of CF 3 CO 2 -, CF 3 SO 3 -, BF 4 -, AlF 4 -, CIBF 3 -, (FSO 2) 2 N -, PF 6 -, AsF 6 -, ClO 4 -, N(CF 3 SO 3) 2 -, C(CF 3 SO 3) 3 -, RfSO 3 -, RfCO 2 -, wherein Rf is fluoroalkyl having 1 to 8 carbon atoms; (R r1 SO 2)(R r2 SO 2)N - and (R r1 SO 2)(R r2 CO 2) -, wherein R r1 and R r2 are the same or different and are each fluoroalkyl having 1 to 8 carbon atoms; and wherein the protonic acid is selected from the group consisting of CF 3 CO 2 H, CF 3 SO 3 H, HBF 4, HAIF 4, HCIBF 3, (FSO 2) 2 NH, HPF 6, HAsF 6, HClO 4, NH(CF 3 SO 3) 2, HC(CF 3 SO 2) 3, RfSO 3 H, RfCO 2 H, wherein Rf is fluoroalkyl having 1 to 8 carbon atoms; (R r1 SO 2)(R r2 SO 2)NH and (R r1 SO 2)(R r2 CO 2)H, wherein R r1 and R r2 are the same or different and are each fluoroalkyl having 1 to 8 carbon atoms, and thereby neutralizing the tertiary amine protonic acid salt with the metal oxide or hydroxide to convert the acid salt to a tertiary amine and water and to convert the metal oxide or hydroxide to a metal salt at the same time, and wherein the anion of the quaternary ammonium salt is selected from the group consisting of CF 3 CO 2 -, CF 3 SO 3 -, BF 4 -, AlF 4 -, CIBF 3 -, (FSO 2) 2 N -, PF 6 -, AsF 6 -, ClO 4 -, N(CF 3 SO 3) 2 -, C(CF 3 SO 3) 3 -, RfSO 3 -, RfCO 2 -, wherein Rf is fluoroalkyl having 1 to 8 carbon atoms; (R r1 SO 2)(R r2 SO 2)N - and (R r1 SO 2)(R r2 CO 2) -, wherein R r1 and R r2 are the same or different and are each fluoroalkyl having 1 to 8 carbon atoms; and wherein the protonic acid is selected from the group consisting of CF 3 CO 2 H, CF 3 SO 3 H, HBF 4, HAIF 4, HCIBF 3, (FSO 2) 2 NH, HPF 6, HAsF 6, HClO 4, NH(CF 3 SO 3) 2, HC(CF 3 SO 2) 3, RfSO 3 H, RfCO 2 H, wherein Rf is fluoroalkyl having 1 to 8 carbon atoms; (R r1 SO 2)(R r2 SO 2)NH and (R r1 SO 2)(R r2 CO 2)H, wherein R r1 and R r2 are the same or different and are each fluoroalkyl having 1 to 8 carbon atoms, and thereby neutralizing the tertiary amine protonic acid salt with the metal oxide or hydroxide to convert the acid salt to a tertiary amine and water and to convert the metal oxide or hydroxide to a metal salt at the same time, and removing from the system the tertiary amine and water by distillation or heating while introducing nitrogen, argon or air, and metal salt produced by filtration or column purification.