The present disclosure provides a vacuum ultraviolet (VUV) detector for use with a liquid chromatography (LC) system (otherwise referred to herein as an LC-VUV detector) for the study of liquids. The LC-VUV detector incorporates an ultra-short pathlength flow cell into the LC-VUV detector to render liquid samples at least semi-transparent to VUV light. The ultra-short pathlength flow cell is specifically designed to: (a) interface with a focused beam of VUV light, (b) provide zero ‘dead’ volume, resulting in perfectly laminar flow through the flow cell, and (c) be modular and removable, allowing flow cells of different pathlength to be used within the LC-VUV detector. Methods for analyzing liquid samples using the LC-VUV detector and flow cell disclosed herein are also provided in the present disclosure.