5-(4H-1,2,4-Triazol-4-yl)-1H-pyrazole-4-carboxamide; Allopurinol Impurity C; Allopurinol Impurity 3; Allopurinol EP Impurity C; Allopurinol impurity C [EP]; Allopurinol impurity C CRS; Allopurinol Impurity 3(Allopurinol EP Impurity C)(Allopurinol USP Related Compound C ); Allopurinol Related Compound C; Allopurinol EP Imp C