Extraction and determination of 2-pyrazoline derivatives using liquid phase microextraction based on solidification of floating organic drop

A simple, rapid and efficient microextraction method for the extraction and determination of some 2-pyrazoline derivative compounds in aqueous samples was developed. Microliter volumes of 1-undecanol were delivered to the surface of the aqueous sample and the sample was agitated for a desire time. The sample vial was cooled by inserting it into an ice bath for 5 min. The solidified solvent was transferred into a suitable vial and immediately melted. One μL of the organic solvent was injected into a gas chromatography (GC) for analysis. Several factors affecting the microextraction efficiency such as sampling temperature, stirring rate, pH, nature and volume of the organic solvent and extraction time were investigated and optimized values were obtained as 70 °C, 1250 rpm, 5.0, 8.0 μL (1-undecanol) and 30 min, respectively. Under the optimal conditions, detection limits of the method for determination of the compounds were in the range of 5–10 μg L−1. The relative standard deviations (RSDs%) for the extraction and determination of the analytes at the concentration level of 250 μg L−1 were in the range of 3.0–11.4. Dynamic linear ranges of 25–800 μg L−1 with correlation coefficients in the range of 0.9857 < r2 < 0.9968 were observed. After 30 min of extraction duration, the enrichment factors varied from 183 to 538. Finally, the study was applied to the determination of the compounds in several real samples including serum and urine and satisfactory results were obtained.