A xylylenediisocyanate composition including xylylenediisocyanate and a compound represented by Chemical Formula (1) below, wherein 0.6 ppm or more and 60 ppm or less of the compound represented by Chemical Formula (1) below is contained:

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A method forming a surface modifying composition with reduced need for organic solvent and evaporation thereof for removal of insoluble reaction byproducts from the composition. The purified composition can be used in the formation of articles having improved biocompatibility, such as medical articles (e.g., spun hollow fiber).