FTIR spectroscopy and chemometrics for monitoring fibrinogen-containing preparations during purification

Batch-to-batch variability in fibrinogen-containing plasma fractionation by-products complicates standardization, necessitating rapid process-monitoring tools. This proof-of-concept study explored Fourier transform infrared (FTIR) spectroscopy combined with principal component analysis (PCA) to monitor a fibrinogen-containing preparation during processing. We analyzed raw precipitate, crude extract, and purified preparation from four independent production batches, alongside four commercial human fibrinogen lots, using FTIR spectroscopy and reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). PCA of spectra in the 1750-1107 cm⁻¹ region revealed four visually distinct clusters, with the first three principal components accounting for 99% of the total variance. Two additional final-product batches projected near the purified-preparation cluster. The purified preparation lacked a resolved feature at 1637-1639 cm⁻¹ and exhibited a dominant band at 1581-1582 cm⁻¹. SDS-PAGE demonstrated that the combined relative intensity of fibrinogen-associated Aα, Bβ, and γ bands increased from 64.6 ± 6.2% in raw precipitate to 82.5 ± 3.4% after purification, indicating fibrinogen enrichment rather than absolute purity. Due to differences in sampling configuration and matrix, spectral interpretation was limited to empirical fingerprints rather than direct measures of purity, aggregation, or secondary structure. These preliminary findings support further development of FTIR spectroscopy with PCA for process fingerprinting. However, routine implementation requires harmonized sampling, a larger number of independent production batches, predefined acceptance criteria, and external validation.