Development of Analytical Methods for the Determination of Synthetic Mud Base Fluids in Marine Sediments†

Abstract

A method for the extraction and quantification of synthetic drilling fluids in sediment, which could be adapted for different concentrations and types of synthetic fluid, was developed. Six different base fluids were investigated at four different concentrations (≤5, 100, 500 and 5000 µg g^–1). The method used varied depending on the type and concentration of fluid in the sediment. Extraction of the base fluids was achieved by sonication in dichloromethane and methanol. The extract was purified using normal-phase high-performance liquid chromatography. Quantitative analysis was carried out by gas chromatography with flame ionisation detection. Recoveries and limits of detection were calculated for each of the six synthetic fluids at each of the four concentration levels by spiking clean sediment. This method was used to monitor synthetic fluid concentrations in samples from sea-bed surveys and from a solid-phase test designed to assess the biodegradability of these compounds.