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Table 1 Summary of tests

From: Extended Stability of Reconstituted and Diluted SB3 (Trastuzumab Biosimilar) Assessed by Physicochemical and Biological Properties

Test Method Objective
Appearance (color) Visual inspection using yellow standard (Y1–Y7) Evaluation of color
Appearance (clarity) Visual inspection using turbidity standard (3 NTU–30 NTU) Evaluation of clarity level
Appearance (visible particulates) Visual inspection Determination of visible particle number
pH pH measurement Evaluation of pH
Protein concentration A280 measurement by UV–Vis spectrophotometer Determination of protein concentration
SE-HPLC UV detection (wavelength, 280 nm) Determination of the percentage of high molecular weight impurities
CE-SDS (non-reducing) UV radiation (wavelength, 220 nm) Determination of total purity and the presence of low molecular weight impurities
icIEF Capillary imaging at 4 °C Determination of the change in charge variance including acidic, main, and basic variants
Competitive inhibition binding assay to HER2 Fluorescence resonance energy transfer Determination of the relative binding to the reference standard
Anti-proliferation assay CellTiter-Blue® Cell Viability Assay Determination of the relative potency to the reference standard
Subvisible particulates Light obscuration Determination of particulate matter in subvisible particles (quantification of particles ≥ 10 μm, and ≥ 25 μm in size)
Subvisible particulates Microflow Imaging Determination of particulate matter in subvisible particles (quantification of particles ≥ 2 μm, ≥ 5 μm, ≥ 10 μm, and ≥ 25 μm in size)
Submicronic aggregation Dynamic light scattering Evaluation of the comparability of submicron particle size (1–1000 nm): hydrodynamic diameter and polydispersity index
  1. CE-SDS capillary electrophoresis–sodium dodecyl sulfate, HER2 human epidermal growth factor receptor 2, icIEF imaged capillary isoelectric focusing, NTU nephelometric turbidity units, SE-HPLC size exclusion high-performance liquid chromatography, UV ultraviolet, UVVis ultraviolet visible