INTRODUCTION: Mineral oil hydrocarbons are typically found in water, foods and soils. These hydrocarbons can be extracted using a variety of solvents, with the most popular being hexane and petroleum ether. As concentrations can be very low, sample enrichment is often required. However, SCION instruments developed a method that simply uses a Large Volume Injection (LVI) technique to simplify sample pre-treatment whilst dramatically increasing throughput. The Hydrocarbon Index (HOI) is the total amount of compounds which can be extracted from water samples using a non-polar solvent. The solvent must have a boiling point between 39℃ and 69℃, thus replacing the use of halogenated solvents. Halogenated solvents and high concentrations of polar substances can interfere with the determination of the HOI. In addition, the compounds must not absorb on Florisil and must elute between ndecane and n-tetracontane. The method is suitable for HOI determinations in concentrations above 0.1mg/L in water samples.
This application note describes the highly efficient analysis of mineral oil hydrocarbons in water using the SCION 456 GC equipped with a Programmable Temperature Vaporiser (PTV). The system is very well suited to the DIN-EN-ISO 9377 method.