The first part of this research is dedicated to the biodegradability of 5 pharmaceuticals: ampicillin, cephalexin, cefazolin, ceftazidime and acetaminophen. Closed bottle test (CBT) was used as a first, simple test for the assessment of the biodegradability of target compounds. The test solution of each drug with concentration of 3 (mg/l) was prepared with mineral medium and small amounts of microorganisms (0.5 mL inoculums / L mineral medium) of a population of microbial. The mineral solutions are prepared from stock solutions of appropriate concentrations of mineral components, namely, potassium and sodium phosphates plus ammonium chloride, calcium chloride, magnesium sulphate and iron chloride. The blank, standard, control and suspension solutions were used for determination of degradability of drugs. The solutions were hold for a period of 28 days in a closed bottle at constant temperature in the dark or in diffuse light. Elimination of them was monitored by high performance liquid chromatography-diode array detector. The results showed that ampicillin, cephalexin and aceaminohen were completely eliminated but cefazolin and ceftazidime were eliminated 82% and 33% respectively within 28 days. In the second part of this thesis, solid-phase extraction (SPE) in combination with dispersive liquid-liquid microextraction (DLLME) has been developed as a sample pretreatment method with high enrichment factor for simultaneous extraction and sensitive determination of antidepressant drugs (desipramine, imipramine, amitriptyline and clomipramine) in water samples. In SPE-DLLME, antidepressant drugs were extracted from aqueous samples by a C 18 sorbent (200 mg). Then acetic acid (0.1 M)- methanol solution (15:85) was used for elution of target compounds from the sorbent and finally the DLLME technique was performed on the resulting solution. Extraction solvent (chloroform) was added to this solution and was shaked. Then, an aquous solution cantains 0.05 M NaOH was injected with a syringe (Gastight, Hamilton) rapidly in to the considerd solution. Finally, the mixture was centrifuged, and the sedimented phase was completely transferred to another test tube with conical bottom using a syringe. The organic solvent was evaporated by a calm flow of nitrogen gas and the residue was redissolved in 25 ?L mixture of acetonitrile-water (50:50), and 20 ?L of the solution was injected into reversed phase-high performance liquid chromatography-diode array detector (RP-HPLC-DAD). The effects of several important parameters influencing the extraction efficiency including flow rate of sample, sample volume, eluent volume, type and volume of the extraction solvent, type and volume of the Keywords: Closed Bottle Test, DLLME, SPE, HPLC-DAD, Pharmaceutical, Water samples.
