Quantitative analysis of vitamin K1 in fruits and vegetables by isotope dilution LC-MS/MS

Abstract

A method has been developed for quantitative analysis of vitamin K₁ in vegetables and fruits by LC-MS/MS. The method employed a neutral aluminum oxide column for sample clean-up. Considering matrix effects, an isotope standard (vitamin K₁-D₇) was added to correct matrix interferences, as well as pretreatment losses and instrument variability. Spiked recoveries in model matrices were 88.3–90.1% for spinach, 84–110% for lotus roots, and 108–115.6% for grapes. The relative standard deviations (RSDs) were 1.0–7.1% for intra-day and 2.8–8.8% for inter-day. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001 mg kg⁻¹ and 0.004 mg kg⁻¹, respectively. The method is sensitive and reliable, which is successfully applied to different vegetable and fruit matrices. Vitamin K₁ in fruit samples ranged from 0.008 mg kg⁻¹ to 0.401 mg kg⁻¹, and in vegetable samples from 0.0032 mg kg⁻¹ to 3.973 mg kg⁻¹.