The invention of the average formula (I) (formula, m 1 , n 1 , m 2 , and n 2 represents a positive number of less independently 0 or 2, with the proviso, m 1 + n 1 = 2, m 2 + n 2 = 2, also, 0 & lt m 1 + m 2 & lt 4, 0 & lt n 1 + n 2 & lt a sodium salt represented by and 4) and a method of manufacturing the same, and the sodium salt represented by average formula (I), as providing a method for inhibiting the degradation of a sodium salt represented by the general formula coexist (IV), improved stability over time and a salt represented by the general formula (IV).sodium salt, sodium-containing bases, downplayed salt stability, suppression of sodium salt decomposition method, the method of suppressing the occurrence of impurities sodium salt본 발명은 평균 화학식 (I)(식 중, m1, n1, m2 및 n2는 독립적으로 0 또는 2 이하의 양수를 나타내고, 단, m1+n1=2, m2+n2=2, 또한, 0
