The minimum detectable concentration of different forms of protein A are 40 pg/mL. The minimum detectable concentration was determined by adding twice standard deviations to the mean optical density value of twenty zero standard replicates and calculating the corresponding concentration.

The sample batch samples (6) were tested by ACRO and Competitor C’s Kits. The Protein A final concentration ratio between them is 0.6-3.4.

The same lot (53) samples were tested by those two kits. The acceptable recovery rate of ACRO (RES-A029) was 85%, and competitor C was 21%.

For Bevacizumab and Toripalimab, at low spiked concentration of Protein A (0.01ppm) level, Acro is better than Competitor C; meanwhile at high spiked concentration of Protein A (0.05ppm) level, the recovery rate of both are acceptable. For IVIG, the recovery rate for competitor C is not acceptable at both low and high spiked concentration of Protein A. But the recovery rate performance of ACRO are good at both levels. The results indicated that ACRO (RES-A029) was well tolerated when detecting Protein A residue in 20mg/mL IVIG.

The same batch of sample (8) were tested by ACRO (RES-A929) and competitor P’s kit. The Protein A final concentration ratio between them is 1.1-10.9.

3 samples were purified by Protein G, and no Protein A residue since they were not purified by Protein A. The OD450 signal of 3 samples tested by ACRO(RES-A029) was below the blank+2SD. It means there is no Protein A residue in those samples. But the OD450 signal of the same samples tested by Competitor P was far beyond the blank+2SD. It means there are non-specific binding of Competitor P kit.

For Bevacizumab，the recovery rate for both kits are acceptable at low and high spiked Protein A level.
For Toripalimab, at low spiked concentration of Protein A (0.01ppm) level, Acro is better than Competitor P; meanwhile at high spiked concentration of Protein A (0.05ppm) level, the recovery rate of both are acceptable.
For IVIG, the recovery rate for competitor P is not acceptable at both low and high spiked concentration of Protein A. But the recovery rate performance of ACRO are good at both levels. The results indicated that ACRO (RES-A029) was well tolerated when detecting Protein A residue in 20mg/mL IVIG.