In this study, gas chromatography-mass spectrometry (GC-MS) following microwave distillation and solid-phase microextraction (MD-SPME) was developed for the analysis of essential oil compounds in Nepeta crispa. To improve the headspace (HS) method, microwave powers, irradiation times, and SPME fiber coatings were studied. The optimal experiment parameters obtained were 65-μm PDMS/DVB SPME fiber, a microwave power of 400 W, and an irradiation time of 3 min. MD-SPME was compared with headspace solid-phase microextraction (HS-SPME) and conventional hydrodistillation (HD) for the extraction of essential oil compounds in N. crispa. A comparative qualitative and quantitative study on the composition of the oils was carried out. For this, 26 compounds, constituting 98.2% of the oil, were identified in the essential oil by MD-SPME, and 23 compounds, representing 91.3% of the oil, were characterized in the SPME and HD methods; 25 compounds, constituting 94.6% of the oil, were separated and identified. The main compounds identified by all methods were 1,8-cineol, β-bourbonene, α-terpineol, and β-pinene. The relative standard deviation (RSD) values of less than 8% show that the MD-SPME method has good repeatability.It has been shown that the extraction of essential oils from N. crispa with MD-SPME was better in terms of energy saving, extraction time, plant material, oxygenated fractions, and product quality.

Molecularly imprinted polymer for the selective adsorption of oxazepam was synthesized using precipitation polymerization in the presence of oxazepam as a template, ethylene glycol dimethacrylate as a crosslinking agent, methacrylic acid as a functional monomer and 2,2-azobisisobutyronitrile as an initiator. The polymer was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy and thermogravimetric analysis. The obtained molecular imprinting polymer showed high affinity to template molecule and was used as a selective sorbent for selective extraction of oxazepam from human urine and plasma samples. Good linearity was obtained for the analyte in the range of 2.0-600 μg/L with relative standard deviation ≤ 4.0%. Under optimal conditions, maximum adsorption capacity obtained was 136 mg/g. The detection limit of the proposed procedure was 0.5 μg/L. Finally, this method was applied to the determination of oxazepam in plasma and urine samples and satisfactory results were achieved.

This paper describes a new approach for the determination of carbamazepine and lamotrigine in biological samples by ionic liquid dispersive liquid-phase microextraction prior to high-performance liquid chromatography with ultraviolet detection. The effects of different ionic liquids (ILs) on the extraction efficiency of carbamazepine and lamotrigine were investigated. The highest extraction efficiencies of carbamazepine and lamotrigine were obtained using 30 µL of 1-methyl-3-octylimidazolium hexafluorophosphate [C8MIM][PF6]. Several factors affecting the microextraction efficiency, such as the type and volume of extracting solvent, type and volume of disperser solvent, salt concentration, and pH of the sample solution have been optimized. The calibration plots were linear in the range of 0.1-20 mg L-1 for carbamazepine and 0.3-40 mg L-1 for lamotrigine with detection limits of 0.04 mg L-1 for carbamazepine and 0.07 mg L-1 for lamotrigine in plasma samples. The results confirm the suitability of the presented method as a sensitive method for the analysis of the target analytes in urine and plasma samples.

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A new and selective sorbent for molecularly imprinted polymer solid-phase extraction (MIP-SPE) was prepared to extract meropenem from plasma and urine samples. The extracted analyte was analyzed by high-performance liquid chromatography (HPLC) coupled with photodiode array detection. Methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, azobisisobutyronitrile (AIBN) as an initiator and meropenem as a template molecule were used for the MIP preparation. Imprinted meropenem molecule was removed from the polymeric structure using acetonitrile in water (1:9, v/v), as the eluent solvent. Under the optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 35 and 120 µg L-1 , respectively. The developed MIP-SPE method demonstrates that it could be applied for the determination of meropenem in plasma and urine samples. KEYWORDS Molecularly imprinted polymer, solid-phase extraction, meropenem, human urine and plasma, high-performance liquid chromatography.