This document specifies a method for the quantitative determination of trans and total (cis + trans) vitamin K₁ in infant, pediatric and adult nutritionals using normal phase (NP) high-performance liquid chromatography (HPLC) with post-column reduction and fluorescence detection. The method demonstrated good linearity over a standard range of ~2 μg/l to 80 μg/l trans vitamin K₁, and the limit of quantification (LOQ) was estimated to be 0,4 μg/l for standards and 0,09 μg/100 g ready to feed (RTF) for samples assuming 4 grams of sample are diluted to 10 ml.