Deuterated ethylenediaminetetraacetic acid edta d16

Three commercial Elmiron® batches (PPS 1 lot 14KG449 and PPS 2 lot 14JG315, PPS 3 lot 14NG729) were purchased in the United States and were used in this study. Ammonium acetate, sodium azide, sodium nitrate, sodium dihydrogen phosphate monohydrate, sodium hydrogen phosphate dihydrate, trimethylsilyl-3-propionic acid (TSP), dibutylamine (DBA, ≥99.5%, LC-MS grade), glacial acetic acid (99.9% LC-MS grade), methanol (LC-MS grade), ammonium chloride, sodium nitrite (>95%), sodium tetraborate, hydrochloric acid (≥37%), trifluoroacetic acid (≥99.5%), sulfuric acid (95-97%) were purchased from Sigma Aldrich (Milan, Italy); calcium acetate (>97%) from BDH; sodium acetate and NaOH from Merck (Kenilworth, NJ, USA); Amberlite IR 120 H+,0.1 M NaOH and dimethylsulfoxide from Fluka Analytical (Milan, Italy); Amberlite IR45 from Carlo Erba (Milan, Italy) pyridine from Riedel-de Haën (Germany); phenol (>99.5%). Ethanol (96%) was purchased from Girelli Alcool (Milan, Italy); deuterated ethylenediaminetetraacetic acid (EDTA-d16) from Cambridge Isotope Laboratories (Tewksbury, MA, USA) and deuterium oxide (99.9%) from Euriso-top (Saint-Aubin, France). Deionized water (conductivity less than 0.1 μS) was prepared with an osmosis inverse system (Culligan, Milan, Italy). PolyCAL ™ Pullulan std-57k (Malvern Instruments LtD, Malvern, United Kingdom). When not specified, the reagents are ≥98%.