Synthesis of DiLeu labels required purchasing the following isotopic reagents from ISOTEC Inc (Miamisburg, OH): leucines (ʟ-leucine and ʟ-leucine-1-¹³C,¹⁵N), heavy formaldehyde (CD₂O, 20% w/w), sodium cyanoborodeuteride (NaBD₃CN), ¹⁸O water (H₂¹⁸O), and deuterium water (D₂O).
Source: wiktionary