In my thesis I developed a DMSPE method for the successful extraction of four pharmaceutical pollutants from water matrix by testing different types of sorbents and optimising the extraction and desorption conditions. I started with an experiment where I tried different sorbents at different pH. The most effective sorbent was found to be C18 Supelco. In the next step, I added an anion exchange sorbent SAX to that sorbent to improve the recoveries. I worked in four different pH ranges and a weakly acidic pH 4.2 proved to be the most suitable medium. As part of my thesis work, I also wanted to check the effect of sorbent mass on extraction, while determining the most efficient mass ratio between C18 sorbent and anion exchange sorbent. Another aim of this optimisation method was to reduce the overall time of the analytical procedure, or rather to reduce the extraction, shaking and desorption time. The only step that could be reduced by 15 min was the shaking step. The next challenge was to choose the desorption solvent, and I tried different solvents and solvent mixtures in different ratios, the best results were achieved with acetonitrile with 1% methanoic acid.
In the final step of this work, I used real samples of seawater and river water to study the matrix effect on extraction. The extracts were analysed by HPLC-DAD. The final recoveries of the compounds ranged between 55% and 90% and the RSD were less than 6% for all analytes.
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