1,4-Butanediol, 1ml

7-Hydroxy Methotrexate-d3 Ammonium Salt, 1mg

Sodium 1H,1H,2H,2H-perfluoro(1,2-13C2)dodecanesulfonate (10:2), 50µg/ml in MeOH, 1,2ml

EPA Method 537 Surrogate Primary Dilution Standard, in MeOH, 1,2ml