1Lr3 is a more potent version of IGF-1Lr3. It's chemically altered i like to think "enhanced" to prevent deactivation by IGF-1Lr3 binding proteins in the bloodstream. This results in a longer half-life of 20-30 hours instead of 20 min... So that means a far more effective version...
The scientists obtained good linearity with serial dilutions (R2= 0.999, SEE = 0.135) and found 94% to 110% recovery when compared with expected results. In addition, samples spiked with recombinant human IGF1 gave 88–121% recoveries. Intra- and inter-assay coefficients of variation...