DEVELOPMENT OF ANALYTICAL METHODS FOR THE DETERMINATION OF SYNTHETIC MUD BASE FLUIDS IN MARINE-SEDIMENTS

A method for the extraction and quantification of synthetic drilling f luids in sediment, which could be adapted for different concentrations and types of synthetic fluid, was developed, Six different base fluid s mere investigated at four different concentrations (less than or equ al to 5, 100, 500 and 5000 mu g g(-1)). The method used varied dependi ng on the type and concentration of fluid in the sediment, Extraction of the base fluids was achieved by sonication in dichloromethane and m ethanol, The extract was purified using normal-phase high-performance liquid chromatography. Quantitative analysis was carried out by gas ch romatography with flame ionisation detection, Recoveries and limits of detection were calculated for each of the six synthetic fluids at eac h of the four concentration levels by spiking clean sediment, This met hod was used to monitor synthetic fluid concentrations in samples from sea-bed surveys and from a solid-phase test designed to assess the bi odegradabilitg of these compounds.