This portable instrument measures total petroleum hydrocarbons in water and vapor in the field. It provides fast and accurate quantitative data for total petroleum hydrocarbons in water and vapor, and correlates with lab gas chromatographic analysis. The unit detects total petroleum hydrocarbons directly in water, vapor and floating liquid; provides in-situ, real-time information; logs data for up to 100 samples; and features automatic media sensing and easy-to-use menu-driven software.