Analysis of residual crosslinking agent content in UV cross-linked poly(ethylene oxide) hydrogels for dermatological application by gas chromatography

Acrylates have been widely used in the synthesis of pharmaceutical polymers. The quantitation of residual acrylate monomers is vital as they are strong irritants and allergens, but after polymerization, are relatively inert, causing no irritation and allergies. Poly(ethylene oxide) (PEO) hydrogels were prepared using pentaerythritol tetra-acrylate (PETRA) as UV crosslinking agent. A simple, accurate, and robust quantitation method was developed based on gas chromatographic techniques (GC), which is suitable for routine analysis of residual PETRA monomers in these hydrogels. Unreacted PETRA was initially identified using gas chromatography-mass spectrometry (GC-MS). The quantitation of analyte was performed and validated using gas chromatography equipped with a flame ionization detector (GC-FID). A linear relationship was obtained over the range of 0.0002%-0.0450% (m/m) with a correlation coefficient (r2) greater than 0.99. The recovery (>90%), intra-day precision (%RSD <0.67), inter-day precision (%RSD <2.5%), and robustness (%RSD <1.62%) of the method were within the acceptable values. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.0001% (m/m) and 0.0002% (m/m), respectively. This assay provides a simple and quick way of screening for residual acrylate monomer in hydrogels.