Determination of Activated PEG Content on Substrate by 1H NMR Assay

Nitrosamine Impurities in Medicine:
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By A.B. Ferruzzi, Analytical Scientist, Impact Analytical
and J.P. Heeschen

The reliable, absolute quantitation of moisture-sensitive materials for activated polyethylene glycol (PEG) content can prove challenging for standard separation techniques, owing to analyte molecular weight. Herein we present a method based on liquid proton (‘H) nuclear magnetic resonance (NMR) spectroscopy for determining the weight per area loading of succinimidyl succinate polyethylene glycol (SS-PEG) on a substrate. Our method centers on preventing direct exposure of the sample material, internal standard, and solvent to the atmosphere during the SS-PEG extraction process and test solution preparation. With this method we obtained a 93.8% recovery for a 15000 Dalton SS-PEG.